// jpgd.cpp - C++ class for JPEG decompression. Written by Richard Geldreich <richgel99@gmail.com> between 1994-2020. // Supports progressive and baseline sequential JPEG image files, and the most common chroma subsampling factors: Y, H1V1, H2V1, H1V2, and H2V2. // Supports box and linear chroma upsampling. // // Released under two licenses. You are free to choose which license you want: // License 1: // Public Domain // // License 2: // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. // // Alex Evans: Linear memory allocator (taken from jpge.h). // v1.04, May. 19, 2012: Code tweaks to fix VS2008 static code analysis warnings // v2.00, March 20, 2020: Fuzzed with zzuf and afl. Fixed several issues, converted most assert()'s to run-time checks. Added chroma upsampling. Removed freq. domain upsampling. gcc/clang warnings. // // Important: // #define JPGD_USE_SSE2 to 0 to completely disable SSE2 usage. // #include "jpgd.h" #include <string.h> #include <algorithm> #include <assert.h> #ifdef _MSC_VER #pragma warning (disable : 4611) // warning C4611: interaction between '_setjmp' and C++ object destruction is non-portable #endif #ifndef JPGD_USE_SSE2 #if defined(__GNUC__) #if defined(__SSE2__) #define JPGD_USE_SSE2 (1) #endif #elif defined(_MSC_VER) #if defined(_M_X64) #define JPGD_USE_SSE2 (1) #endif #endif #endif #define JPGD_TRUE (1) #define JPGD_FALSE (0) #define JPGD_MAX(a,b) (((a)>(b)) ? (a) : (b)) #define JPGD_MIN(a,b) (((a)<(b)) ? (a) : (b)) namespace jpgd { static inline void* jpgd_malloc(size_t nSize) { return malloc(nSize); } static inline void jpgd_free(void* p) { free(p); } // DCT coefficients are stored in this sequence. static int g_ZAG[64] = { 0,1,8,16,9,2,3,10,17,24,32,25,18,11,4,5,12,19,26,33,40,48,41,34,27,20,13,6,7,14,21,28,35,42,49,56,57,50,43,36,29,22,15,23,30,37,44,51,58,59,52,45,38,31,39,46,53,60,61,54,47,55,62,63 }; enum JPEG_MARKER { M_SOF0 = 0xC0, M_SOF1 = 0xC1, M_SOF2 = 0xC2, M_SOF3 = 0xC3, M_SOF5 = 0xC5, M_SOF6 = 0xC6, M_SOF7 = 0xC7, M_JPG = 0xC8, M_SOF9 = 0xC9, M_SOF10 = 0xCA, M_SOF11 = 0xCB, M_SOF13 = 0xCD, M_SOF14 = 0xCE, M_SOF15 = 0xCF, M_DHT = 0xC4, M_DAC = 0xCC, M_RST0 = 0xD0, M_RST1 = 0xD1, M_RST2 = 0xD2, M_RST3 = 0xD3, M_RST4 = 0xD4, M_RST5 = 0xD5, M_RST6 = 0xD6, M_RST7 = 0xD7, M_SOI = 0xD8, M_EOI = 0xD9, M_SOS = 0xDA, M_DQT = 0xDB, M_DNL = 0xDC, M_DRI = 0xDD, M_DHP = 0xDE, M_EXP = 0xDF, M_APP0 = 0xE0, M_APP15 = 0xEF, M_JPG0 = 0xF0, M_JPG13 = 0xFD, M_COM = 0xFE, M_TEM = 0x01, M_ERROR = 0x100, RST0 = 0xD0 }; enum JPEG_SUBSAMPLING { JPGD_GRAYSCALE = 0, JPGD_YH1V1, JPGD_YH2V1, JPGD_YH1V2, JPGD_YH2V2 }; #if JPGD_USE_SSE2 #include "jpgd_idct.h" #endif #define CONST_BITS 13 #define PASS1_BITS 2 #define SCALEDONE ((int32)1) #define FIX_0_298631336 ((int32)2446) /* FIX(0.298631336) */ #define FIX_0_390180644 ((int32)3196) /* FIX(0.390180644) */ #define FIX_0_541196100 ((int32)4433) /* FIX(0.541196100) */ #define FIX_0_765366865 ((int32)6270) /* FIX(0.765366865) */ #define FIX_0_899976223 ((int32)7373) /* FIX(0.899976223) */ #define FIX_1_175875602 ((int32)9633) /* FIX(1.175875602) */ #define FIX_1_501321110 ((int32)12299) /* FIX(1.501321110) */ #define FIX_1_847759065 ((int32)15137) /* FIX(1.847759065) */ #define FIX_1_961570560 ((int32)16069) /* FIX(1.961570560) */ #define FIX_2_053119869 ((int32)16819) /* FIX(2.053119869) */ #define FIX_2_562915447 ((int32)20995) /* FIX(2.562915447) */ #define FIX_3_072711026 ((int32)25172) /* FIX(3.072711026) */ #define DESCALE(x,n) (((x) + (SCALEDONE << ((n)-1))) >> (n)) #define DESCALE_ZEROSHIFT(x,n) (((x) + (128 << (n)) + (SCALEDONE << ((n)-1))) >> (n)) #define MULTIPLY(var, cnst) ((var) * (cnst)) #define CLAMP(i) ((static_cast<uint>(i) > 255) ? (((~i) >> 31) & 0xFF) : (i)) static inline int left_shifti(int val, uint32_t bits) { return static_cast<int>(static_cast<uint32_t>(val) << bits); } // Compiler creates a fast path 1D IDCT for X non-zero columns template <int NONZERO_COLS> struct Row { static void idct(int* pTemp, const jpgd_block_coeff_t* pSrc) { // ACCESS_COL() will be optimized at compile time to either an array access, or 0. Good compilers will then optimize out muls against 0. #define ACCESS_COL(x) (((x) < NONZERO_COLS) ? (int)pSrc[x] : 0) const int z2 = ACCESS_COL(2), z3 = ACCESS_COL(6); const int z1 = MULTIPLY(z2 + z3, FIX_0_541196100); const int tmp2 = z1 + MULTIPLY(z3, -FIX_1_847759065); const int tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865); const int tmp0 = left_shifti(ACCESS_COL(0) + ACCESS_COL(4), CONST_BITS); const int tmp1 = left_shifti(ACCESS_COL(0) - ACCESS_COL(4), CONST_BITS); const int tmp10 = tmp0 + tmp3, tmp13 = tmp0 - tmp3, tmp11 = tmp1 + tmp2, tmp12 = tmp1 - tmp2; const int atmp0 = ACCESS_COL(7), atmp1 = ACCESS_COL(5), atmp2 = ACCESS_COL(3), atmp3 = ACCESS_COL(1); const int bz1 = atmp0 + atmp3, bz2 = atmp1 + atmp2, bz3 = atmp0 + atmp2, bz4 = atmp1 + atmp3; const int bz5 = MULTIPLY(bz3 + bz4, FIX_1_175875602); const int az1 = MULTIPLY(bz1, -FIX_0_899976223); const int az2 = MULTIPLY(bz2, -FIX_2_562915447); const int az3 = MULTIPLY(bz3, -FIX_1_961570560) + bz5; const int az4 = MULTIPLY(bz4, -FIX_0_390180644) + bz5; const int btmp0 = MULTIPLY(atmp0, FIX_0_298631336) + az1 + az3; const int btmp1 = MULTIPLY(atmp1, FIX_2_053119869) + az2 + az4; const int btmp2 = MULTIPLY(atmp2, FIX_3_072711026) + az2 + az3; const int btmp3 = MULTIPLY(atmp3, FIX_1_501321110) + az1 + az4; pTemp[0] = DESCALE(tmp10 + btmp3, CONST_BITS - PASS1_BITS); pTemp[7] = DESCALE(tmp10 - btmp3, CONST_BITS - PASS1_BITS); pTemp[1] = DESCALE(tmp11 + btmp2, CONST_BITS - PASS1_BITS); pTemp[6] = DESCALE(tmp11 - btmp2, CONST_BITS - PASS1_BITS); pTemp[2] = DESCALE(tmp12 + btmp1, CONST_BITS - PASS1_BITS); pTemp[5] = DESCALE(tmp12 - btmp1, CONST_BITS - PASS1_BITS); pTemp[3] = DESCALE(tmp13 + btmp0, CONST_BITS - PASS1_BITS); pTemp[4] = DESCALE(tmp13 - btmp0, CONST_BITS - PASS1_BITS); } }; template <> struct Row<0> { static void idct(int* pTemp, const jpgd_block_coeff_t* pSrc) { (void)pTemp; (void)pSrc; } }; template <> struct Row<1> { static void idct(int* pTemp, const jpgd_block_coeff_t* pSrc) { const int dcval = left_shifti(pSrc[0], PASS1_BITS); pTemp[0] = dcval; pTemp[1] = dcval; pTemp[2] = dcval; pTemp[3] = dcval; pTemp[4] = dcval; pTemp[5] = dcval; pTemp[6] = dcval; pTemp[7] = dcval; } }; // Compiler creates a fast path 1D IDCT for X non-zero rows template <int NONZERO_ROWS> struct Col { static void idct(uint8* pDst_ptr, const int* pTemp) { // ACCESS_ROW() will be optimized at compile time to either an array access, or 0. #define ACCESS_ROW(x) (((x) < NONZERO_ROWS) ? pTemp[x * 8] : 0) const int z2 = ACCESS_ROW(2); const int z3 = ACCESS_ROW(6); const int z1 = MULTIPLY(z2 + z3, FIX_0_541196100); const int tmp2 = z1 + MULTIPLY(z3, -FIX_1_847759065); const int tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865); const int tmp0 = left_shifti(ACCESS_ROW(0) + ACCESS_ROW(4), CONST_BITS); const int tmp1 = left_shifti(ACCESS_ROW(0) - ACCESS_ROW(4), CONST_BITS); const int tmp10 = tmp0 + tmp3, tmp13 = tmp0 - tmp3, tmp11 = tmp1 + tmp2, tmp12 = tmp1 - tmp2; const int atmp0 = ACCESS_ROW(7), atmp1 = ACCESS_ROW(5), atmp2 = ACCESS_ROW(3), atmp3 = ACCESS_ROW(1); const int bz1 = atmp0 + atmp3, bz2 = atmp1 + atmp2, bz3 = atmp0 + atmp2, bz4 = atmp1 + atmp3; const int bz5 = MULTIPLY(bz3 + bz4, FIX_1_175875602); const int az1 = MULTIPLY(bz1, -FIX_0_899976223); const int az2 = MULTIPLY(bz2, -FIX_2_562915447); const int az3 = MULTIPLY(bz3, -FIX_1_961570560) + bz5; const int az4 = MULTIPLY(bz4, -FIX_0_390180644) + bz5; const int btmp0 = MULTIPLY(atmp0, FIX_0_298631336) + az1 + az3; const int btmp1 = MULTIPLY(atmp1, FIX_2_053119869) + az2 + az4; const int btmp2 = MULTIPLY(atmp2, FIX_3_072711026) + az2 + az3; const int btmp3 = MULTIPLY(atmp3, FIX_1_501321110) + az1 + az4; int i = DESCALE_ZEROSHIFT(tmp10 + btmp3, CONST_BITS + PASS1_BITS + 3); pDst_ptr[8 * 0] = (uint8)CLAMP(i); i = DESCALE_ZEROSHIFT(tmp10 - btmp3, CONST_BITS + PASS1_BITS + 3); pDst_ptr[8 * 7] = (uint8)CLAMP(i); i = DESCALE_ZEROSHIFT(tmp11 + btmp2, CONST_BITS + PASS1_BITS + 3); pDst_ptr[8 * 1] = (uint8)CLAMP(i); i = DESCALE_ZEROSHIFT(tmp11 - btmp2, CONST_BITS + PASS1_BITS + 3); pDst_ptr[8 * 6] = (uint8)CLAMP(i); i = DESCALE_ZEROSHIFT(tmp12 + btmp1, CONST_BITS + PASS1_BITS + 3); pDst_ptr[8 * 2] = (uint8)CLAMP(i); i = DESCALE_ZEROSHIFT(tmp12 - btmp1, CONST_BITS + PASS1_BITS + 3); pDst_ptr[8 * 5] = (uint8)CLAMP(i); i = DESCALE_ZEROSHIFT(tmp13 + btmp0, CONST_BITS + PASS1_BITS + 3); pDst_ptr[8 * 3] = (uint8)CLAMP(i); i = DESCALE_ZEROSHIFT(tmp13 - btmp0, CONST_BITS + PASS1_BITS + 3); pDst_ptr[8 * 4] = (uint8)CLAMP(i); } }; template <> struct Col<1> { static void idct(uint8* pDst_ptr, const int* pTemp) { int dcval = DESCALE_ZEROSHIFT(pTemp[0], PASS1_BITS + 3); const uint8 dcval_clamped = (uint8)CLAMP(dcval); pDst_ptr[0 * 8] = dcval_clamped; pDst_ptr[1 * 8] = dcval_clamped; pDst_ptr[2 * 8] = dcval_clamped; pDst_ptr[3 * 8] = dcval_clamped; pDst_ptr[4 * 8] = dcval_clamped; pDst_ptr[5 * 8] = dcval_clamped; pDst_ptr[6 * 8] = dcval_clamped; pDst_ptr[7 * 8] = dcval_clamped; } }; static const uint8 s_idct_row_table[] = { 1,0,0,0,0,0,0,0, 2,0,0,0,0,0,0,0, 2,1,0,0,0,0,0,0, 