diff options
Diffstat (limited to 'drivers/webp/dec/vp8l.c')
| -rw-r--r-- | drivers/webp/dec/vp8l.c | 1380 |
1 files changed, 1380 insertions, 0 deletions
diff --git a/drivers/webp/dec/vp8l.c b/drivers/webp/dec/vp8l.c new file mode 100644 index 0000000000..ea0254d7a8 --- /dev/null +++ b/drivers/webp/dec/vp8l.c @@ -0,0 +1,1380 @@ +// Copyright 2012 Google Inc. All Rights Reserved. +// +// Use of this source code is governed by a BSD-style license +// that can be found in the COPYING file in the root of the source +// tree. An additional intellectual property rights grant can be found +// in the file PATENTS. All contributing project authors may +// be found in the AUTHORS file in the root of the source tree. +// ----------------------------------------------------------------------------- +// +// main entry for the decoder +// +// Authors: Vikas Arora (vikaas.arora@gmail.com) +// Jyrki Alakuijala (jyrki@google.com) + +#include <stdio.h> +#include <stdlib.h> +#include "./alphai.h" +#include "./vp8li.h" +#include "../dsp/lossless.h" +#include "../dsp/yuv.h" +#include "../utils/alpha_processing.h" +#include "../utils/huffman.h" +#include "../utils/utils.h" + +#define NUM_ARGB_CACHE_ROWS 16 + +static const int kCodeLengthLiterals = 16; +static const int kCodeLengthRepeatCode = 16; +static const int kCodeLengthExtraBits[3] = { 2, 3, 7 }; +static const int kCodeLengthRepeatOffsets[3] = { 3, 3, 11 }; + +// ----------------------------------------------------------------------------- +// Five Huffman codes are used at each meta code: +// 1. green + length prefix codes + color cache codes, +// 2. alpha, +// 3. red, +// 4. blue, and, +// 5. distance prefix codes. +typedef enum { + GREEN = 0, + RED = 1, + BLUE = 2, + ALPHA = 3, + DIST = 4 +} HuffIndex; + +static const uint16_t kAlphabetSize[HUFFMAN_CODES_PER_META_CODE] = { + NUM_LITERAL_CODES + NUM_LENGTH_CODES, + NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES, + NUM_DISTANCE_CODES +}; + + +#define NUM_CODE_LENGTH_CODES 19 +static const uint8_t kCodeLengthCodeOrder[NUM_CODE_LENGTH_CODES] = { + 17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 +}; + +#define CODE_TO_PLANE_CODES 120 +static const uint8_t kCodeToPlane[CODE_TO_PLANE_CODES] = { + 0x18, 0x07, 0x17, 0x19, 0x28, 0x06, 0x27, 0x29, 0x16, 0x1a, + 0x26, 0x2a, 0x38, 0x05, 0x37, 0x39, 0x15, 0x1b, 0x36, 0x3a, + 0x25, 0x2b, 0x48, 0x04, 0x47, 0x49, 0x14, 0x1c, 0x35, 0x3b, + 0x46, 0x4a, 0x24, 0x2c, 0x58, 0x45, 0x4b, 0x34, 0x3c, 0x03, + 0x57, 0x59, 0x13, 0x1d, 0x56, 0x5a, 0x23, 0x2d, 0x44, 0x4c, + 0x55, 0x5b, 0x33, 0x3d, 0x68, 0x02, 0x67, 0x69, 0x12, 0x1e, + 0x66, 0x6a, 0x22, 0x2e, 0x54, 0x5c, 0x43, 0x4d, 0x65, 0x6b, + 0x32, 0x3e, 0x78, 0x01, 0x77, 0x79, 0x53, 0x5d, 0x11, 0x1f, + 0x64, 0x6c, 0x42, 0x4e, 0x76, 0x7a, 0x21, 0x2f, 0x75, 0x7b, + 0x31, 0x3f, 0x63, 0x6d, 0x52, 0x5e, 0x00, 0x74, 0x7c, 0x41, + 0x4f, 0x10, 0x20, 0x62, 0x6e, 0x30, 0x73, 0x7d, 0x51, 0x5f, + 0x40, 0x72, 0x7e, 0x61, 0x6f, 0x50, 0x71, 0x7f, 0x60, 0x70 +}; + +static int DecodeImageStream(int xsize, int ysize, + int is_level0, + VP8LDecoder* const dec, + uint32_t** const decoded_data); + +//------------------------------------------------------------------------------ + +int VP8LCheckSignature(const uint8_t* const data, size_t size) { + return (size >= VP8L_FRAME_HEADER_SIZE && + data[0] == VP8L_MAGIC_BYTE && + (data[4] >> 5) == 0); // version +} + +static int ReadImageInfo(VP8LBitReader* const br, + int* const width, int* const height, + int* const has_alpha) { + if (VP8LReadBits(br, 8) != VP8L_MAGIC_BYTE) return 0; + *width = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1; + *height = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1; + *has_alpha = VP8LReadBits(br, 1); + if (VP8LReadBits(br, VP8L_VERSION_BITS) != 0) return 0; + return 1; +} + +int VP8LGetInfo(const uint8_t* data, size_t data_size, + int* const width, int* const height, int* const has_alpha) { + if (data == NULL || data_size < VP8L_FRAME_HEADER_SIZE) { + return 0; // not enough data + } else if (!VP8LCheckSignature(data, data_size)) { + return 0; // bad signature + } else { + int w, h, a; + VP8LBitReader br; + VP8LInitBitReader(&br, data, data_size); + if (!ReadImageInfo(&br, &w, &h, &a)) { + return 0; + } + if (width != NULL) *width = w; + if (height != NULL) *height = h; + if (has_alpha != NULL) *has_alpha = a; + return 1; + } +} + +//------------------------------------------------------------------------------ + +static WEBP_INLINE int GetCopyDistance(int distance_symbol, + VP8LBitReader* const br) { + int extra_bits, offset; + if (distance_symbol < 4) { + return distance_symbol + 1; + } + extra_bits = (distance_symbol - 2) >> 1; + offset = (2 + (distance_symbol & 1)) << extra_bits; + return offset + VP8LReadBits(br, extra_bits) + 1; +} + +static WEBP_INLINE int GetCopyLength(int length_symbol, + VP8LBitReader* const br) { + // Length and distance prefixes are encoded the same way. + return GetCopyDistance(length_symbol, br); +} + +static WEBP_INLINE int PlaneCodeToDistance(int xsize, int plane_code) { + if (plane_code > CODE_TO_PLANE_CODES) { + return plane_code - CODE_TO_PLANE_CODES; + } else { + const int dist_code = kCodeToPlane[plane_code - 1]; + const int yoffset = dist_code >> 4; + const int xoffset = 8 - (dist_code & 0xf); + const int dist = yoffset * xsize + xoffset; + return (dist >= 1) ? dist : 1; // dist<1 can happen if xsize is very small + } +} + +//------------------------------------------------------------------------------ +// Decodes the next Huffman code from bit-stream. +// FillBitWindow(br) needs to be called at minimum every second call +// to ReadSymbol, in order to pre-fetch enough bits. +static WEBP_INLINE int ReadSymbol(const HuffmanTree* tree, + VP8LBitReader* const br) { + const HuffmanTreeNode* node = tree->root_; + uint32_t bits = VP8LPrefetchBits(br); + int bitpos = br->bit_pos_; + // Check if we find the bit combination from the Huffman lookup table. + const int lut_ix = bits & (HUFF_LUT - 1); + const int lut_bits = tree->lut_bits_[lut_ix]; + if (lut_bits <= HUFF_LUT_BITS) { + VP8LSetBitPos(br, bitpos + lut_bits); + return tree->lut_symbol_[lut_ix]; + } + node += tree->lut_jump_[lut_ix]; + bitpos += HUFF_LUT_BITS; + bits >>= HUFF_LUT_BITS; + + // Decode the value from a binary tree. + assert(node != NULL); + do { + node = HuffmanTreeNextNode(node, bits & 1); + bits >>= 1; + ++bitpos; + } while (HuffmanTreeNodeIsNotLeaf(node)); + VP8LSetBitPos(br, bitpos); + return node->symbol_; +} + +static int ReadHuffmanCodeLengths( + VP8LDecoder* const dec, const int* const code_length_code_lengths, + int num_symbols, int* const code_lengths) { + int ok = 0; + VP8LBitReader* const br = &dec->br_; + int symbol; + int max_symbol; + int prev_code_len = DEFAULT_CODE_LENGTH; + HuffmanTree tree; + + if (!HuffmanTreeBuildImplicit(&tree, code_length_code_lengths, + NUM_CODE_LENGTH_CODES)) { + dec->status_ = VP8_STATUS_BITSTREAM_ERROR; + return 0; + } + + if (VP8LReadBits(br, 1)) { // use length + const int length_nbits = 2 + 2 * VP8LReadBits(br, 3); + max_symbol = 2 + VP8LReadBits(br, length_nbits); + if (max_symbol > num_symbols) { + dec->status_ = VP8_STATUS_BITSTREAM_ERROR; + goto End; + } + } else { + max_symbol = num_symbols; + } + + symbol = 0; + while (symbol < num_symbols) { + int code_len; + if (max_symbol-- == 0) break; + VP8LFillBitWindow(br); + code_len = ReadSymbol(&tree, br); + if (code_len < kCodeLengthLiterals) { + code_lengths[symbol++] = code_len; + if (code_len != 0) prev_code_len = code_len; + } else { + const int use_prev = (code_len == kCodeLengthRepeatCode); + const int slot = code_len - kCodeLengthLiterals; + const int extra_bits = kCodeLengthExtraBits[slot]; + const int repeat_offset = kCodeLengthRepeatOffsets[slot]; + int repeat = VP8LReadBits(br, extra_bits) + repeat_offset; + if (symbol + repeat > num_symbols) { + dec->status_ = VP8_STATUS_BITSTREAM_ERROR; + goto End; + } else { + const int length = use_prev ? prev_code_len : 0; + while (repeat-- > 0) code_lengths[symbol++] = length; + } + } + } + ok = 1; + + End: + HuffmanTreeRelease(&tree); + return ok; +} + +static int ReadHuffmanCode(int alphabet_size, VP8LDecoder* const dec, + HuffmanTree* const tree) { + int ok = 0; + VP8LBitReader* const br = &dec->br_; + const int simple_code = VP8LReadBits(br, 1); + + if (simple_code) { // Read symbols, codes & code lengths directly. + int symbols[2]; + int codes[2]; + int code_lengths[2]; + const int num_symbols = VP8LReadBits(br, 1) + 1; + const int first_symbol_len_code = VP8LReadBits(br, 1); + // The first code is either 1 bit or 8 bit code. + symbols[0] = VP8LReadBits(br, (first_symbol_len_code == 0) ? 1 : 8); + codes[0] = 0; + code_lengths[0] = num_symbols - 1; + // The second code (if present), is always 8 bit long. + if (num_symbols == 2) { + symbols[1] = VP8LReadBits(br, 8); + codes[1] = 1; + code_lengths[1] = num_symbols - 1; + } + ok = HuffmanTreeBuildExplicit(tree, code_lengths, codes, symbols, + alphabet_size, num_symbols); + } else { // Decode Huffman-coded code lengths. + int* code_lengths = NULL; + int i; + int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 }; + const int num_codes = VP8LReadBits(br, 4) + 4; + if (num_codes > NUM_CODE_LENGTH_CODES) { + dec->status_ = VP8_STATUS_BITSTREAM_ERROR; + return 0; + } + + code_lengths = + (int*)WebPSafeCalloc((uint64_t)alphabet_size, sizeof(*code_lengths)); + if (code_lengths == NULL) { + dec->status_ = VP8_STATUS_OUT_OF_MEMORY; + return 0; + } + + for (i = 0; i < num_codes; ++i) { + code_length_code_lengths[kCodeLengthCodeOrder[i]] = VP8LReadBits(br, 3); + } + ok = ReadHuffmanCodeLengths(dec, code_length_code_lengths, alphabet_size, + code_lengths); + if (ok) { + ok = HuffmanTreeBuildImplicit(tree, code_lengths, alphabet_size); + } + free(code_lengths); + } + ok = ok && !br->error_; + if (!ok) { + dec->status_ = VP8_STATUS_BITSTREAM_ERROR; + return 0; + } + return 1; +} + +static void DeleteHtreeGroups(HTreeGroup* htree_groups, int num_htree_groups) { + if (htree_groups != NULL) { + int i, j; + for (i = 0; i < num_htree_groups; ++i) { + HuffmanTree* const htrees = htree_groups[i].htrees_; + for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) { + HuffmanTreeRelease(&htrees[j]); + } + } + free(htree_groups); + } +} + +static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize, + int color_cache_bits, int allow_recursion) { + int i, j; + VP8LBitReader* const br = &dec->br_; + VP8LMetadata* const hdr = &dec->hdr_; + uint32_t* huffman_image = NULL; + HTreeGroup* htree_groups = NULL; + int num_htree_groups = 1; + + if (allow_recursion && VP8LReadBits(br, 1)) { + // use meta Huffman codes. + const int huffman_precision = VP8LReadBits(br, 3) + 2; + const