2,1,1,0,0,0,0,0, 2,2,1,0,0,0,0,0, 3,2,1,0,0,0,0,0, 4,2,1,0,0,0,0,0, 4,3,1,0,0,0,0,0, 4,3,2,0,0,0,0,0, 4,3,2,1,0,0,0,0, 4,3,2,1,1,0,0,0, 4,3,2,2,1,0,0,0, 4,3,3,2,1,0,0,0, 4,4,3,2,1,0,0,0, 5,4,3,2,1,0,0,0, 6,4,3,2,1,0,0,0, 6,5,3,2,1,0,0,0, 6,5,4,2,1,0,0,0, 6,5,4,3,1,0,0,0, 6,5,4,3,2,0,0,0, 6,5,4,3,2,1,0,0, 6,5,4,3,2,1,1,0, 6,5,4,3,2,2,1,0, 6,5,4,3,3,2,1,0, 6,5,4,4,3,2,1,0, 6,5,5,4,3,2,1,0, 6,6,5,4,3,2,1,0, 7,6,5,4,3,2,1,0, 8,6,5,4,3,2,1,0, 8,7,5,4,3,2,1,0, 8,7,6,4,3,2,1,0, 8,7,6,5,3,2,1,0, 8,7,6,5,4,2,1,0, 8,7,6,5,4,3,1,0, 8,7,6,5,4,3,2,0, 8,7,6,5,4,3,2,1, 8,7,6,5,4,3,2,2, 8,7,6,5,4,3,3,2, 8,7,6,5,4,4,3,2, 8,7,6,5,5,4,3,2, 8,7,6,6,5,4,3,2, 8,7,7,6,5,4,3,2, 8,8,7,6,5,4,3,2, 8,8,8,6,5,4,3,2, 8,8,8,7,5,4,3,2, 8,8,8,7,6,4,3,2, 8,8,8,7,6,5,3,2, 8,8,8,7,6,5,4,2, 8,8,8,7,6,5,4,3, 8,8,8,7,6,5,4,4, 8,8,8,7,6,5,5,4, 8,8,8,7,6,6,5,4, 8,8,8,7,7,6,5,4, 8,8,8,8,7,6,5,4, 8,8,8,8,8,6,5,4, 8,8,8,8,8,7,5,4, 8,8,8,8,8,7,6,4, 8,8,8,8,8,7,6,5, 8,8,8,8,8,7,6,6, 8,8,8,8,8,7,7,6, 8,8,8,8,8,8,7,6, 8,8,8,8,8,8,8,6, 8,8,8,8,8,8,8,7, 8,8,8,8,8,8,8,8, }; static const uint8 s_idct_col_table[] = { 1, 1, 2, 3, 3, 3, 3, 3, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 }; // Scalar "fast pathing" IDCT. static void idct(const jpgd_block_coeff_t* pSrc_ptr, uint8* pDst_ptr, int block_max_zag, bool use_simd) { (void)use_simd; assert(block_max_zag >= 1); assert(block_max_zag <= 64); if (block_max_zag <= 1) { int k = ((pSrc_ptr[0] + 4) >> 3) + 128; k = CLAMP(k); k = k | (k << 8); k = k | (k << 16); for (int i = 8; i > 0; i--) { *(int*)&pDst_ptr[0] = k; *(int*)&pDst_ptr[4] = k; pDst_ptr += 8; } return; } #if JPGD_USE_SSE2 if (use_simd) { assert((((uintptr_t)pSrc_ptr) & 15) == 0); assert((((uintptr_t)pDst_ptr) & 15) == 0); idctSSEShortU8(pSrc_ptr, pDst_ptr); return; } #endif int temp[64]; const jpgd_block_coeff_t* pSrc = pSrc_ptr; int* pTemp = temp; const uint8* pRow_tab = &s_idct_row_table[(block_max_zag - 1) * 8]; int i; for (i = 8; i > 0; i--, pRow_tab++) { switch (*pRow_tab) { case 0: Row<0>::idct(pTemp, pSrc); break; case 1: Row<1>::idct(pTemp, pSrc); break; case 2: Row<2>::idct(pTemp, pSrc); break; case 3: Row<3>::idct(pTemp, pSrc); break; case 4: Row<4>::idct(pTemp, pSrc); break; case 5: Row<5>::idct(pTemp, pSrc); break; case 6: Row<6>::idct(pTemp, pSrc); break; case 7: Row<7>::idct(pTemp, pSrc); break; case 8: Row<8>::idct(pTemp, pSrc); break; } pSrc += 8; pTemp += 8; } pTemp = temp; const int nonzero_rows = s_idct_col_table[block_max_zag - 1]; for (i = 8; i > 0; i--) { switch (nonzero_rows) { case 1: Col<1>::idct(pDst_ptr, pTemp); break; case 2: Col<2>::idct(pDst_ptr, pTemp); break; case 3: Col<3>::idct(pDst_ptr, pTemp); break; case 4: Col<4>::idct(pDst_ptr, pTemp); break; case 5: Col<5>::idct(pDst_ptr, pTemp); break; case 6: Col<6>::idct(pDst_ptr, pTemp); break; case 7: Col<7>::idct(pDst_ptr, pTemp); break; case 8: Col<8>::idct(pDst_ptr, pTemp); break; } pTemp++; pDst_ptr++; } } // Retrieve one character from the input stream. inline uint jpeg_decoder::get_char() { // Any bytes remaining in buffer? if (!m_in_buf_left) { // Try to get more bytes. prep_in_buffer(); // Still nothing to get? if (!m_in_buf_left) { // Pad the end of the stream with 0xFF 0xD9 (EOI marker) int t = m_tem_flag; m_tem_flag ^= 1; if (t) return 0xD9; else return 0xFF; } } uint c = *m_pIn_buf_ofs++; m_in_buf_left--; return c; } // Same as previous method, except can indicate if the character is a pad character or not. inline uint jpeg_decoder::get_char(bool* pPadding_flag) { if (!m_in_buf_left) { prep_in_buffer(); if (!m_in_buf_left) { *pPadding_flag = true; int t = m_tem_flag; m_tem_flag ^= 1; if (t) return 0xD9; else return 0xFF; } } *pPadding_flag = false; uint c = *m_pIn_buf_ofs++; m_in_buf_left--; return c; } // Inserts a previously retrieved character back into the input buffer. inline void jpeg_decoder::stuff_char(uint8 q) { // This could write before the input buffer, but we've placed another array there. *(--m_pIn_buf_ofs) = q; m_in_buf_left++; } // Retrieves one character from the input stream, but does not read past markers. Will continue to return 0xFF when a marker is encountered. inline uint8 jpeg_decoder::get_octet() { bool padding_flag; int c = get_char(&padding_flag); if (c == 0xFF) { if (padding_flag) return 0xFF; c = get_char(&padding_flag); if (padding_flag) { stuff_char(0xFF); return 0xFF; } if (c == 0x00) return 0xFF; else { stuff_char(static_cast<uint8>(c)); stuff_char(0xFF); return 0xFF; } } return static_cast<uint8>(c); } // Retrieves a variable number of bits from the input stream. Does not recognize markers. inline uint jpeg_decoder::get_bits(int num_bits) { if (!num_bits) return 0; uint i = m_bit_buf >> (32 - num_bits); if ((m_bits_left -= num_bits) <= 0) { m_bit_buf <<= (num_bits += m_bits_left); uint c1 = get_char(); uint c2 = get_char(); m_bit_buf = (m_bit_buf & 0xFFFF0000) | (c1 << 8) | c2; m_bit_buf <<= -m_bits_left; m_bits_left += 16; assert(m_bits_left >= 0); } else m_bit_buf <<= num_bits; return i; } // Retrieves a variable number of bits from the input stream. Markers will not be read into the input bit buffer. Instead, an infinite number of all 1's will be returned when a marker is encountered. inline uint jpeg_decoder::get_bits_no_markers(int num_bits) { if (!num_bits) return 0; assert(num_bits <= 16); uint i = m_bit_buf >> (32 - num_bits); if ((m_bits_left -= num_bits) <= 0) { m_bit_buf <<= (num_bits += m_bits_left); if ((m_in_buf_left < 2) || (m_pIn_buf_ofs[0] == 0xFF) || (m_pIn_buf_ofs[1] == 0xFF)) { uint c1 = get_octet(); uint c2 = get_octet(); m_bit_buf |= (c1 << 8) | c2; } else { m_bit_buf |= ((uint)m_pIn_buf_ofs[0] << 8) | m_pIn_buf_ofs[1]; m_in_buf_left -= 2; m_pIn_buf_ofs += 2; } m_bit_buf <<= -m_bits_left; m_bits_left += 16; assert(m_bits_left >= 0); } else m_bit_buf <<= num_bits; return i; } // Decodes a Huffman encoded symbol. inline int jpeg_decoder::huff_decode(huff_tables* pH) { if (!pH) stop_decoding(JPGD_DECODE_ERROR); int symbol; // Check first 8-bits: do we have a complete symbol? if ((symbol = pH->look_up[m_bit_buf >> 24]) < 0) { // Decode more bits, use a tree traversal to find symbol. int ofs = 23; do { unsigned int idx = -(int)(symbol + ((m_bit_buf >> ofs) & 1)); // This should never happen, but to be safe I'm turning these asserts into a run-time check. if ((idx >= JPGD_HUFF_TREE_MAX_LENGTH) || (ofs < 0)) stop_decoding(JPGD_DECODE_ERROR); symbol = pH->tree[idx]; ofs--; } while (symbol < 0); get_bits_no_markers(8 + (23 - ofs)); } else { assert(symbol < JPGD_HUFF_CODE_SIZE_MAX_LENGTH); get_bits_no_markers(pH->code_size[symbol]); } return symbol; } // Decodes a Huffman encoded symbol. inline int jpeg_decoder::huff_decode(huff_tables* pH, int& extra_bits) { int symbol; if (!pH) stop_decoding(JPGD_DECODE_ERROR); // Check first 8-bits: do we have a complete symbol? if ((symbol = pH->look_up2[m_bit_buf >> 24]) < 0) { // Use a tree traversal to find symbol. int ofs = 23; do { unsigned int idx = -(int)(symbol + ((m_bit_buf >> ofs) & 1)); // This should never happen, but to be safe I'm turning these asserts into a run-time check. if ((idx >= JPGD_HUFF_TREE_MAX_LENGTH) || (ofs < 0)) stop_decoding(JPGD_DECODE_ERROR); symbol = pH->tree[idx]; ofs--; } while (symbol < 0); get_bits_no_markers(8 + (23 - ofs)); extra_bits = get_bits_no_markers(symbol & 0xF); } else { if (symbol & 0x8000) { //get_bits_no_markers((symbol >> 8) & 31); assert(((symbol >> 8) & 31) <= 15); get_bits_no_markers((symbol >> 8) & 15); extra_bits = symbol >> 16; } else { int code_size = (symbol >> 8) & 31; int num_extra_bits = symbol & 0xF; int bits = code_size + num_extra_bits; if (bits <= 16) extra_bits = get_bits_no_markers(bits) & ((1 << num_extra_bits) - 1); else { get_bits_no_markers(code_size); extra_bits = get_bits_no_markers(num_extra_bits); } } symbol &= 0xFF; } return symbol; } // Tables and macro used to fully decode the DPCM differences. static const int s_extend_test[16] = { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 }; static const int s_extend_offset[16] = { 0, -1, -3, -7, -15, -31, -63, -127, -255, -511, -1023, -2047, -4095, -8191, -16383, -32767 }; //static const int s_extend_mask[] = { 0, (1 << 0), (1 << 1), (1 << 2), (1 << 3), (1 << 4), (1 << 5), (1 << 6), (1 << 7), (1 << 8), (1 << 9), (1 << 10), (1 << 11), (1 << 12), (1 << 13), (1 << 14), (1 << 15), (1 << 16) }; #define JPGD_HUFF_EXTEND(x, s) (((x) < s_extend_test[s & 15]) ? ((x) + s_extend_offset[s & 15]) : (x)) // Unconditionally frees all allocated m_blocks. void jpeg_decoder::free_all_blocks() { m_pStream = nullptr; for (mem_block* b = m_pMem_blocks; b; ) { mem_block* n = b->m_pNext; jpgd_free(b); b = n; } m_pMem_blocks = nullptr; } // This method handles all errors. It will never return. // It could easily be changed to use C++ exceptions. JPGD_NORETURN void jpeg_decoder::stop_decoding(jpgd_status status) { m_error_code = status; free_all_blocks(); longjmp(m_jmp_state, status); } void* jpeg_decoder::alloc(size_t nSize, bool zero) { nSize = (JPGD_MAX(nSize, 1) + 3) & ~3; char* rv = nullptr; for (mem_block* b = m_pMem_blocks; b; b = b->m_pNext) { if ((b->m_used_count + nSize) <= b->m_size) { rv = b->m_data + b->m_used_count; b->m_used_count += nSize; break; } } if (!rv) { int capacity = JPGD_MAX(32768 - 256, (nSize + 2047) & ~2047); mem_block* b = (mem_block*)jpgd_malloc(sizeof(mem_block) + capacity); if (!b) { stop_decoding(JPGD_NOTENOUGHMEM); } b->m_pNext = m_pMem_blocks; m_pMem_blocks = b; b->m_used_count = nSize; b->m_size = capacity; rv = b->m_data; } if (zero) memset(rv, 0, nSize); return rv; } void* jpeg_decoder::alloc_aligned(size_t nSize, uint32_t align, bool zero) { assert((align >= 1U) && ((align & (align - 1U)) == 0U)); void *p = alloc(nSize + align - 1U, zero); p = (void *)( ((uintptr_t)p + (align - 1U)) & ~((uintptr_t)(align - 1U)) ); return p; } void jpeg_decoder::word_clear(void* p, uint16 c, uint n) { uint8* pD = (uint8*)p; const uint8 l = c & 0xFF, h = (c >> 8) & 0xFF; while (n) { pD[0] = l; pD[1] = h; pD += 2; n--; } } // Refill the input buffer. // This method will sit in a loop until (A) the buffer is full or (B) // the stream's read() method reports and end of file condition. void jpeg_decoder::prep_in_buffer() { m_in_buf_left = 0; m_pIn_buf_ofs = m_in_buf; if (m_eof_flag) return; do { int bytes_read = m_pStream->read(m_in_buf + m_in_buf_left, JPGD_IN_BUF_SIZE - m_in_buf_left, &m_eof_flag); if (bytes_read == -1) stop_decoding(JPGD_STREAM_READ); m_in_buf_left += bytes_read; } while ((m_in_buf_left < JPGD_IN_BUF_SIZE) && (!m_eof_flag)); m_total_bytes_read += m_in_buf_left; // Pad the end of the block with M_EOI (prevents the decompressor from going off the rails if the stream is invalid). // (This dates way back to when this decompressor was written in C/asm, and the all-asm Huffman decoder did some fancy things to increase perf.) word_clear(m_pIn_buf_ofs + m_in_buf_left, 0xD9FF, 64); } // Read a Huffman code table. void jpeg_decoder::read_dht_marker() { int i, index, count; uint8 huff_num[17]; uint8 huff_val[256]; uint num_left = get_bits(16); if (num_left < 2) stop_decoding(JPGD_BAD_DHT_MARKER); num_left -= 2; while (num_left) { index = get_bits(8); huff_num[0] = 0; count = 0; for (i = 1; i <= 16; i++) { huff_num[i] = static_cast<uint8>(get_bits(8)); count += huff_num[i]; } if (count > 255) stop_decoding(JPGD_BAD_DHT_COUNTS); bool symbol_present[256]; memset(symbol_present, 0, sizeof(symbol_present)); for (i = 0; i < count; i++) { const int s = get_bits(8); // Check for obviously bogus tables. if (symbol_present[s]) stop_decoding(JPGD_BAD_DHT_COUNTS); huff_val[i] = static_cast<uint8_t>(s); symbol_present[s] = true; } i = 1 + 16 + count; if (num_left < (uint)i) stop_decoding(JPGD_BAD_DHT_MARKER); num_left -= i; if ((index & 0x10) > 0x10) stop_decoding(JPGD_BAD_DHT_INDEX); index = (index & 0x0F) + ((index & 0x10) >> 4) * (JPGD_MAX_HUFF_TABLES >> 1); if (index >= JPGD_MAX_HUFF_TABLES) stop_decoding(JPGD_BAD_DHT_INDEX); if (!m_huff_num[index]) m_huff_num[index] = (uint8*)alloc(17); if (!m_huff_val[index]) m_huff_val[index] = (uint8*)alloc(256); m_huff_ac[index] = (index & 0x10) != 0; memcpy(m_huff_num[index], huff_num, 17); memcpy(m_huff_val[index], huff_val, 256); } } // Read a quantization table. void jpeg_decoder::read_dqt_marker() { int n, i, prec; uint num_left; uint temp; num_left = get_bits(16); if (num_left < 2) stop_decoding(JPGD_BAD_DQT_MARKER); num_left -= 2; while (num_left) { n = get_bits(8); prec = n >> 4; n &= 0x0F; if (n >= JPGD_MAX_QUANT_TABLES) stop_decoding(JPGD_BAD_DQT_TABLE); if (!m_quant[n]) m_quant[n] = (jpgd_quant_t*)alloc(64 * sizeof(jpgd_quant_t)); // read quantization entries, in zag order for (i = 0; i < 64; i++) { temp = get_bits(8); if (prec) temp = (temp << 8) + get_bits(8); m_quant[n][i] = static_cast<jpgd_quant_t>(temp); } i = 64 + 1; if (prec) i += 64; if (num_left < (uint)i) stop_decoding(JPGD_BAD_DQT_LENGTH); num_left -= i; } } // Read the start of frame (SOF) marker. void jpeg_decoder::read_sof_marker() { int i; uint num_left; num_left = get_bits(16); /* precision: sorry, only 8-bit precision is supported */ if (get_bits(8) != 8) stop_decoding(JPGD_BAD_PRECISION); m_image_y_size = get_bits(16); if ((m_image_y_size < 1) || (m_image_y_size > JPGD_MAX_HEIGHT)) stop_decoding(JPGD_BAD_HEIGHT); m_image_x_size = get_bits(16); if ((m_image_x_size < 1) || (m_image_x_size > JPGD_MAX_WIDTH)) stop_decoding(JPGD_BAD_WIDTH); m_comps_in_frame = get_bits(8); if (m_comps_in_frame > JPGD_MAX_COMPONENTS) stop_decoding(JPGD_TOO_MANY_COMPONENTS); if (num_left != (uint)(m_comps_in_frame * 3 + 8)) stop_decoding(JPGD_BAD_SOF_LENGTH); for (i = 0; i < m_comps_in_frame; i++) { m_comp_ident[i] = get_bits(8); m_comp_h_samp[i] = get_bits(4); m_comp_v_samp[i] = get_bits(4); if (!m_comp_h_samp[i] || !m_comp_v_samp[i] || (m_comp_h_samp[i] > 2) || (m_comp_v_samp[i] > 2)) stop_decoding(JPGD_UNSUPPORTED_SAMP_FACTORS); m_comp_quant[i] = get_bits(8); if (m_comp_quant[i] >= JPGD_MAX_QUANT_TABLES) stop_decoding(JPGD_DECODE_ERROR); } } // Used to skip unrecognized markers. void jpeg_decoder::skip_variable_marker() { uint num_left; num_left = get_bits(16); if (num_left < 2) stop_decoding(JPGD_BAD_VARIABLE_MARKER); num_left -= 2; while (num_left) { get_bits(8); num_left--; } } // Read a define restart interval (DRI) marker. void jpeg_decoder::read_dri_marker() { if (get_bits(16) != 4) stop_decoding(JPGD_BAD_DRI_LENGTH); m_restart_interval = get_bits(16); } // Read a start of scan (SOS) marker. void jpeg_decoder::read_sos_marker() { uint num_left; int i, ci, n, c, cc; num_left = get_bits(16); n = get_bits(8); m_comps_in_scan = n; num_left -= 3; if ((num_left != (uint)(n * 2 + 3)) || (n < 1) || (n > JPGD_MAX_COMPS_IN_SCAN)) stop_decoding(JPGD_BAD_SOS_LENGTH); for (i = 0; i < n; i++) { cc = get_bits(8); c = get_bits(8); num_left -= 2; for (ci = 0; ci < m_comps_in_frame; ci++) if (cc == m_comp_ident[ci]) break; if (ci >= m_comps_in_frame) stop_decoding(JPGD_BAD_SOS_COMP_ID); if (ci >= JPGD_MAX_COMPONENTS) stop_decoding(JPGD_DECODE_ERROR); m_comp_list[i] = ci; m_comp_dc_tab[ci] = (c >> 4) & 15; m_comp_ac_tab[ci] = (c & 15) + (JPGD_MAX_HUFF_TABLES >> 1); if (m_comp_dc_tab[ci] >= JPGD_MAX_HUFF_TABLES) stop_decoding(JPGD_DECODE_ERROR); if (m_comp_ac_tab[ci] >= JPGD_MAX_HUFF_TABLES) stop_decoding(JPGD_DECODE_ERROR); } m_spectral_start = get_bits(8); m_spectral_end = get_bits(8); m_successive_high = get_bits(4); m_successive_low = get_bits(4); if (!m_progressive_flag) { m_spectral_start = 0; m_spectral_end = 63; } num_left -= 3; /* read past whatever is num_left */ while (num_left) { get_bits(8); num_left--; } } // Finds the next marker. int jpeg_decoder::next_marker() { uint c, bytes; bytes = 0; do { do { bytes++; c = get_bits(8); } while (c != 0xFF); do { c = get_bits(8); } while (c == 0xFF); } while (c == 0); // If bytes > 0 here, there where extra bytes before the marker (not good). return c; } // Process markers. Returns when an SOFx, SOI, EOI, or SOS marker is // encountered. int jpeg_decoder::process_markers() { int c; for (; ; ) { c = next_marker(); switch (c) { case M_SOF0: case M_SOF1: case M_SOF2: case M_SOF3: case M_SOF5: case M_SOF6: case M_SOF7: // case M_JPG: case M_SOF9: case M_SOF10: case M_SOF11: case M_SOF13: case M_SOF14: case M_SOF15: case M_SOI: case M_EOI: case M_SOS: { return c; } case M_DHT: { read_dht_marker(); break; } // No arithmitic support - dumb patents! case M_DAC: { stop_decoding(JPGD_NO_ARITHMITIC_SUPPORT); break; } case M_DQT: { read_dqt_marker(); break; } case M_DRI: { read_dri_marker(); break; } //case M_APP0: /* no need to read the JFIF marker */ case M_JPG: case M_RST0: /* no parameters */ case M_RST1: case M_RST2: case M_RST3: case M_RST4: case M_RST5: case M_RST6: case M_RST7: case M_TEM: { stop_decoding(JPGD_UNEXPECTED_MARKER); break; } default: /* must be DNL, DHP, EXP, APPn, JPGn, COM, or RESn or APP0 */ { skip_variable_marker(); break; } } } } // Finds the start of image (SOI) marker. void jpeg_decoder::locate_soi_marker() { uint lastchar, thischar; uint bytesleft; lastchar = get_bits(8); thischar = get_bits(8); /* ok if it's a normal JPEG file without a special header */ if ((lastchar == 0xFF) && (thischar == M_SOI)) return; bytesleft = 4096; for (; ; ) { if (--bytesleft == 0) stop_decoding(JPGD_NOT_JPEG); lastchar = thischar; thischar = get_bits(8); if (lastchar == 0xFF) { if (thischar == M_SOI) break; else if (thischar == M_EOI) // get_bits will keep returning M_EOI if we read past the end stop_decoding(JPGD_NOT_JPEG); } } // Check the next character after marker: if it's not 0xFF, it can't be the start of the next marker, so the file is bad. thischar = (m_bit_buf >> 24) & 0xFF; if (thischar != 0xFF) stop_decoding(JPGD_NOT_JPEG); } // Find a start of frame (SOF) marker. void jpeg_decoder::locate_sof_marker() { locate_soi_marker(); int c = process_markers(); switch (c) { case M_SOF2: { m_progressive_flag = JPGD_TRUE; read_sof_marker(); break; } case M_SOF0: /* baseline DCT */ case M_SOF1: /* extended sequential DCT */ { read_sof_marker(); break; } case M_SOF9: /* Arithmitic coding */ { stop_decoding(JPGD_NO_ARITHMITIC_SUPPORT); break; } default: { stop_decoding(JPGD_UNSUPPORTED_MARKER); break; } } } // Find a start of scan (SOS) marker. int jpeg_decoder::locate_sos_marker() { int c; c = process_markers(); if (c == M_EOI) return JPGD_FALSE; else if (c != M_SOS) stop_decoding(JPGD_UNEXPECTED_MARKER); read_sos_marker(); return JPGD_TRUE; } // Reset everything to default/uninitialized state. void jpeg_decoder::init(jpeg_decoder_stream* pStream, uint32_t flags) { m_flags = flags; m_pMem_blocks = nullptr; m_error_code = JPGD_SUCCESS; m_ready_flag = false; m_image_x_size = m_image_y_size = 0; m_pStream = pStream; m_progressive_flag = JPGD_FALSE; memset(m_huff_ac, 0, sizeof(m_huff_ac)); memset(m_huff_num, 0, sizeof(m_huff_num)); memset(m_huff_val, 0, sizeof(m_huff_val)); memset(m_quant, 0, sizeof(m_quant)); m_scan_type = 0; m_comps_in_frame = 0; memset(m_comp_h_samp, 0, sizeof(m_comp_h_samp)); memset(m_comp_v_samp, 0, sizeof(m_comp_v_samp)); memset(m_comp_quant, 0, sizeof(m_comp_quant)); memset(m_comp_ident, 0, sizeof(m_comp_ident)); memset(m_comp_h_blocks, 0, sizeof(m_comp_h_blocks)); memset(m_comp_v_blocks, 0, sizeof(m_comp_v_blocks)); m_comps_in_scan = 0; memset(m_comp_list, 0, sizeof(m_comp_list)); memset(m_comp_dc_tab, 0, sizeof(m_comp_dc_tab)); memset(m_comp_ac_tab, 0, sizeof(m_comp_ac_tab)); m_spectral_start = 0; m_spectral_end = 0; m_successive_low = 0; m_successive_high = 0; m_max_mcu_x_size = 0; m_max_mcu_y_size = 0; m_blocks_per_mcu = 0; m_max_blocks_per_row = 0; m_mcus_per_row = 0; m_mcus_per_col = 0; memset(m_mcu_org, 0, sizeof(m_mcu_org)); m_total_lines_left = 0; m_mcu_lines_left = 0; m_num_buffered_scanlines = 0; m_real_dest_bytes_per_scan_line = 0; m_dest_bytes_per_scan_line = 0; m_dest_bytes_per_pixel = 0; memset(m_pHuff_tabs, 0, sizeof(m_pHuff_tabs)); memset(m_dc_coeffs, 0, sizeof(m_dc_coeffs)); memset(m_ac_coeffs, 0, sizeof(m_ac_coeffs)); memset(m_block_y_mcu, 0, sizeof(m_block_y_mcu)); m_eob_run = 0; m_pIn_buf_ofs = m_in_buf; m_in_buf_left = 0; m_eof_flag = false; m_tem_flag = 0; memset(m_in_buf_pad_start, 0, sizeof(m_in_buf_pad_start)); memset(m_in_buf, 0, sizeof(m_in_buf)); memset(m_in_buf_pad_end, 0, sizeof(m_in_buf_pad_end)); m_restart_interval = 0; m_restarts_left = 0; m_next_restart_num = 0; m_max_mcus_per_row = 0; m_max_blocks_per_mcu = 0; m_max_mcus_per_col = 0; memset(m_last_dc_val, 0, sizeof(m_last_dc_val)); m_pMCU_coefficients = nullptr; m_pSample_buf = nullptr; m_pSample_buf_prev = nullptr; m_sample_buf_prev_valid = false; m_total_bytes_read = 0; m_pScan_line_0 = nullptr; m_pScan_line_1 = nullptr; // Ready the input buffer. prep_in_buffer(); // Prime the bit buffer. m_bits_left = 16; m_bit_buf = 0; get_bits(16); get_bits(16); for (int i = 0; i < JPGD_MAX_BLOCKS_PER_MCU; i++) m_mcu_block_max_zag[i] = 64; m_has_sse2 = false; #if JPGD_USE_SSE2 #ifdef _MSC_VER int cpu_info[4]; __cpuid(cpu_info, 1); const int cpu_info3 = cpu_info[3]; m_has_sse2 = ((cpu_info3 >> 26U) & 1U) != 0U; #else m_has_sse2 = true; #endif #endif } #define SCALEBITS 16 #define ONE_HALF ((int) 1 << (SCALEBITS-1)) #define FIX(x) ((int) ((x) * (1L<<SCALEBITS) + 0.5f)) // Create a few tables that allow us to quickly convert YCbCr to RGB. void jpeg_decoder::create_look_ups() { for (int i = 0; i <= 255; i++) { int k = i - 128; m_crr[i] = (FIX(1.40200f) * k + ONE_HALF) >> SCALEBITS; m_cbb[i] = (FIX(1.77200f) * k + ONE_HALF) >> SCALEBITS; m_crg[i] = (-FIX(0.71414f)) * k; m_cbg[i] = (-FIX(0.34414f)) * k + ONE_HALF; } } // This method throws back into the stream any bytes that where read // into the bit buffer during initial marker scanning. void jpeg_decoder::fix_in_buffer() { // In case any 0xFF's where pulled into the buffer during marker scanning. assert((m_bits_left & 7) == 0); if (m_bits_left == 16) stuff_char((uint8)(m_bit_buf & 0xFF)); if (m_bits_left >= 8) stuff_char((uint8)((m_bit_buf >> 8) & 0xFF)); stuff_char((uint8)((m_bit_buf >> 16) & 0xFF)); stuff_char((uint8)((m_bit_buf >> 24) & 0xFF)); m_bits_left = 16; get_bits_no_markers(16); get_bits_no_markers(16); } void jpeg_decoder::transform_mcu(int mcu_row) { jpgd_block_coeff_t* pSrc_ptr = m_pMCU_coefficients; if (mcu_row * m_blocks_per_mcu >= m_max_blocks_per_row) stop_decoding(JPGD_DECODE_ERROR); uint8* pDst_ptr = m_pSample_buf + mcu_row * m_blocks_per_mcu * 64; for (int mcu_block = 0; mcu_block < m_blocks_per_mcu; mcu_block++) { idct(pSrc_ptr, pDst_ptr, m_mcu_block_max_zag[mcu_block], ((m_flags & cFlagDisableSIMD) == 0) && m_has_sse2); pSrc_ptr += 64; pDst_ptr += 64; } } // Loads and dequantizes the next row of (already decoded) coefficients. // Progressive images only. void jpeg_decoder::load_next_row() { int i; jpgd_block_coeff_t* p; jpgd_quant_t* q; int mcu_row, mcu_block, row_block = 0; int component_num, component_id; int block_x_mcu[JPGD_MAX_COMPONENTS]; memset(block_x_mcu, 0, JPGD_MAX_COMPONENTS * sizeof(int)); for (mcu_row = 0; mcu_row < m_mcus_per_row; mcu_row++) { int block_x_mcu_ofs = 0, block_y_mcu_ofs = 0; for (mcu_block = 0; mcu_block < m_blocks_per_mcu; mcu_block++) { component_id = m_mcu_org[mcu_block]; if (m_comp_quant[component_id] >= JPGD_MAX_QUANT_TABLES) stop_decoding(JPGD_DECODE_ERROR); q = m_quant[m_comp_quant[component_id]]; p = m_pMCU_coefficients + 64 * mcu_block; jpgd_block_coeff_t* pAC = coeff_buf_getp(m_ac_coeffs[component_id], block_x_mcu[component_id] + block_x_mcu_ofs, m_block_y_mcu[component_id] + block_y_mcu_ofs); jpgd_block_coeff_t* pDC = coeff_buf_getp(m_dc_coeffs[component_id], block_x_mcu[component_id] + block_x_mcu_ofs, m_block_y_mcu[component_id] + block_y_mcu_ofs); p[0] = pDC[0]; memcpy(&p[1], &pAC[1], 63 * sizeof(jpgd_block_coeff_t)); for (i = 63; i > 0; i--) if (p[g_ZAG[i]]) break; m_mcu_block_max_zag[mcu_block] = i + 1; for (; i >= 0; i--) if (p[g_ZAG[i]]) p[g_ZAG[i]] = static_cast<jpgd_block_coeff_t>(p[g_ZAG[i]] * q[i]); row_block++; if (m_comps_in_scan == 1) block_x_mcu[component_id]++; else { if (++block_x_mcu_ofs == m_comp_h_samp[component_id]) { block_x_mcu_ofs = 0; if (++block_y_mcu_ofs == m_comp_v_samp[component_id]) { block_y_mcu_ofs = 0; block_x_mcu[component_id] += m_comp_h_samp[component_id]; } } } } transform_mcu(mcu_row); } if (m_comps_in_scan == 1) m_block_y_mcu[m_comp_list[0]]++; else { for (component_num = 0; component_num < m_comps_in_scan; component_num++) { component_id = m_comp_list[component_num]; m_block_y_mcu[component_id] += m_comp_v_samp[component_id]; } } } // Restart interval processing. void jpeg_decoder::process_restart() { int i; int c = 0; // Align to a byte boundry // FIXME: Is this really necessary? get_bits_no_markers() never reads in markers! //get_bits_no_markers(m_bits_left & 7); // Let's scan a little bit to find the marker, but not _too_ far. // 1536 is a "fudge factor" that determines how much to scan. for (i = 1536; i > 0; i--) if (get_char() == 0xFF) break; if (i == 0) stop_decoding(JPGD_BAD_RESTART_MARKER); for (; i > 0; i--) if ((c = get_char()) != 0xFF) break; if (i == 0) stop_decoding(JPGD_BAD_RESTART_MARKER); // Is it the expected marker? If not, something bad happened. if (c != (m_next_restart_num + M_RST0)) stop_decoding(JPGD_BAD_RESTART_MARKER); // Reset each component's DC prediction values. memset(&m_last_dc_val, 0, m_comps_in_frame * sizeof(uint)); m_eob_run = 0; m_restarts_left = m_restart_interval; m_next_restart_num = (m_next_restart_num + 1) & 7; // Get the bit buffer going again... m_bits_left = 16; get_bits_no_markers(16); get_bits_no_markers(16); } static inline int dequantize_ac(int c, int q) { c *= q; return c; } // Decodes and dequantizes the next row of coefficients. void jpeg_decoder::decode_next_row() { int row_block = 0; for (int mcu_row = 0; mcu_row < m_mcus_per_row; mcu_row++) { if ((m_restart_interval) && (m_restarts_left == 0)) process_restart(); jpgd_block_coeff_t* p = m_pMCU_coefficients; for (int mcu_block = 0; mcu_block < m_blocks_per_mcu; mcu_block++, p += 64) { int component_id = m_mcu_org[mcu_block]; if (m_comp_quant[component_id] >= JPGD_MAX_QUANT_TABLES) stop_decoding(JPGD_DECODE_ERROR); jpgd_quant_t* q = m_quant[m_comp_quant[component_id]]; int r, s; s = huff_decode(m_pHuff_tabs[m_comp_dc_tab[component_id]], r); if (s >= 16) stop_decoding(JPGD_DECODE_ERROR); s = JPGD_HUFF_EXTEND(r, s); m_last_dc_val[component_id] = (s += m_last_dc_val[component_id]); p[0] = static_cast<jpgd_block_coeff_t>(s * q[0]); int prev_num_set = m_mcu_block_max_zag[mcu_block]; huff_tables* pH = m_pHuff_tabs[m_comp_ac_tab[component_id]]; int k; for (k = 1; k < 64; k++) { int extra_bits; s = huff_decode(pH, extra_bits); r = s >> 4; s &= 15; if (s) { if (r) { if ((k + r) > 63) stop_decoding(JPGD_DECODE_ERROR); if (k < prev_num_set) { int n = JPGD_MIN(r, prev_num_set - k); int kt = k; while (n--) p[g_ZAG[kt++]] = 0; } k += r; } s = JPGD_HUFF_EXTEND(extra_bits, s); if (k >= 64) stop_decoding(JPGD_DECODE_ERROR); p[g_ZAG[k]] = static_cast<jpgd_block_coeff_t>(dequantize_ac(s, q[k])); //s * q[k]; } else { if (r == 15) { if ((k + 16) > 64) stop_decoding(JPGD_DECODE_ERROR); if (k < prev_num_set) { int n = JPGD_MIN(16, prev_num_set - k); int kt = k; while (n--) { if (kt > 63) stop_decoding(JPGD_DECODE_ERROR); p[g_ZAG[kt++]] = 0; } } k += 16 - 1; // - 1 because the loop counter is k if (p[g_ZAG[k & 63]] != 0) stop_decoding(JPGD_DECODE_ERROR); } else break; } } if (k < prev_num_set) { int kt = k; while (kt < prev_num_set) p[g_ZAG[kt++]] = 