int huffman_xsize = VP8LSubSampleSize(xsize, huffman_precision); + const int huffman_ysize = VP8LSubSampleSize(ysize, huffman_precision); + const int huffman_pixs = huffman_xsize * huffman_ysize; + if (!DecodeImageStream(huffman_xsize, huffman_ysize, 0, dec, + &huffman_image)) { + dec->status_ = VP8_STATUS_BITSTREAM_ERROR; + goto Error; + } + hdr->huffman_subsample_bits_ = huffman_precision; + for (i = 0; i < huffman_pixs; ++i) { + // The huffman data is stored in red and green bytes. + const int group = (huffman_image[i] >> 8) & 0xffff; + huffman_image[i] = group; + if (group >= num_htree_groups) { + num_htree_groups = group + 1; + } + } + } + + if (br->error_) goto Error; + + assert(num_htree_groups <= 0x10000); + htree_groups = + (HTreeGroup*)WebPSafeCalloc((uint64_t)num_htree_groups, + sizeof(*htree_groups)); + if (htree_groups == NULL) { + dec->status_ = VP8_STATUS_OUT_OF_MEMORY; + goto Error; + } + + for (i = 0; i < num_htree_groups; ++i) { + HuffmanTree* const htrees = htree_groups[i].htrees_; + for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) { + int alphabet_size = kAlphabetSize[j]; + if (j == 0 && color_cache_bits > 0) { + alphabet_size += 1 << color_cache_bits; + } + if (!ReadHuffmanCode(alphabet_size, dec, htrees + j)) goto Error; + } + } + + // All OK. Finalize pointers and return. + hdr->huffman_image_ = huffman_image; + hdr->num_htree_groups_ = num_htree_groups; + hdr->htree_groups_ = htree_groups; + return 1; + + Error: + free(huffman_image); + DeleteHtreeGroups(htree_groups, num_htree_groups); + return 0; +} + +//------------------------------------------------------------------------------ +// Scaling. + +static int AllocateAndInitRescaler(VP8LDecoder* const dec, VP8Io* const io) { + const int num_channels = 4; + const int in_width = io->mb_w; + const int out_width = io->scaled_width; + const int in_height = io->mb_h; + const int out_height = io->scaled_height; + const uint64_t work_size = 2 * num_channels * (uint64_t)out_width; + int32_t* work; // Rescaler work area. + const uint64_t scaled_data_size = num_channels * (uint64_t)out_width; + uint32_t* scaled_data; // Temporary storage for scaled BGRA data. + const uint64_t memory_size = sizeof(*dec->rescaler) + + work_size * sizeof(*work) + + scaled_data_size * sizeof(*scaled_data); + uint8_t* memory = (uint8_t*)WebPSafeCalloc(memory_size, sizeof(*memory)); + if (memory == NULL) { + dec->status_ = VP8_STATUS_OUT_OF_MEMORY; + return 0; + } + assert(dec->rescaler_memory == NULL); + dec->rescaler_memory = memory; + + dec->rescaler = (WebPRescaler*)memory; + memory += sizeof(*dec->rescaler); + work = (int32_t*)memory; + memory += work_size * sizeof(*work); + scaled_data = (uint32_t*)memory; + + WebPRescalerInit(dec->rescaler, in_width, in_height, (uint8_t*)scaled_data, + out_width, out_height, 0, num_channels, + in_width, out_width, in_height, out_height, work); + return 1; +} + +//------------------------------------------------------------------------------ +// Export to ARGB + +// We have special "export" function since we need to convert from BGRA +static int Export(WebPRescaler* const rescaler, WEBP_CSP_MODE colorspace, + int rgba_stride, uint8_t* const rgba) { + uint32_t* const src = (uint32_t*)rescaler->dst; + const int dst_width = rescaler->dst_width; + int num_lines_out = 0; + while (WebPRescalerHasPendingOutput(rescaler)) { + uint8_t* const dst = rgba + num_lines_out * rgba_stride; + WebPRescalerExportRow(rescaler); + WebPMultARGBRow(src, dst_width, 1); + VP8LConvertFromBGRA(src, dst_width, colorspace, dst); + ++num_lines_out; + } + return num_lines_out; +} + +// Emit scaled rows. +static int EmitRescaledRowsRGBA(const VP8LDecoder* const dec, + uint8_t* in, int in_stride, int mb_h, + uint8_t* const out, int out_stride) { + const WEBP_CSP_MODE colorspace = dec->output_->colorspace; + int num_lines_in = 0; + int num_lines_out = 0; + while (num_lines_in < mb_h) { + uint8_t* const row_in = in + num_lines_in * in_stride; + uint8_t* const row_out = out + num_lines_out * out_stride; + const int lines_left = mb_h - num_lines_in; + const int needed_lines = WebPRescaleNeededLines(dec->rescaler, lines_left); + assert(needed_lines > 0 && needed_lines <= lines_left); + WebPMultARGBRows(row_in, in_stride, + dec->rescaler->src_width, needed_lines, 0); + WebPRescalerImport(dec->rescaler, lines_left, row_in, in_stride); + num_lines_in += needed_lines; + num_lines_out += Export(dec->rescaler, colorspace, out_stride, row_out); + } + return num_lines_out; +} + +// Emit rows without any scaling. +static int EmitRows(WEBP_CSP_MODE colorspace, + const uint8_t* row_in, int in_stride, + int mb_w, int mb_h, + uint8_t* const out, int out_stride) { + int lines = mb_h; + uint8_t* row_out = out; + while (lines-- > 0) { + VP8LConvertFromBGRA((const uint32_t*)row_in, mb_w, colorspace, row_out); + row_in += in_stride; + row_out += out_stride; + } + return mb_h; // Num rows out == num rows in. +} + +//------------------------------------------------------------------------------ +// Export to YUVA + +static void ConvertToYUVA(const uint32_t* const src, int width, int y_pos, + const WebPDecBuffer* const output) { + const WebPYUVABuffer* const buf = &output->u.YUVA; + // first, the luma plane + { + int i; + uint8_t* const y = buf->y + y_pos * buf->y_stride; + for (i = 0; i < width; ++i) { + const uint32_t p = src[i]; + y[i] = VP8RGBToY((p >> 16) & 0xff, (p >> 8) & 0xff, (p >> 0) & 0xff, + YUV_HALF); + } + } + + // then U/V planes + { + uint8_t* const u = buf->u + (y_pos >> 1) * buf->u_stride; + uint8_t* const v = buf->v + (y_pos >> 1) * buf->v_stride; + const int uv_width = width >> 1; + int i; + for (i = 0; i < uv_width; ++i) { + const uint32_t v0 = src[2 * i + 0]; + const uint32_t v1 = src[2 * i + 1]; + // VP8RGBToU/V expects four accumulated pixels. Hence we need to + // scale r/g/b value by a factor 2. We just shift v0/v1 one bit less. + const int r = ((v0 >> 15) & 0x1fe) + ((v1 >> 15) & 0x1fe); + const int g = ((v0 >> 7) & 0x1fe) + ((v1 >> 7) & 0x1fe); + const int b = ((v0 << 1) & 0x1fe) + ((v1 << 1) & 0x1fe); + if (!