0; } m_mcu_block_max_zag[mcu_block] = k; row_block++; } transform_mcu(mcu_row); m_restarts_left--; } } // YCbCr H1V1 (1x1:1:1, 3 m_blocks per MCU) to RGB void jpeg_decoder::H1V1Convert() { int row = m_max_mcu_y_size - m_mcu_lines_left; uint8* d = m_pScan_line_0; uint8* s = m_pSample_buf + row * 8; for (int i = m_max_mcus_per_row; i > 0; i--) { for (int j = 0; j < 8; j++) { int y = s[j]; int cb = s[64 + j]; int cr = s[128 + j]; d[0] = clamp(y + m_crr[cr]); d[1] = clamp(y + ((m_crg[cr] + m_cbg[cb]) >> 16)); d[2] = clamp(y + m_cbb[cb]); d[3] = 255; d += 4; } s += 64 * 3; } } // YCbCr H2V1 (2x1:1:1, 4 m_blocks per MCU) to RGB void jpeg_decoder::H2V1Convert() { int row = m_max_mcu_y_size - m_mcu_lines_left; uint8* d0 = m_pScan_line_0; uint8* y = m_pSample_buf + row * 8; uint8* c = m_pSample_buf + 2 * 64 + row * 8; for (int i = m_max_mcus_per_row; i > 0; i--) { for (int l = 0; l < 2; l++) { for (int j = 0; j < 4; j++) { int cb = c[0]; int cr = c[64]; int rc = m_crr[cr]; int gc = ((m_crg[cr] + m_cbg[cb]) >> 16); int bc = m_cbb[cb]; int yy = y[j << 1]; d0[0] = clamp(yy + rc); d0[1] = clamp(yy + gc); d0[2] = clamp(yy + bc); d0[3] = 255; yy = y[(j << 1) + 1]; d0[4] = clamp(yy + rc); d0[5] = clamp(yy + gc); d0[6] = clamp(yy + bc); d0[7] = 255; d0 += 8; c++; } y += 64; } y += 64 * 4 - 64 * 2; c += 64 * 4 - 8; } } // YCbCr H2V1 (2x1:1:1, 4 m_blocks per MCU) to RGB void jpeg_decoder::H2V1ConvertFiltered() { const uint BLOCKS_PER_MCU = 4; int row = m_max_mcu_y_size - m_mcu_lines_left; uint8* d0 = m_pScan_line_0; const int half_image_x_size = (m_image_x_size == 1) ? 0 : (m_image_x_size >> 1) - 1; const int row_x8 = row * 8; for (int x = 0; x < m_image_x_size; x++) { int y = m_pSample_buf[check_sample_buf_ofs((x >> 4) * BLOCKS_PER_MCU * 64 + ((x & 8) ? 64 : 0) + (x & 7) + row_x8)]; int c_x0 = (x - 1) >> 1; int c_x1 = JPGD_MIN(c_x0 + 1, half_image_x_size); c_x0 = JPGD_MAX(c_x0, 0); int a = (c_x0 >> 3) * BLOCKS_PER_MCU * 64 + (c_x0 & 7) + row_x8 + 128; int cb0 = m_pSample_buf[check_sample_buf_ofs(a)]; int cr0 = m_pSample_buf[check_sample_buf_ofs(a + 64)]; int b = (c_x1 >> 3) * BLOCKS_PER_MCU * 64 + (c_x1 & 7) + row_x8 + 128; int cb1 = m_pSample_buf[check_sample_buf_ofs(b)]; int cr1 = m_pSample_buf[check_sample_buf_ofs(b + 64)]; int w0 = (x & 1) ? 3 : 1; int w1 = (x & 1) ? 1 : 3; int cb = (cb0 * w0 + cb1 * w1 + 2) >> 2; int cr = (cr0 * w0 + cr1 * w1 + 2) >> 2; int rc = m_crr[cr]; int gc = ((m_crg[cr] + m_cbg[cb]) >> 16); int bc = m_cbb[cb]; d0[0] = clamp(y + rc); d0[1] = clamp(y + gc); d0[2] = clamp(y + bc); d0[3] = 255; d0 += 4; } } // YCbCr H2V1 (1x2:1:1, 4 m_blocks per MCU) to RGB void jpeg_decoder::H1V2Convert() { int row = m_max_mcu_y_size - m_mcu_lines_left; uint8* d0 = m_pScan_line_0; uint8* d1 = m_pScan_line_1; uint8* y; uint8* c; if (row < 8) y = m_pSample_buf + row * 8; else y = m_pSample_buf + 64 * 1 + (row & 7) * 8; c = m_pSample_buf + 64 * 2 + (row >> 1) * 8; for (int i = m_max_mcus_per_row; i > 0; i--) { for (int j = 0; j < 8; j++) { int cb = c[0 + j]; int cr = c[64 + j]; int rc = m_crr[cr]; int gc = ((m_crg[cr] + m_cbg[cb]) >> 16); int bc = m_cbb[cb]; int yy = y[j]; d0[0] = clamp(yy + rc); d0[1] = clamp(yy + gc); d0[2] = clamp(yy + bc); d0[3] = 255; yy = y[8 + j]; d1[0] = clamp(yy + rc); d1[1] = clamp(yy + gc); d1[2] = clamp(yy + bc); d1[3] = 255; d0 += 4; d1 += 4; } y += 64 * 4; c += 64 * 4; } } // YCbCr H2V1 (1x2:1:1, 4 m_blocks per MCU) to RGB void jpeg_decoder::H1V2ConvertFiltered() { const uint BLOCKS_PER_MCU = 4; int y = m_image_y_size - m_total_lines_left; int row = y & 15; const int half_image_y_size = (m_image_y_size == 1) ? 0 : (m_image_y_size >> 1) - 1; uint8* d0 = m_pScan_line_0; const int w0 = (row & 1) ? 3 : 1; const int w1 = (row & 1) ? 1 : 3; int c_y0 = (y - 1) >> 1; int c_y1 = JPGD_MIN(c_y0 + 1, half_image_y_size); const uint8_t* p_YSamples = m_pSample_buf; const uint8_t* p_C0Samples = m_pSample_buf; if ((c_y0 >= 0) && (((row & 15) == 0) || ((row & 15) == 15)) && (m_total_lines_left > 1)) { assert(y > 0); assert(m_sample_buf_prev_valid); if ((row & 15) == 15) p_YSamples = m_pSample_buf_prev; p_C0Samples = m_pSample_buf_prev; } const int y_sample_base_ofs = ((row & 8) ? 64 : 0) + (row & 7) * 8; const int y0_base = (c_y0 & 7) * 8 + 128; const int y1_base = (c_y1 & 7) * 8 + 128; for (int x = 0; x < m_image_x_size; x++) { const int base_ofs = (x >> 3) * BLOCKS_PER_MCU * 64 + (x & 7); int y_sample = p_YSamples[check_sample_buf_ofs(base_ofs + y_sample_base_ofs)]; int a = base_ofs + y0_base; int cb0_sample = p_C0Samples[check_sample_buf_ofs(a)]; int cr0_sample = p_C0Samples[check_sample_buf_ofs(a + 64)]; int b = base_ofs + y1_base; int cb1_sample = m_pSample_buf[check_sample_buf_ofs(b)]; int cr1_sample = m_pSample_buf[check_sample_buf_ofs(b + 64)]; int cb = (cb0_sample * w0 + cb1_sample * w1 + 2) >> 2; int cr = (cr0_sample * w0 + cr1_sample * w1 + 2) >> 2; int rc = m_crr[cr]; int gc = ((m_crg[cr] + m_cbg[cb]) >> 16); int bc = m_cbb[cb]; d0[0] = clamp(y_sample + rc); d0[1] = clamp(y_sample + gc); d0[2] = clamp(y_sample + bc); d0[3] = 255; d0 += 4; } } // YCbCr H2V2 (2x2:1:1, 6 m_blocks per MCU) to RGB void jpeg_decoder::H2V2Convert() { int row = m_max_mcu_y_size - m_mcu_lines_left; uint8* d0 = m_pScan_line_0; uint8* d1 = m_pScan_line_1; uint8* y; uint8* c; if (row < 8) y = m_pSample_buf + row * 8; else y = m_pSample_buf + 64 * 2 + (row & 7) * 8; c = m_pSample_buf + 64 * 4 + (row >> 1) * 8; for (int i = m_max_mcus_per_row; i > 0; i--) { for (int l = 0; l < 2; l++) { for (int j = 0; j < 8; j += 2) { int cb = c[0]; int cr = c[64]; int rc = m_crr[cr]; int gc = ((m_crg[cr] + m_cbg[cb]) >> 16); int bc = m_cbb[cb]; int yy = y[j]; d0[0] = clamp(yy + rc); d0[1] = clamp(yy + gc); d0[2] = clamp(yy + bc); d0[3] = 255; yy = y[j + 1]; d0[4] = clamp(yy + rc); d0[5] = clamp(yy + gc); d0[6] = clamp(yy + bc); d0[7] = 255; yy = y[j + 8]; d1[0] = clamp(yy + rc); d1[1] = clamp(yy + gc); d1[2] = clamp(yy + bc); d1[3] = 255; yy = y[j + 8 + 1]; d1[4] = clamp(yy + rc); d1[5] = clamp(yy + gc); d1[6] = clamp(yy + bc); d1[7] = 255; d0 += 8; d1 += 8; c++; } y += 64; } y += 64 * 6 - 64 * 2; c += 64 * 6 - 8; } } uint32_t jpeg_decoder::H2V2ConvertFiltered() { const uint BLOCKS_PER_MCU = 6; int y = m_image_y_size - m_total_lines_left; int row = y & 15; const int half_image_y_size = (m_image_y_size == 1) ? 0 : (m_image_y_size >> 1) - 1; uint8* d0 = m_pScan_line_0; int c_y0 = (y - 1) >> 1; int c_y1 = JPGD_MIN(c_y0 + 1, half_image_y_size); const uint8_t* p_YSamples = m_pSample_buf; const uint8_t* p_C0Samples = m_pSample_buf; if ((c_y0 >= 0) && (((row & 15) == 0) || ((row & 15) == 15)) && (m_total_lines_left > 1)) { assert(y > 0); assert(m_sample_buf_prev_valid); if ((row & 15) == 15) p_YSamples = m_pSample_buf_prev; p_C0Samples = m_pSample_buf_prev; } const int y_sample_base_ofs = ((row & 8) ? 128 : 0) + (row & 7) * 8; const int y0_base = (c_y0 & 7) * 8 + 256; const int y1_base = (c_y1 & 7) * 8 + 256; const int half_image_x_size = (m_image_x_size == 1) ? 0 : (m_image_x_size >> 1) - 1; static const uint8_t s_muls[2][2][4] = { { { 1, 3, 3, 9 }, { 3, 9, 1, 3 }, }, { { 3, 1, 9, 3 }, { 9, 3, 3, 1 } } }; if (((row & 15) >= 1) && ((row & 15) <= 14)) { assert((row & 1) == 1); assert(((y + 1 - 1) >> 1) == c_y0); assert(p_YSamples == m_pSample_buf); assert(p_C0Samples == m_pSample_buf); uint8* d1 = m_pScan_line_1; const int y_sample_base_ofs1 = (((row + 1) & 8) ? 128 : 0) + ((row + 1) & 7) * 8; for (int x = 0; x < m_image_x_size; x++) { int k = (x >> 4) * BLOCKS_PER_MCU * 64 + ((x & 8) ? 64 : 0) + (x & 7); int y_sample0 = p_YSamples[check_sample_buf_ofs(k + y_sample_base_ofs)]; int y_sample1 = p_YSamples[check_sample_buf_ofs(k + y_sample_base_ofs1)]; int c_x0 = (x - 1) >> 1; int c_x1 = JPGD_MIN(c_x0 + 1, half_image_x_size); c_x0 = JPGD_MAX(c_x0, 0); int a = (c_x0 >> 3) * BLOCKS_PER_MCU * 64 + (c_x0 & 7); int cb00_sample = p_C0Samples[check_sample_buf_ofs(a + y0_base)]; int cr00_sample = p_C0Samples[check_sample_buf_ofs(a + y0_base + 64)]; int cb01_sample = m_pSample_buf[check_sample_buf_ofs(a + y1_base)]; int cr01_sample = m_pSample_buf[check_sample_buf_ofs(a + y1_base + 64)]; int b = (c_x1 >> 3) * BLOCKS_PER_MCU * 64 + (c_x1 & 7); int cb10_sample = p_C0Samples[check_sample_buf_ofs(b + y0_base)]; int cr10_sample = p_C0Samples[check_sample_buf_ofs(b + y0_base + 64)]; int cb11_sample = m_pSample_buf[check_sample_buf_ofs(b + y1_base)]; int cr11_sample = m_pSample_buf[check_sample_buf_ofs(b + y1_base + 64)]; { const uint8_t* pMuls = &s_muls[row & 1][x & 1][0]; int cb = (cb00_sample * pMuls[0] + cb01_sample * pMuls[1] + cb10_sample * pMuls[2] + cb11_sample * pMuls[3] + 8) >> 4; int cr = (cr00_sample * pMuls[0] + cr01_sample * pMuls[1] + cr10_sample * pMuls[2] + cr11_sample * pMuls[3] + 8) >> 4; int rc = m_crr[cr]; int gc = ((m_crg[cr] + m_cbg[cb]) >> 16); int bc = m_cbb[cb]; d0[0] = clamp(y_sample0 + rc); d0[1] = clamp(y_sample0 + gc); d0[2] = clamp(y_sample0 + bc); d0[3] = 255; d0 += 4; } { const uint8_t* pMuls = &s_muls[(row + 1) & 1][x & 1][0]; int cb = (cb00_sample * pMuls[0] + cb01_sample * pMuls[1] + cb10_sample * pMuls[2] + cb11_sample * pMuls[3] + 8) >> 4; int cr = (cr00_sample * pMuls[0] + cr01_sample * pMuls[1] + cr10_sample * pMuls[2] + cr11_sample * pMuls[3] + 8) >> 4; int rc = m_crr[cr]; int gc = ((m_crg[cr] + m_cbg[cb]) >> 16); int bc = m_cbb[cb]; d1[0] = clamp(y_sample1 + rc); d1[1] = clamp(y_sample1 + gc); d1[2] = clamp(y_sample1 + bc); d1[3] = 255; d1 += 4; } if (((x & 1) == 1) && (x < m_image_x_size - 1)) { const int nx = x + 1; assert(c_x0 == (nx - 1) >> 1); k = (nx >> 4) * BLOCKS_PER_MCU * 64 + ((nx & 8) ? 