(y_pos & 1)) { // even lines: store values + u[i] = VP8RGBToU(r, g, b, YUV_HALF << 2); + v[i] = VP8RGBToV(r, g, b, YUV_HALF << 2); + } else { // odd lines: average with previous values + const int tmp_u = VP8RGBToU(r, g, b, YUV_HALF << 2); + const int tmp_v = VP8RGBToV(r, g, b, YUV_HALF << 2); + // Approximated average-of-four. But it's an acceptable diff. + u[i] = (u[i] + tmp_u + 1) >> 1; + v[i] = (v[i] + tmp_v + 1) >> 1; + } + } + if (width & 1) { // last pixel + const uint32_t v0 = src[2 * i + 0]; + const int r = (v0 >> 14) & 0x3fc; + const int g = (v0 >> 6) & 0x3fc; + const int b = (v0 << 2) & 0x3fc; + if (!(y_pos & 1)) { // even lines + u[i] = VP8RGBToU(r, g, b, YUV_HALF << 2); + v[i] = VP8RGBToV(r, g, b, YUV_HALF << 2); + } else { // odd lines (note: we could just skip this) + const int tmp_u = VP8RGBToU(r, g, b, YUV_HALF << 2); + const int tmp_v = VP8RGBToV(r, g, b, YUV_HALF << 2); + u[i] = (u[i] + tmp_u + 1) >> 1; + v[i] = (v[i] + tmp_v + 1) >> 1; + } + } + } + // Lastly, store alpha if needed. + if (buf->a != NULL) { + int i; + uint8_t* const a = buf->a + y_pos * buf->a_stride; + for (i = 0; i < width; ++i) a[i] = (src[i] >> 24); + } +} + +static int ExportYUVA(const VP8LDecoder* const dec, int y_pos) { + WebPRescaler* const rescaler = dec->rescaler; + uint32_t* const src = (uint32_t*)rescaler->dst; + const int dst_width = rescaler->dst_width; + int num_lines_out = 0; + while (WebPRescalerHasPendingOutput(rescaler)) { + WebPRescalerExportRow(rescaler); + WebPMultARGBRow(src, dst_width, 1); + ConvertToYUVA(src, dst_width, y_pos, dec->output_); + ++y_pos; + ++num_lines_out; + } + return num_lines_out; +} + +static int EmitRescaledRowsYUVA(const VP8LDecoder* const dec, + uint8_t* in, int in_stride, int mb_h) { + int num_lines_in = 0; + int y_pos = dec->last_out_row_; + while (num_lines_in < mb_h) { + const int lines_left = mb_h - num_lines_in; + const int needed_lines = WebPRescaleNeededLines(dec->rescaler, lines_left); + WebPMultARGBRows(in, in_stride, dec->rescaler->src_width, needed_lines, 0); + WebPRescalerImport(dec->rescaler, lines_left, in, in_stride); + num_lines_in += needed_lines; + in += needed_lines * in_stride; + y_pos += ExportYUVA(dec, y_pos); + } + return y_pos; +} + +static int EmitRowsYUVA(const VP8LDecoder* const dec, + const uint8_t* in, int in_stride, + int mb_w, int num_rows) { + int y_pos = dec->last_out_row_; + while (num_rows-- > 0) { + ConvertToYUVA((const uint32_t*)in, mb_w, y_pos, dec->output_); + in += in_stride; + ++y_pos; + } + return y_pos; +} + +//------------------------------------------------------------------------------ +// Cropping. + +// Sets io->mb_y, io->mb_h & io->mb_w according to start row, end row and +// crop options. Also updates the input data pointer, so that it points to the +// start of the cropped window. Note that pixels are in ARGB format even if +// 'in_data' is uint8_t*. +// Returns true if the crop window is not empty. +static int SetCropWindow(VP8Io* const io, int y_start, int y_end, + uint8_t** const in_data, int pixel_stride) { + assert(y_start < y_end); + assert(io->crop_left < io->crop_right); + if (y_end > io->crop_bottom) { + y_end = io->crop_bottom; // make sure we don't overflow on last row. + } + if (y_start < io->crop_top) { + const int delta = io->crop_top - y_start; + y_start = io->crop_top; + *in_data += delta * pixel_stride; + } + if (y_start >= y_end) return 0; // Crop window is empty. + + *in_data += io->crop_left * sizeof(uint32_t); + + io->mb_y = y_start - io->crop_top; + io->mb_w = io->crop_right - io->crop_left; + io->mb_h = y_end - y_start; + return 1; // Non-empty crop window. +} + +//------------------------------------------------------------------------------ + +static WEBP_INLINE int GetMetaIndex( + const uint32_t* const image, int xsize, int bits, int x, int y) { + if (bits == 0) return 0; + return image[xsize * (y >> bits) + (x >> bits)]; +} + +static WEBP_INLINE HTreeGroup* GetHtreeGroupForPos(VP8LMetadata* const hdr, + int x, int y) { + const int meta_index = GetMetaIndex(hdr->huffman_image_, hdr->huffman_xsize_, + hdr->huffman_subsample_bits_, x, y); + assert(meta_index < hdr->num_htree_groups_); + return hdr->htree_groups_ + meta_index; +} + +//------------------------------------------------------------------------------ +// Main loop, with custom row-processing function + +typedef void (*ProcessRowsFunc)(VP8LDecoder* const dec, int row); + +static void ApplyInverseTransforms(VP8LDecoder* const dec, int num_rows, + const uint32_t* const rows) { + int n = dec->next_transform_; + const int cache_pixs = dec->width_ * num_rows; + const int start_row = dec->last_row_; + const int end_row = start_row + num_rows; + const uint32_t* rows_in = rows; + uint32_t* const rows_out = dec->argb_cache_; + + // Inverse transforms. + // TODO: most transforms only need to operate on the cropped region only. + memcpy(rows_out, rows_in, cache_pixs * sizeof(*rows_out)); + while (n-- > 0) { + VP8LTransform* const transform = &dec->transforms_[n]; + VP8LInverseTransform(transform, start_row, end_row, rows_in, rows_out); + rows_in = rows_out; + } +} + +// Special method for paletted alpha data. +static void ApplyInverseTransformsAlpha(VP8LDecoder* const dec, int num_rows, + const uint8_t* const rows) { + const int start_row = dec->last_row_; + const int end_row = start_row + num_rows; + const uint8_t* rows_in = rows; + uint8_t* rows_out = (uint8_t*)dec->io_->opaque + dec->io_->width * start_row; + VP8LTransform* const transform = &dec->transforms_[0]; + assert(dec->next_transform_ == 1); + assert(transform->type_ == COLOR_INDEXING_TRANSFORM); + VP8LColorIndexInverseTransformAlpha(transform, start_row, end_row, rows_in, + rows_out); +} + +// Processes (transforms, scales & color-converts) the rows decoded after the +// last call. +static void ProcessRows(VP8LDecoder* const dec, int row) { + const uint32_t* const rows = dec->pixels_ + dec->width_ * dec->last_row_; + const int num_rows = row - dec->last_row_; + + if (num_rows <= 0) return; // Nothing to be done. + ApplyInverseTransforms(dec, num_rows, rows); + + // Emit output. + { + VP8Io* const io = dec->io_; + uint8_t* rows_data = (uint8_t*)dec->argb_cache_; + const int in_stride = io->width * sizeof(uint32_t); // in unit of RGBA + if (!SetCropWindow(io, dec->last_row_, row, &rows_data, in_stride)) { + // Nothing to output (this time). + } else { + const WebPDecBuffer* const output = dec->output_; + if (output->colorspace < MODE_YUV) { // convert to RGBA + const WebPRGBABuffer* const buf = &output->u.RGBA; + uint8_t* const rgba = buf->rgba + dec->last_out_row_ * buf->stride; + const int num_rows_out = io->use_scaling ? + EmitRescaledRowsRGBA(dec, rows_data, in_stride, io->mb_h, + rgba, buf->stride) : + EmitRows(output->colorspace, rows_data, in_stride, + io->mb_w, io->mb_h, rgba, buf->stride); + // Update 'last_out_row_'. + dec->last_out_row_ += num_rows_out; + } else { // convert to YUVA + dec->last_out_row_ = io->use_scaling ? + EmitRescaledRowsYUVA(dec, rows_data, in_stride, io->mb_h) : + EmitRowsYUVA(dec, rows_data, in_stride, io->mb_w, io->mb_h); + } + assert(dec->last_out_row_ <= output->height); + } + } + + // Update 'last_row_'. + dec->last_row_ = row; + assert(dec->last_row_ <= dec->height_); +} + +// Row-processing for the special case when alpha data contains only one +// transform (color indexing), and trivial non-green literals. +static int Is8bOptimizable(const VP8LMetadata* const hdr) { + int i; + if (hdr->color_cache_size_ > 0) return 0; + // When the Huffman tree contains only one symbol, we can skip the + // call to ReadSymbol() for red/blue/alpha channels. + for (i = 0; i < hdr->num_htree_groups_; ++i) { + const HuffmanTree* const htrees = hdr->htree_groups_[i].htrees_; + if (htrees[RED].num_nodes_ > 1) return 0; + if (htrees[BLUE].num_nodes_ > 1) return 0; + if (htrees[ALPHA].num_nodes_ > 1) return 0; + } + return 1; +} + +static void ExtractPalettedAlphaRows(VP8LDecoder* const dec, int row) { + const int num_rows = row - dec->last_row_; + const uint8_t* const in = + (uint8_t*)dec->pixels_ + dec->width_ * dec->last_row_; + if (num_rows > 0) { + ApplyInverseTransformsAlpha(dec, num_rows, in); + } + dec->last_row_ = dec->last_out_row_ = row; +} + +static int DecodeAlphaData(VP8LDecoder* const dec, uint8_t* const data, + int width, int height, int last_row) { + int ok = 1; + int row = dec->last_pixel_ / width; + int col = dec->last_pixel_ % width; + VP8LBitReader* const br = &dec->br_; + VP8LMetadata* const hdr = &dec->hdr_; + const HTreeGroup* htree_group = GetHtreeGroupForPos(hdr, col, row); + int pos = dec->last_pixel_; // current position + const int end = width * height; // End of data + const int last = width * last_row; // Last pixel to decode + const int len_code_limit = NUM_LITERAL_CODES + NUM_LENGTH_CODES; + const int mask = hdr->huffman_mask_; + assert(htree_group != NULL); + assert(last_row <= height); + assert(Is8bOptimizable(hdr)); + + while (!br->eos_ && pos < last) { + int code; + // Only update when changing tile. + if ((col & mask) == 0) { + htree_group = GetHtreeGroupForPos(hdr, col, row); + } + VP8LFillBitWindow(br); + code = ReadSymbol(&htree_group->htrees_[GREEN], br); + if (code < NUM_LITERAL_CODES) { // Literal + data[pos] = code; + ++pos; + ++col; + if (col >= width) { + col = 0; + ++row; + if (row % NUM_ARGB_CACHE_ROWS == 0) { + ExtractPalettedAlphaRows(dec, row); + } + } + } else if (code < len_code_limit) { // Backward reference + int dist_code, dist; + const int length_sym = code - NUM_LITERAL_CODES; + const int length = GetCopyLength(length_sym, br); + const int dist_symbol = ReadSymbol(&htree_group->htrees_[DIST], br); + VP8LFillBitWindow(br); + dist_code = GetCopyDistance(dist_symbol, br); + dist = PlaneCodeToDistance(width, dist_code); + if (pos >= dist && end - pos >= length) { + int i; + for (i = 0; i < length; ++i) data[pos + i] = data[pos + i - dist]; + } else { + ok = 0; + goto End; + } + pos += length; + col += length; + while (col >= width) { + col -= width; + ++row; + if (row % NUM_ARGB_CACHE_ROWS == 0) { + ExtractPalettedAlphaRows(dec, row); + } + } + if (pos < last && (col & mask)) { + htree_group = GetHtreeGroupForPos(hdr, col, row); + } + } else { // Not reached + ok = 0; + goto End; + } + ok = !br->error_; + if (!ok) goto End; + } + // Process the remaining rows corresponding to last row-block. + ExtractPalettedAlphaRows(dec, row); + + End: + if (br->error_ || !ok || (br->eos_ && pos < end)) { + ok = 0; + dec->status_ = br->eos_ ? VP8_STATUS_SUSPENDED + : VP8_STATUS_BITSTREAM_ERROR; + } else { + dec->last_pixel_ = (int)pos; + if (pos == end) dec->state_ = READ_DATA; + } + return ok; +} + +static int DecodeImageData(VP8LDecoder* const dec, uint32_t* const data, + int width, int height, int last_row, + ProcessRowsFunc process_func) { + int ok = 1; + int row = dec->last_pixel_ / width; + int col = dec->last_pixel_ % width; + VP8LBitReader* const br = &dec->br_; + VP8LMetadata* const hdr = &dec->hdr_; + HTreeGroup* htree_group = GetHtreeGroupForPos(hdr, col, row); + uint32_t* src = data + dec->last_pixel_; + uint32_t* last_cached = src; + uint32_t* const src_end = data + width * height; // End of data + uint32_t* const src_last = data + width * last_row; // Last pixel to decode + const int len_code_limit = NUM_LITERAL_CODES + NUM_LENGTH_CODES; + const int color_cache_limit = len_code_limit + hdr->color_cache_size_; + VP8LColorCache* const color_cache = + (hdr->color_cache_size_ > 0) ? &hdr->color_cache_ : NULL; + const int mask = hdr->huffman_mask_; + assert(htree_group != NULL); + assert(src_last <= src_end); + + while (!br->eos_ && src < src_last) { + int code; + // Only update when changing tile. Note we could use this test: + // if "((((prev_col ^ col) | prev_row ^ row)) > mask)" -> tile changed + // but that's actually slower and needs storing the previous col/row. + if ((col & mask) == 0) { + htree_group = GetHtreeGroupForPos(hdr, col, row); + } + VP8LFillBitWindow(br); + code = ReadSymbol(&htree_group->htrees_[GREEN], br); + if (code < NUM_LITERAL_CODES) { // Literal + int red, green, blue, alpha; + red = ReadSymbol(&htree_group->htrees_[RED], br); + green = code; + VP8LFillBitWindow(br); + blue = ReadSymbol(&htree_group->htrees_[BLUE], br); + alpha = ReadSymbol(&htree_group->htrees_[ALPHA], br); + *src = (alpha << 24) | (red << 16) | (green << 8) | blue; + AdvanceByOne: + ++src; + ++col; + if (col >= width) { + col = 0; + ++row; + if ((row % NUM_ARGB_CACHE_ROWS == 0) && (process_func != NULL)) { + process_func(dec, row); + } + if (color_cache != NULL) { + while (last_cached < src) { + VP8LColorCacheInsert(color_cache, *last_cached++); + } + } + } + } else if (code < len_code_limit) { // Backward reference + int dist_code, dist; + const int length_sym = code - NUM_LITERAL_CODES; + const int length = GetCopyLength(length_sym, br); + const int dist_symbol = ReadSymbol(&htree_group->htrees_[DIST], br); + VP8LFillBitWindow(br); + dist_code = GetCopyDistance(dist_symbol, br); + dist = PlaneCodeToDistance(width, dist_code); + if (src - data < (ptrdiff_t)dist || src_end - src < (ptrdiff_t)length) { + ok = 0; + goto End; + } else { + int i; + for (i = 0; i < length; ++i) src[i] = src[i - dist]; + src += length; + } + col += length; + while (col >= width) { + col -= width; + ++row; + if ((row % NUM_ARGB_CACHE_ROWS == 0) && (process_func != NULL)) { + process_func(dec, row); + } + } + if (src < src_last) { + if (col & mask) htree_group = GetHtreeGroupForPos(hdr, col, row); + if (color_cache != NULL) { + while (last_cached < src) { + VP8LColorCacheInsert(color_cache, *last_cached++); + } + } + } + } else if (code < color_cache_limit) { // Color cache + const int key = code - len_code_limit; + assert(color_cache != NULL); + while (last_cached < src) { + VP8LColorCacheInsert(color_cache, *last_cached++); + } + *src = VP8LColorCacheLookup(color_cache, key); + goto AdvanceByOne; + } else { // Not reached + ok = 0; + goto End; + } + ok = !br->error_; + if (!ok) goto End; + } + // Process the remaining rows corresponding to last row-block. + if (process_func != NULL) process_func(dec, row); + + End: + if (br->error_ || !ok || (br->eos_ && src < src_end)) { + ok = 0; + dec->status_ = br->eos_ ? VP8_STATUS_SUSPENDED + : VP8_STATUS_BITSTREAM_ERROR; + } else { + dec->last_pixel_ = (int)(src - data); + if (src == src_end) dec->state_ = READ_DATA; + } + return ok; +} + +// ----------------------------------------------------------------------------- +// VP8LTransform + +static void ClearTransform(VP8LTransform* const transform) { + free(transform->data_); + transform->data_ = NULL; +} + +// For security reason, we need to remap the color map to span +// the total possible bundled values, and not just the num_colors. +static int ExpandColorMap(int num_colors, VP8LTransform* const transform) { + int i; + const int final_num_colors = 1 << (8 >> transform->bits_); + uint32_t* const new_color_map = + (uint32_t*)WebPSafeMalloc((uint64_t)final_num_colors, + sizeof(*new_color_map)); + if (new_color_map == NULL) { + return 0; + } else { + uint8_t* const data = (uint8_t*)transform->data_; + uint8_t* const new_data = (uint8_t*)new_color_map; + new_color_map[0] = transform->data_[0]; + for (i = 4; i < 4 * num_colors; ++i) { + // Equivalent to AddPixelEq(), on a byte-basis. + new_data[i] = (data[i] + new_data[i - 4]) & 0xff; + } + for (; i < 4 * final_num_colors; ++i) + new_data[i] = 0; // black tail. + free(transform->data_); + transform->data_ = new_color_map; + } + return 1; +} + +static int ReadTransform(int* const xsize, int const* ysize, + VP8LDecoder* const dec) { + int ok = 1; + VP8LBitReader* const br = &dec->br_; + VP8LTransform* transform = &dec->transforms_[dec->next_transform_]; + const VP8LImageTransformType type = + (VP8LImageTransformType)VP8LReadBits(br, 2); + + // Each transform type can only be present once in the stream. + if (dec->transforms_seen_ & (1U << type)) { + return 0; // Already there, let's not accept the second same transform. + } + dec->transforms_seen_ |= (1U << type); + + transform->type_ = type; + transform->xsize_ = *xsize; + transform->ysize_ = *ysize; + transform->data_ = NULL; + ++dec->next_transform_; + assert(dec->next_transform_ <= NUM_TRANSFORMS); + + switch (type) { + case PREDICTOR_TRANSFORM: + case CROSS_COLOR_TRANSFORM: + transform->bits_ = VP8LReadBits(br, 3) + 2; + ok = DecodeImageStream(VP8LSubSampleSize(transform->xsize_, + transform->bits_), + VP8LSubSampleSize(transform->ysize_, + transform->bits_), + 0, dec, &transform->data_); + break; + case COLOR_INDEXING_TRANSFORM: { + const int num_colors = VP8LReadBits(br, 8) + 1; + const int bits = (num_colors > 16) ? 0 + : (num_colors > 4) ? 1 + : (num_colors > 2) ? 2 + : 3; + *xsize = VP8LSubSampleSize(transform->xsize_, bits); + transform->bits_ = bits; + ok = DecodeImageStream(num_colors, 1, 0, dec, &transform->data_); + ok = ok && ExpandColorMap(num_colors, transform); + break; + } + case SUBTRACT_GREEN: + break; + default: + assert(0); // can't happen + break; + } + + return ok; +} + +// ----------------------------------------------------------------------------- +// VP8LMetadata + +static void InitMetadata(VP8LMetadata* const hdr) { + assert(hdr); + memset(hdr, 0, sizeof(*hdr)); +} + +static void ClearMetadata(VP8LMetadata* const hdr) { + assert(hdr); + + free(hdr->huffman_image_); + DeleteHtreeGroups(hdr->htree_groups_, hdr->num_htree_groups_); + VP8LColorCacheClear(&hdr->color_cache_); + InitMetadata(hdr); +} + +// ----------------------------------------------------------------------------- +// VP8LDecoder + +VP8LDecoder* VP8LNew(void) { + VP8LDecoder* const dec = (VP8LDecoder*)calloc(1, sizeof(*dec)); + if (dec == NULL) return NULL; + dec->status_ = VP8_STATUS_OK; + dec->action_ = READ_DIM; + dec->state_ = READ_DIM; + + VP8LDspInit(); // Init critical function pointers. + + return dec; +} + +void VP8LClear(VP8LDecoder* const dec) { + int i; + if (dec == NULL) return; + ClearMetadata(&dec->hdr_); + + free(dec->pixels_); + dec->pixels_ = NULL; + for (i = 0; i < dec->next_transform_; ++i) { + ClearTransform(&dec->transforms_[i]); + } + dec->next_transform_ = 0; + dec->transforms_seen_ = 0; + + free(dec->rescaler_memory); + dec->rescaler_memory = NULL; + + dec->output_ = NULL; // leave no trace behind +} + +void VP8LDelete(VP8LDecoder* const dec) { + if (dec != NULL) { + VP8LClear(dec); + free(dec); + } +} + +static void UpdateDecoder(VP8LDecoder* const dec, int width, int height) { + VP8LMetadata* const hdr = &dec->hdr_; + const int num_bits = hdr->huffman_subsample_bits_; + dec->width_ = width; + dec->height_ = height; + + hdr->huffman_xsize_ = VP8LSubSampleSize(width, num_bits); + hdr->huffman_mask_ = (num_bits == 0) ? ~0 : (1 << num_bits) - 1; +} + +static int DecodeImageStream(int xsize, int ysize, + int is_level0, + VP8LDecoder* const dec, + uint32_t** const decoded_data) { + int ok = 1; + int transform_xsize = xsize; + int transform_ysize = ysize; + VP8LBitReader* const br = &dec->br_; + VP8LMetadata* const hdr = &dec->hdr_; + uint32_t* data = NULL; + int color_cache_bits = 0; + + // Read the transforms (may recurse). + if (is_level0) { + while (ok && VP8LReadBits(br, 1)) { + ok = ReadTransform(&transform_xsize, &transform_ysize, dec); + } + } + + // Color cache + if (ok && VP8LReadBits(br, 1)) { + color_cache_bits = VP8LReadBits(br, 4); + ok = (color_cache_bits >= 1 && color_cache_bits <= MAX_CACHE_BITS); + if (!ok) { + dec->status_ = VP8_STATUS_BITSTREAM_ERROR; + goto End; + } + } + + // Read the Huffman codes (may recurse). + ok = ok && ReadHuffmanCodes(dec, transform_xsize, transform_ysize, + color_cache_bits, is_level0); + if (!ok) { + dec->status_ = VP8_STATUS_BITSTREAM_ERROR; + goto End; + } + + // Finish setting up the color-cache + if (color_cache_bits > 0) { + hdr->color_cache_size_ = 1 << color_cache_bits; + if (!VP8LColorCacheInit(&hdr->color_cache_, color_cache_bits)) { + dec->status_ = VP8_STATUS_OUT_OF_MEMORY; + ok = 0; + goto End; + } + } else { + hdr->color_cache_size_ = 0; + } + UpdateDecoder(dec, transform_xsize, transform_ysize); + + if (is_level0) { // level 0 complete + dec->state_ = READ_HDR; + goto End; + } + + { + const uint64_t total_size = (uint64_t)transform_xsize * transform_ysize; + data = (uint32_t*)WebPSafeMalloc(total_size, sizeof(*data)); + if (data == NULL) { + dec->status_ = VP8_STATUS_OUT_OF_MEMORY; + ok = 0; + goto End; + } + } + + // Use the Huffman trees to decode the LZ77 encoded data. + ok = DecodeImageData(dec, data, transform_xsize, transform_ysize, + transform_ysize, NULL); + ok = ok && !br->error_; + + End: + + if (!ok) { + free(data); + ClearMetadata(hdr); + // If not enough data (br.eos_) resulted