64 : 0) + (nx & 7); y_sample0 = p_YSamples[check_sample_buf_ofs(k + y_sample_base_ofs)]; y_sample1 = p_YSamples[check_sample_buf_ofs(k + y_sample_base_ofs1)]; { const uint8_t* pMuls = &s_muls[row & 1][nx & 1][0]; int cb = (cb00_sample * pMuls[0] + cb01_sample * pMuls[1] + cb10_sample * pMuls[2] + cb11_sample * pMuls[3] + 8) >> 4; int cr = (cr00_sample * pMuls[0] + cr01_sample * pMuls[1] + cr10_sample * pMuls[2] + cr11_sample * pMuls[3] + 8) >> 4; int rc = m_crr[cr]; int gc = ((m_crg[cr] + m_cbg[cb]) >> 16); int bc = m_cbb[cb]; d0[0] = clamp(y_sample0 + rc); d0[1] = clamp(y_sample0 + gc); d0[2] = clamp(y_sample0 + bc); d0[3] = 255; d0 += 4; } { const uint8_t* pMuls = &s_muls[(row + 1) & 1][nx & 1][0]; int cb = (cb00_sample * pMuls[0] + cb01_sample * pMuls[1] + cb10_sample * pMuls[2] + cb11_sample * pMuls[3] + 8) >> 4; int cr = (cr00_sample * pMuls[0] + cr01_sample * pMuls[1] + cr10_sample * pMuls[2] + cr11_sample * pMuls[3] + 8) >> 4; int rc = m_crr[cr]; int gc = ((m_crg[cr] + m_cbg[cb]) >> 16); int bc = m_cbb[cb]; d1[0] = clamp(y_sample1 + rc); d1[1] = clamp(y_sample1 + gc); d1[2] = clamp(y_sample1 + bc); d1[3] = 255; d1 += 4; } ++x; } } return 2; } else { for (int x = 0; x < m_image_x_size; x++) { int y_sample = p_YSamples[check_sample_buf_ofs((x >> 4) * BLOCKS_PER_MCU * 64 + ((x & 8) ? 64 : 0) + (x & 7) + y_sample_base_ofs)]; int c_x0 = (x - 1) >> 1; int c_x1 = JPGD_MIN(c_x0 + 1, half_image_x_size); c_x0 = JPGD_MAX(c_x0, 0); int a = (c_x0 >> 3) * BLOCKS_PER_MCU * 64 + (c_x0 & 7); int cb00_sample = p_C0Samples[check_sample_buf_ofs(a + y0_base)]; int cr00_sample = p_C0Samples[check_sample_buf_ofs(a + y0_base + 64)]; int cb01_sample = m_pSample_buf[check_sample_buf_ofs(a + y1_base)]; int cr01_sample = m_pSample_buf[check_sample_buf_ofs(a + y1_base + 64)]; int b = (c_x1 >> 3) * BLOCKS_PER_MCU * 64 + (c_x1 & 7); int cb10_sample = p_C0Samples[check_sample_buf_ofs(b + y0_base)]; int cr10_sample = p_C0Samples[check_sample_buf_ofs(b + y0_base + 64)]; int cb11_sample = m_pSample_buf[check_sample_buf_ofs(b + y1_base)]; int cr11_sample = m_pSample_buf[check_sample_buf_ofs(b + y1_base + 64)]; const uint8_t* pMuls = &s_muls[row & 1][x & 1][0]; int cb = (cb00_sample * pMuls[0] + cb01_sample * pMuls[1] + cb10_sample * pMuls[2] + cb11_sample * pMuls[3] + 8) >> 4; int cr = (cr00_sample * pMuls[0] + cr01_sample * pMuls[1] + cr10_sample * pMuls[2] + cr11_sample * pMuls[3] + 8) >> 4; int rc = m_crr[cr]; int gc = ((m_crg[cr] + m_cbg[cb]) >> 16); int bc = m_cbb[cb]; d0[0] = clamp(y_sample + rc); d0[1] = clamp(y_sample + gc); d0[2] = clamp(y_sample + bc); d0[3] = 255; d0 += 4; } return 1; } } // Y (1 block per MCU) to 8-bit grayscale void jpeg_decoder::gray_convert() { int row = m_max_mcu_y_size - m_mcu_lines_left; uint8* d = m_pScan_line_0; uint8* s = m_pSample_buf + row * 8; for (int i = m_max_mcus_per_row; i > 0; i--) { *(uint*)d = *(uint*)s; *(uint*)(&d[4]) = *(uint*)(&s[4]); s += 64; d += 8; } } // Find end of image (EOI) marker, so we can return to the user the exact size of the input stream. void jpeg_decoder::find_eoi() { if (!m_progressive_flag) { // Attempt to read the EOI marker. //get_bits_no_markers(m_bits_left & 7); // Prime the bit buffer m_bits_left = 16; get_bits(16); get_bits(16); // The next marker _should_ be EOI process_markers(); } m_total_bytes_read -= m_in_buf_left; } int jpeg_decoder::decode_next_mcu_row() { if (::setjmp(m_jmp_state)) return JPGD_FAILED; const bool chroma_y_filtering = ((m_flags & cFlagBoxChromaFiltering) == 0) && ((m_scan_type == JPGD_YH2V2) || (m_scan_type == JPGD_YH1V2)); if (chroma_y_filtering) { std::swap(m_pSample_buf, m_pSample_buf_prev); m_sample_buf_prev_valid = true; } if (m_progressive_flag) load_next_row(); else decode_next_row(); // Find the EOI marker if that was the last row. if (m_total_lines_left <= m_max_mcu_y_size) find_eoi(); m_mcu_lines_left = m_max_mcu_y_size; return 0; } int jpeg_decoder::decode(const void** pScan_line, uint* pScan_line_len) { if ((m_error_code) || (!m_ready_flag)) return JPGD_FAILED; if (m_total_lines_left == 0) return JPGD_DONE; const bool chroma_y_filtering = ((m_flags & cFlagBoxChromaFiltering) == 0) && ((m_scan_type == JPGD_YH2V2) || (m_scan_type == JPGD_YH1V2)); bool get_another_mcu_row = false; bool got_mcu_early = false; if (chroma_y_filtering) { if (m_total_lines_left == m_image_y_size) get_another_mcu_row = true; else if ((m_mcu_lines_left == 1) && (m_total_lines_left > 1)) { get_another_mcu_row = true; got_mcu_early = true; } } else { get_another_mcu_row = (m_mcu_lines_left == 0); } if (get_another_mcu_row) { int status = decode_next_mcu_row(); if (status != 0) return status; } switch (m_scan_type) { case JPGD_YH2V2: { if ((m_flags & cFlagBoxChromaFiltering) == 0) { if (m_num_buffered_scanlines == 1) { *pScan_line = m_pScan_line_1; } else if (m_num_buffered_scanlines == 0) { m_num_buffered_scanlines = H2V2ConvertFiltered(); *pScan_line = m_pScan_line_0; } m_num_buffered_scanlines--; } else { if ((m_mcu_lines_left & 1) == 0) { H2V2Convert(); *pScan_line = m_pScan_line_0; } else *pScan_line = m_pScan_line_1; } break; } case JPGD_YH2V1: { if ((m_flags & cFlagBoxChromaFiltering) == 0) H2V1ConvertFiltered(); else H2V1Convert(); *pScan_line = m_pScan_line_0; break; } case JPGD_YH1V2: { if (chroma_y_filtering) { H1V2ConvertFiltered(); *pScan_line = m_pScan_line_0; } else { if ((m_mcu_lines_left & 1) == 0) { H1V2Convert(); *pScan_line = m_pScan_line_0; } else *pScan_line = m_pScan_line_1; } break; } case JPGD_YH1V1: { H1V1Convert(); *pScan_line = m_pScan_line_0; break; } case JPGD_GRAYSCALE: { gray_convert(); *pScan_line = m_pScan_line_0; break; } } *pScan_line_len = m_real_dest_bytes_per_scan_line; if (!got_mcu_early) { m_mcu_lines_left--; } m_total_lines_left--; return JPGD_SUCCESS; } // Creates the tables needed for efficient Huffman decoding. void jpeg_decoder::make_huff_table(int index, huff_tables* pH) { int p, i, l, si; uint8 huffsize[258]; uint huffcode[258]; uint code; uint subtree; int code_size; int lastp; int nextfreeentry; int currententry; pH->ac_table = m_huff_ac[index] != 0; p = 0; for (l = 1; l <= 16; l++) { for (i = 1; i <= m_huff_num[index][l]; i++) { if (p >= 257) stop_decoding(JPGD_DECODE_ERROR); huffsize[p++] = static_cast<uint8>(l); } } assert(p < 258); huffsize[p] = 0; lastp = p; code = 0; si = huffsize[0]; p = 0; while (huffsize[p]) { while (huffsize[p] == si) { if (p >= 257) stop_decoding(JPGD_DECODE_ERROR); huffcode[p++] = code; code++; } code <<= 1; si++; } memset(pH->look_up, 0, sizeof(pH->look_up)); memset(pH->look_up2, 0, sizeof(pH->look_up2)); memset(pH->tree, 0, sizeof(pH->tree)); memset(pH->code_size, 0, sizeof(pH->code_size)); nextfreeentry = -1; p = 0; while (p < lastp) { i = m_huff_val[index][p]; code = huffcode[p]; code_size = huffsize[p]; assert(i < JPGD_HUFF_CODE_SIZE_MAX_LENGTH); pH->code_size[i] = static_cast<uint8>(code_size); if (code_size <= 8) { code <<= (8 - code_size); for (l = 1 << (8 - code_size); l > 0; l--) { if (code >= 256) stop_decoding(JPGD_DECODE_ERROR); pH->look_up[code] = i; bool has_extrabits = false; int extra_bits = 0; int num_extra_bits = i & 15; int bits_to_fetch = code_size; if (num_extra_bits) { int total_codesize = code_size + num_extra_bits; if (total_codesize <= 8) { has_extrabits = true; extra_bits = ((1 << num_extra_bits) - 1) & (code >> (8 - total_codesize)); if (extra_bits > 0x7FFF) stop_decoding(JPGD_DECODE_ERROR); bits_to_fetch += num_extra_bits; } } if (!has_extrabits) pH->look_up2[code] = i | (bits_to_fetch << 8); else pH->look_up2[code] = i | 0x8000 | (extra_bits << 16) | (bits_to_fetch << 8); code++; } } else { subtree = (code >> (code_size - 8)) & 0xFF; currententry = pH->look_up[subtree]; if (currententry == 0) { pH->look_up[subtree] = currententry = nextfreeentry; pH->look_up2[subtree] = currententry = nextfreeentry; nextfreeentry -= 2; } code <<= (16 - (code_size - 8)); for (l = code_size; l > 9; l--) { if ((code & 0x8000) == 0) currententry--; unsigned int idx = -currententry - 1; if (idx >= JPGD_HUFF_TREE_MAX_LENGTH) stop_decoding(JPGD_DECODE_ERROR); if (pH->tree[idx] == 0) { pH->tree[idx] = nextfreeentry; currententry = nextfreeentry; nextfreeentry -= 2; } else { currententry = pH->tree[idx]; } code <<= 1; } if ((code & 0x8000) == 0) currententry--; if ((-currententry - 1) >= JPGD_HUFF_TREE_MAX_LENGTH) stop_decoding(JPGD_DECODE_ERROR); pH->tree[-currententry - 1] = i; } p++; } } // Verifies the quantization tables needed for this scan are available. void jpeg_decoder::check_quant_tables() { for (int i = 0; i < m_comps_in_scan; i++) if (m_quant[m_comp_quant[m_comp_list[i]]] == nullptr) stop_decoding(JPGD_UNDEFINED_QUANT_TABLE); } // Verifies that all the Huffman tables needed for this scan are available. void jpeg_decoder::check_huff_tables() { for (int i = 0; i < m_comps_in_scan; i++) { if ((m_spectral_start == 0) && (m_huff_num[m_comp_dc_tab[m_comp_list[i]]] == nullptr)) stop_decoding(JPGD_UNDEFINED_HUFF_TABLE); if ((m_spectral_end > 0) && (m_huff_num[m_comp_ac_tab[m_comp_list[i]]] == nullptr)) stop_decoding(JPGD_UNDEFINED_HUFF_TABLE); } for (int i = 0; i < JPGD_MAX_HUFF_TABLES; i++) if (m_huff_num[i]) { if (!m_pHuff_tabs[i]) m_pHuff_tabs[i] = (huff_tables*)alloc(sizeof(huff_tables)); make_huff_table(i, m_pHuff_tabs[i]); } } // Determines the component order inside each MCU. // Also calcs how many MCU's are on each row, etc. bool jpeg_decoder::calc_mcu_block_order() { int component_num, component_id; int max_h_samp = 0, max_v_samp = 0; for (component_id = 0; component_id < m_comps_in_frame; component_id++) { if (m_comp_h_samp[component_id] > max_h_samp) max_h_samp = m_comp_h_samp[component_id]; if (m_comp_v_samp[component_id] > max_v_samp) max_v_samp = m_comp_v_samp[component_id]; } for (component_id = 0; component_id < m_comps_in_frame; component_id++) { m_comp_h_blocks[component_id] = ((((m_image_x_size * m_comp_h_samp[component_id]) + (max_h_samp - 1)) / max_h_samp) + 7) / 8; m_comp_v_blocks[component_id] = ((((m_image_y_size * m_comp_v_samp[component_id]) + (max_v_samp - 1)) / max_v_samp) + 7) / 8; } if (m_comps_in_scan == 1) { m_mcus_per_row = m_comp_h_blocks[m_comp_list[0]]; m_mcus_per_col = m_comp_v_blocks[m_comp_list[0]]; } else { m_mcus_per_row = (((m_image_x_size + 7) / 8) + (max_h_samp - 1)) / max_h_samp; m_mcus_per_col = (((m_image_y_size + 7) / 8) + (max_v_samp - 1)) / max_v_samp; } if (m_comps_in_scan == 1) { m_mcu_org[0] = m_comp_list[0]; m_blocks_per_mcu = 1; } else { m_blocks_per_mcu = 0; for (component_num = 0; component_num < m_comps_in_scan; component_num++) { int num_blocks; component_id = m_comp_list[component_num]; num_blocks = m_comp_h_samp[component_id] * m_comp_v_samp[component_id]; while (num_blocks--) m_mcu_org[m_blocks_per_mcu++] = component_id; } } if (m_blocks_per_mcu > m_max_blocks_per_mcu) return false; for (int mcu_block = 0; mcu_block < m_blocks_per_mcu; mcu_block++) { int comp_id = m_mcu_org[mcu_block]; if (comp_id >= JPGD_MAX_QUANT_TABLES) return false; } return true; } // Starts a new scan. int jpeg_decoder::init_scan() { if (!locate_sos_marker()) return JPGD_FALSE; if (!calc_mcu_block_order()) return JPGD_FALSE; check_huff_tables(); check_quant_tables(); memset(m_last_dc_val, 0, m_comps_in_frame * sizeof(uint)); m_eob_run = 0; if (m_restart_interval) { m_restarts_left = m_restart_interval; m_next_restart_num = 0; } fix_in_buffer(); return JPGD_TRUE; } // Starts a frame. Determines if the number of components or sampling factors // are supported. void jpeg_decoder::init_frame() { int i; if (m_comps_in_frame == 1) { if ((m_comp_h_samp[0] != 1) || (m_comp_v_samp[0] != 1)) stop_decoding(JPGD_UNSUPPORTED_SAMP_FACTORS); m_scan_type = JPGD_GRAYSCALE; m_max_blocks_per_mcu = 1; m_max_mcu_x_size = 8; m_max_mcu_y_size = 8; } else if (m_comps_in_frame == 3) { if (((m_comp_h_samp[1] != 1) || (m_comp_v_samp[1] != 1)) || ((m_comp_h_samp[2] != 1) || (m_comp_v_samp[2] != 1))) stop_decoding(JPGD_UNSUPPORTED_SAMP_FACTORS); if ((m_comp_h_samp[0] == 1) && (m_comp_v_samp[0] == 1)) { m_scan_type = JPGD_YH1V1; m_max_blocks_per_mcu = 3; m_max_mcu_x_size = 8; m_max_mcu_y_size = 8; } else if ((m_comp_h_samp[0] == 2) && (m_comp_v_samp[0] == 1)) { m_scan_type = JPGD_YH2V1; m_max_blocks_per_mcu = 4; m_max_mcu_x_size = 16; m_max_mcu_y_size = 8; } else if ((m_comp_h_samp[0] == 1) && (m_comp_v_samp[0] == 2)) { m_scan_type = JPGD_YH1V2; m_max_blocks_per_mcu = 4; m_max_mcu_x_size = 8; m_max_mcu_y_size = 16; } else if ((m_comp_h_samp[0] == 2) && (m_comp_v_samp[0] == 2)) { m_scan_type = JPGD_YH2V2; m_max_blocks_per_mcu = 6; m_max_mcu_x_size = 16; m_max_mcu_y_size = 16; } else stop_decoding(JPGD_UNSUPPORTED_SAMP_FACTORS); } else stop_decoding(JPGD_UNSUPPORTED_COLORSPACE); m_max_mcus_per_row = (m_image_x_size + (m_max_mcu_x_size - 1)) / m_max_mcu_x_size; m_max_mcus_per_col = (m_image_y_size + (m_max_mcu_y_size - 1)) / m_max_mcu_y_size; // These values are for the *destination* pixels: after conversion. if (m_scan_type == JPGD_GRAYSCALE) m_dest_bytes_per_pixel = 1; else m_dest_bytes_per_pixel = 4; m_dest_bytes_per_scan_line = ((m_image_x_size + 15) & 0xFFF0) * m_dest_bytes_per_pixel; m_real_dest_bytes_per_scan_line = (m_image_x_size * m_dest_bytes_per_pixel); // Initialize two scan line buffers. m_pScan_line_0 = (uint8*)alloc_aligned(m_dest_bytes_per_scan_line, true); if ((m_scan_type == JPGD_YH1V2) || (m_scan_type == JPGD_YH2V2)) m_pScan_line_1 = (uint8*)alloc_aligned(m_dest_bytes_per_scan_line, true); m_max_blocks_per_row = m_max_mcus_per_row * m_max_blocks_per_mcu; // Should never happen if (m_max_blocks_per_row > JPGD_MAX_BLOCKS_PER_ROW) stop_decoding(JPGD_DECODE_ERROR); // Allocate the coefficient buffer, enough for one MCU m_pMCU_coefficients = (jpgd_block_coeff_t *)alloc_aligned(m_max_blocks_per_mcu * 64 * sizeof(jpgd_block_coeff_t)); for (i = 0; i < m_max_blocks_per_mcu; i++) m_mcu_block_max_zag[i] = 64; m_pSample_buf = (uint8*)alloc_aligned(m_max_blocks_per_row * 64); m_pSample_buf_prev = (uint8*)alloc_aligned(m_max_blocks_per_row * 64); m_total_lines_left = m_image_y_size; m_mcu_lines_left = 0; create_look_ups(); } // The coeff_buf series of methods originally stored the coefficients // into a "virtual" file which was located in EMS, XMS, or a disk file. A cache // was used to make this process more efficient. Now, we can store the entire // thing in RAM. jpeg_decoder::coeff_buf* jpeg_decoder::coeff_buf_open(int block_num_x, int block_num_y, int block_len_x, int block_len_y) { coeff_buf* cb = (coeff_buf*)alloc(sizeof(coeff_buf)); cb->block_num_x = block_num_x; cb->block_num_y = block_num_y; cb->block_len_x = block_len_x; cb->block_len_y = block_len_y; cb->block_size = (block_len_x * block_len_y) * sizeof(jpgd_block_coeff_t); cb->pData = (uint8*)alloc(cb->block_size * block_num_x * block_num_y, true); return cb; } inline jpgd_block_coeff_t* jpeg_decoder::coeff_buf_getp(coeff_buf* cb, int block_x, int block_y) { if ((block_x >= cb->block_num_x) || (block_y >= cb->block_num_y)) stop_decoding(JPGD_DECODE_ERROR); return (jpgd_block_coeff_t*)(cb->pData + block_x * cb->block_size + block_y * (cb->block_size * cb->block_num_x)); } // The following methods decode the various types of m_blocks encountered // in progressively encoded images. void jpeg_decoder::decode_block_dc_first(jpeg_decoder* pD, int component_id, int block_x, int block_y) { int s, r; jpgd_block_coeff_t* p = pD->coeff_buf_getp(pD->m_dc_coeffs[component_id], block_x, block_y); if ((s = pD->huff_decode(pD->m_pHuff_tabs[pD->m_comp_dc_tab[component_id]])) != 0) { if (s >= 16) pD->stop_decoding(JPGD_DECODE_ERROR); r = pD->get_bits_no_markers(s); s = JPGD_HUFF_EXTEND(r, s); } pD->m_last_dc_val[component_id] = (s += pD->m_last_dc_val[component_id]); p[0] = static_cast<jpgd_block_coeff_t>(s << pD->m_successive_low); } void jpeg_decoder::decode_block_dc_refine(jpeg_decoder* pD, int component_id, int block_x, int block_y) { if (pD->get_bits_no_markers(1)) { jpgd_block_coeff_t* p = pD->coeff_buf_getp(pD->m_dc_coeffs[component_id], block_x, block_y); p[0] |= (1 << pD->m_successive_low); } } void jpeg_decoder::decode_block_ac_first(jpeg_decoder* pD, int component_id, int block_x, int block_y) { int k, s, r; if (pD->m_eob_run) { pD->m_eob_run--; return; } jpgd_block_coeff_t* p = pD->coeff_buf_getp(pD->m_ac_coeffs[component_id], block_x, block_y); for (k = pD->m_spectral_start; k <= pD->m_spectral_end; k++) { unsigned int idx = pD->m_comp_ac_tab[component_id]; if (idx >= JPGD_MAX_HUFF_TABLES) pD->stop_decoding(JPGD_DECODE_ERROR); s = pD->huff_decode(pD->m_pHuff_tabs[idx]); r = s >> 4; s &= 15; if (s) { if ((k += r) > 63) pD->stop_decoding(JPGD_DECODE_ERROR); r = pD->get_bits_no_markers(s); s = JPGD_HUFF_EXTEND(r, s); p[g_ZAG[k]] = static_cast<jpgd_block_coeff_t>(s << pD->m_successive_low); } else { if (r == 15) { if ((k += 15) > 63) pD->stop_decoding(JPGD_DECODE_ERROR); } else { pD->m_eob_run = 1 << r; if (r) pD->m_eob_run += pD->get_bits_no_markers(r); pD->m_eob_run--; break; } } } } void jpeg_decoder::decode_block_ac_refine(jpeg_decoder* pD, int component_id, int block_x, int block_y) { int s, k, r; int p1 = 1 << pD->m_successive_low; //int m1 = (-1) << pD->m_successive_low; int m1 = static_cast<int>((UINT32_MAX << pD->m_successive_low)); jpgd_block_coeff_t* p = pD->coeff_buf_getp(pD->m_ac_coeffs[component_id], block_x, block_y); if (pD->m_spectral_end > 63) pD->stop_decoding(JPGD_DECODE_ERROR); k = pD->m_spectral_start; if (pD->m_eob_run == 0) { for (; k <= pD->m_spectral_end; k++) { unsigned int idx = pD->m_comp_ac_tab[component_id]; if (idx >= JPGD_MAX_HUFF_TABLES) pD->stop_decoding(JPGD_DECODE_ERROR); s = pD->huff_decode(pD->m_pHuff_tabs[idx]); r = s >> 4; s &= 15; if (s) { if (s != 1) pD->stop_decoding(JPGD_DECODE_ERROR); if (pD->get_bits_no_markers(1)) s = p1; else s = m1; } else { if (r != 15) { pD->m_eob_run = 1 << r; if (r) pD->m_eob_run += pD->get_bits_no_markers(r); break; } } do { jpgd_block_coeff_t* this_coef = p + g_ZAG[k & 63]; if (*this_coef != 0) { if (pD->get_bits_no_markers(1)) { if ((*this_coef & p1) == 0) { if (*this_coef >= 0) *this_coef = static_cast<jpgd_block_coeff_t>(*this_coef + p1); else *this_coef = static_cast<jpgd_block_coeff_t>(*this_coef + m1); } } } else { if (--r < 0) break; } k++; } while (k <= pD->m_spectral_end); if ((s) && (k < 64)) { p[g_ZAG[k]] = static_cast<jpgd_block_coeff_t>(s); } } } if (pD->m_eob_run > 0) { for (; k <= pD->m_spectral_end; k++) { jpgd_block_coeff_t* this_coef = p + g_ZAG[k & 63]; // logical AND to shut up static code analysis if (*this_coef != 0) { if (pD->get_bits_no_markers(1)) { if ((*this_coef & p1) == 0) { if (*this_coef >= 0) *this_coef = static_cast<jpgd_block_coeff_t>(*this_coef + p1); else *this_coef = static_cast<jpgd_block_coeff_t>(*this_coef + m1); } } } } pD->m_eob_run--; } } // Decode a scan in a progressively encoded image. void jpeg_decoder::decode_scan(pDecode_block_func decode_block_func) { int mcu_row, mcu_col, mcu_block; int block_x_mcu[JPGD_MAX_COMPONENTS], block_y_mcu[JPGD_MAX_COMPONENTS]; memset(block_y_mcu, 0, sizeof(block_y_mcu)); for (mcu_col = 0; mcu_col < m_mcus_per_col; mcu_col++) { int component_num, component_id; memset(block_x_mcu, 0, sizeof(block_x_mcu)); for (mcu_row = 0; mcu_row < m_mcus_per_row; mcu_row++) { int block_x_mcu_ofs = 0, block_y_mcu_ofs = 0; if ((m_restart_interval) && (m_restarts_left == 0)) process_restart(); for (mcu_block = 0; mcu_block < m_blocks_per_mcu; mcu_block++) { component_id = m_mcu_org[mcu_block]; decode_block_func(this, component_id, block_x_mcu[component_id] + block_x_mcu_ofs, block_y_mcu[component_id] + block_y_mcu_ofs); if (m_comps_in_scan == 1) block_x_mcu[component_id]++; else { if (++block_x_mcu_ofs == m_comp_h_samp[component_id]) { block_x_mcu_ofs = 0; if (++block_y_mcu_ofs == m_comp_v_samp[component_id]) { block_y_mcu_ofs = 0; block_x_mcu[component_id] += m_comp_h_samp[component_id]; } } } } m_restarts_left--; } if (m_comps_in_scan == 1) block_y_mcu[m_comp_list[0]]++; else { for (component_num = 0; component_num < m_comps_in_scan; component_num++) { component_id = m_comp_list[component_num]; block_y_mcu[component_id] += m_comp_v_samp[component_id]; } } } } // Decode a progressively encoded image. void jpeg_decoder::init_progressive() { int i; if (m_comps_in_frame == 4) stop_decoding(JPGD_UNSUPPORTED_COLORSPACE); // Allocate the coefficient buffers. for (i = 0; i < m_comps_in_frame; i++) { m_dc_coeffs[i] = coeff_buf_open(m_max_mcus_per_row * m_comp_h_samp[i], m_max_mcus_per_col * m_comp_v_samp[i], 1, 1); m_ac_coeffs[i] = coeff_buf_open(m_max_mcus_per_row * m_comp_h_samp[i], m_max_mcus_per_col * m_comp_v_samp[i], 8, 8); } // See https://libjpeg-turbo.org/pmwiki/uploads/About/TwoIssueswiththeJPEGStandard.pdf uint32_t total_scans = 0; const uint32_t MAX_SCANS_TO_PROCESS = 1000; for (; ; ) { int dc_only_scan, refinement_scan; pDecode_block_func decode_block_func; if (!init_scan()) break; dc_only_scan = (m_spectral_start == 0); refinement_scan = (m_successive_high != 0); if ((m_spectral_start > m_spectral_end) || (m_spectral_end > 63)) stop_decoding(JPGD_BAD_SOS_SPECTRAL); if (dc_only_scan) { if (m_spectral_end) stop_decoding(JPGD_BAD_SOS_SPECTRAL); } else if (m_comps_in_scan != 1) /* AC scans can only contain one component */ stop_decoding(JPGD_BAD_SOS_SPECTRAL); if ((refinement_scan) && (m_successive_low != m_successive_high - 1)) stop_decoding(JPGD_BAD_SOS_SUCCESSIVE); if (dc_only_scan) { if (refinement_scan) decode_block_func = decode_block_dc_refine; else decode_block_func = decode_block_dc_first; } else { if (refinement_scan) decode_block_func = decode_block_ac_refine; else decode_block_func = decode_block_ac_first; } decode_scan(decode_block_func); m_bits_left = 16; get_bits(16); get_bits(16); total_scans++; if (total_scans > MAX_SCANS_TO_PROCESS) stop_decoding(JPGD_TOO_MANY_SCANS); } m_comps_in_scan = m_comps_in_frame; for (i = 0; i < m_comps_in_frame; i++) m_comp_list[i] = i; if (!calc_mcu_block_order()) stop_decoding(JPGD_DECODE_ERROR); } void jpeg_decoder::init_sequential() { if (!init_scan()) stop_decoding(JPGD_UNEXPECTED_MARKER); } void jpeg_decoder::decode_start() { init_frame(); if (m_progressive_flag) init_progressive(); else init_sequential(); } void jpeg_decoder::decode_init(jpeg_decoder_stream* pStream, uint32_t flags) { init(pStream, flags); locate_sof_marker(); } jpeg_decoder::jpeg_decoder(jpeg_decoder_stream* pStream, uint32_t flags) { if (::setjmp(m_jmp_state)) return; decode_init(pStream, flags); } int jpeg_decoder::begin_decoding() { if (m_ready_flag) return JPGD_SUCCESS; if (m_error_code) return JPGD_FAILED; if (::setjmp(m_jmp_state)) return JPGD_FAILED; decode_start(); m_ready_flag = true; return JPGD_SUCCESS; } jpeg_decoder::~jpeg_decoder() { free_all_blocks(); } jpeg_decoder_file_stream::jpeg_decoder_file_stream() { m_pFile = nullptr; m_eof_flag = false; m_error_flag = false; } void jpeg_decoder_file_stream::close() { if (m_pFile) { fclose(m_pFile); m_pFile = nullptr; } m_eof_flag = false; m_error_flag = false; } jpeg_decoder_file_stream::~jpeg_decoder_file_stream() { close(); } bool jpeg_decoder_file_stream::open(const char* Pfilename) { close(); m_eof_flag = false; m_error_flag = false; #if defined(_MSC_VER) m_pFile = nullptr; fopen_s(&m_pFile, Pfilename, "rb"); #else m_pFile = fopen(Pfilename, "rb"); #endif return m_pFile != nullptr; } int jpeg_decoder_file_stream::read(uint8* pBuf, int max_bytes_to_read, bool* pEOF_flag) { if (!m_pFile) return -1; if (m_eof_flag) { *pEOF_flag = true; return 0; } if (m_error_flag) return -1; int bytes_read = static_cast<int>(fread(pBuf, 1, max_bytes_to_read, m_pFile)); if (bytes_read < max_bytes_to_read) { if (ferror(m_pFile)) { m_error_flag = true; return -1; } m_eof_flag = true; *pEOF_flag = true; } return bytes_read; } bool jpeg_decoder_mem_stream::open(const uint8* pSrc_data, uint size) { close(); m_pSrc_data = pSrc_data; m_ofs = 0; m_size = size; return true; } int jpeg_decoder_mem_stream::read(uint8* pBuf, int max_bytes_to_read, bool* pEOF_flag) { *pEOF_flag = false; if (!m_pSrc_data) return -1; uint bytes_remaining = m_size - m_ofs; if ((uint)max_bytes_to_read > bytes_remaining) { max_bytes_to_read = bytes_remaining; *pEOF_flag = true; } memcpy(pBuf, m_pSrc_data + m_ofs, max_bytes_to_read); m_ofs += max_bytes_to_read; return max_bytes_to_read; } unsigned char* decompress_jpeg_image_from_stream(jpeg_decoder_stream* pStream, int* width, int* height, int* actual_comps, int req_comps, uint32_t flags) { if (!actual_comps) return nullptr; *actual_comps = 0; if ((!pStream) || (!width) || (!height) || (!req_comps)) return nullptr; if ((req_comps != 1) && (req_comps != 3) && (req_comps != 4)) return nullptr; jpeg_decoder decoder(pStream, flags); if (decoder.get_error_code() != JPGD_SUCCESS) return nullptr; const int image_width = decoder.get_width(), image_height = decoder.get_height(); *width = image_width; *height = image_height; *actual_comps = decoder.get_num_components(); if (decoder.begin_decoding() != JPGD_SUCCESS) return nullptr; const int dst_bpl = image_width * req_comps; uint8* pImage_data = (uint8*)jpgd_malloc(dst_bpl * image_height); if (!pImage_data) return nullptr; for (int y = 0; y < image_height; y++) { const uint8* pScan_line; uint scan_line_len; if (decoder.decode((const void**)&pScan_line, &scan_line_len) != JPGD_SUCCESS) { jpgd_free(pImage_data); return nullptr; } uint8* pDst = pImage_data + y * dst_bpl; if (((req_comps == 1) && (decoder.get_num_components() == 1)) || ((req_comps == 4) && (decoder.get_num_components() == 3))) memcpy(pDst, pScan_line, dst_bpl); else if (decoder.get_num_components() == 1) { if (req_comps == 3) { for (int x = 0; x < image_width; x++) { uint8 luma = pScan_line[x]; pDst[0] = luma; pDst[1] = luma; pDst[2] = luma; pDst += 3; } } else { for (int x = 0; x < image_width; x++) { uint8 luma = pScan_line[x]; pDst[0] = luma; pDst[1] = luma; pDst[2] = luma; pDst[3] = 255; pDst += 4; } } } else if (decoder.get_num_components() == 3) { if (req_comps == 1) { const int YR = 19595, YG = 38470, YB = 7471; for (int x = 0; x < image_width; x++) { int r = pScan_line[x * 4 + 0]; int g = pScan_line[x * 4 + 1]; int b = pScan_line[x * 4 + 2]; *pDst++ = static_cast<uint8>((r * YR + g * YG + b * YB + 32768) >> 16); } } else { for (int x = 0; x < image_width; x++) { pDst[0] = pScan_line[x * 4 + 0]; pDst[1] = pScan_line[x * 4 + 1]; pDst[2] = pScan_line[x * 4 + 2]; pDst += 3; } } } } return pImage_data; } unsigned char* decompress_jpeg_image_from_memory(const unsigned char* pSrc_data, int src_data_size, int* width, int* height, int* actual_comps, int req_comps, uint32_t flags) { jpgd::jpeg_decoder_mem_stream mem_stream(pSrc_data, src_data_size); return decompress_jpeg_image_from_stream(&mem_stream, width, height, actual_comps, req_comps, flags); } unsigned char* decompress_jpeg_image_from_file(const char* pSrc_filename, int* width, int* height, int* actual_comps, int req_comps, uint32_t flags) { jpgd::jpeg_decoder_file_stream file_stream; if (!file_stream.open(pSrc_filename)) return nullptr; return decompress_jpeg_image_from_stream(&file_stream, width, height, actual_comps, req_comps, flags); } } // namespace jpgd