in BIT_STREAM_ERROR, update the + // status appropriately. + if (dec->status_ == VP8_STATUS_BITSTREAM_ERROR && dec->br_.eos_) { + dec->status_ = VP8_STATUS_SUSPENDED; + } + } else { + if (decoded_data != NULL) { + *decoded_data = data; + } else { + // We allocate image data in this function only for transforms. At level 0 + // (that is: not the transforms), we shouldn't have allocated anything. + assert(data == NULL); + assert(is_level0); + } + dec->last_pixel_ = 0; // Reset for future DECODE_DATA_FUNC() calls. + if (!is_level0) ClearMetadata(hdr); // Clean up temporary data behind. + } + return ok; +} + +//------------------------------------------------------------------------------ +// Allocate internal buffers dec->pixels_ and dec->argb_cache_. +static int AllocateInternalBuffers32b(VP8LDecoder* const dec, int final_width) { + const uint64_t num_pixels = (uint64_t)dec->width_ * dec->height_; + // Scratch buffer corresponding to top-prediction row for transforming the + // first row in the row-blocks. Not needed for paletted alpha. + const uint64_t cache_top_pixels = (uint16_t)final_width; + // Scratch buffer for temporary BGRA storage. Not needed for paletted alpha. + const uint64_t cache_pixels = (uint64_t)final_width * NUM_ARGB_CACHE_ROWS; + const uint64_t total_num_pixels = + num_pixels + cache_top_pixels + cache_pixels; + + assert(dec->width_ <= final_width); + dec->pixels_ = (uint32_t*)WebPSafeMalloc(total_num_pixels, sizeof(uint32_t)); + if (dec->pixels_ == NULL) { + dec->argb_cache_ = NULL; // for sanity check + dec->status_ = VP8_STATUS_OUT_OF_MEMORY; + return 0; + } + dec->argb_cache_ = dec->pixels_ + num_pixels + cache_top_pixels; + return 1; +} + +static int AllocateInternalBuffers8b(VP8LDecoder* const dec) { + const uint64_t total_num_pixels = (uint64_t)dec->width_ * dec->height_; + dec->argb_cache_ = NULL; // for sanity check + dec->pixels_ = (uint32_t*)WebPSafeMalloc(total_num_pixels, sizeof(uint8_t)); + if (dec->pixels_ == NULL) { + dec->status_ = VP8_STATUS_OUT_OF_MEMORY; + return 0; + } + return 1; +} + +//------------------------------------------------------------------------------ + +// Special row-processing that only stores the alpha data. +static void ExtractAlphaRows(VP8LDecoder* const dec, int row) { + const int num_rows = row - dec->last_row_; + const uint32_t* const in = dec->pixels_ + dec->width_ * dec->last_row_; + + if (num_rows <= 0) return; // Nothing to be done. + ApplyInverseTransforms(dec, num_rows, in); + + // Extract alpha (which is stored in the green plane). + { + const int width = dec->io_->width; // the final width (!= dec->width_) + const int cache_pixs = width * num_rows; + uint8_t* const dst = (uint8_t*)dec->io_->opaque + width * dec->last_row_; + const uint32_t* const src = dec->argb_cache_; + int i; + for (i = 0; i < cache_pixs; ++i) dst[i] = (src[i] >> 8) & 0xff; + } + dec->last_row_ = dec->last_out_row_ = row; +} + +int VP8LDecodeAlphaHeader(ALPHDecoder* const alph_dec, + const uint8_t* const data, size_t data_size, + uint8_t* const output) { + int ok = 0; + VP8LDecoder* dec; + VP8Io* io; + assert(alph_dec != NULL); + alph_dec->vp8l_dec_ = VP8LNew(); + if (alph_dec->vp8l_dec_ == NULL) return 0; + dec = alph_dec->vp8l_dec_; + + dec->width_ = alph_dec->width_; + dec->height_ = alph_dec->height_; + dec->io_ = &alph_dec->io_; + io = dec->io_; + + VP8InitIo(io); + WebPInitCustomIo(NULL, io); // Just a sanity Init. io won't be used. + io->opaque = output; + io->width = alph_dec->width_; + io->height = alph_dec->height_; + + dec->status_ = VP8_STATUS_OK; + VP8LInitBitReader(&dec->br_, data, data_size); + + dec->action_ = READ_HDR; + if (!DecodeImageStream(alph_dec->width_, alph_dec->height_, 1, dec, NULL)) { + goto Err; + } + + // Special case: if alpha data uses only the color indexing transform and + // doesn't use color cache (a frequent case), we will use DecodeAlphaData() + // method that only needs allocation of 1 byte per pixel (alpha channel). + if (dec->next_transform_ == 1 && + dec->transforms_[0].type_ == COLOR_INDEXING_TRANSFORM && + Is8bOptimizable(&dec->hdr_)) { + alph_dec->use_8b_decode = 1; + ok = AllocateInternalBuffers8b(dec); + } else { + // Allocate internal buffers (note that dec->width_ may have changed here). + alph_dec->use_8b_decode = 0; + ok = AllocateInternalBuffers32b(dec, alph_dec->width_); + } + + if (!ok) goto Err; + + dec->action_ = READ_DATA; + return 1; + + Err: + VP8LDelete(alph_dec->vp8l_dec_); + alph_dec->vp8l_dec_ = NULL; + return 0; +} + +int VP8LDecodeAlphaImageStream(ALPHDecoder* const alph_dec, int last_row) { + VP8LDecoder* const dec = alph_dec->vp8l_dec_; + assert(dec != NULL); + assert(dec->action_ == READ_DATA); + assert(last_row <= dec->height_); + + // Decode (with special row processing). + return alph_dec->use_8b_decode ? + DecodeAlphaData(dec, (uint8_t*)dec->pixels_, dec->width_, dec->height_, + last_row) : + DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_, + last_row, ExtractAlphaRows); +} + +//------------------------------------------------------------------------------ + +int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io) { + int width, height, has_alpha; + + if (dec == NULL) return 0; + if (io == NULL) { + dec->status_ = VP8_STATUS_INVALID_PARAM; + return 0; + } + + dec->io_ = io; + dec->status_ = VP8_STATUS_OK; + VP8LInitBitReader(&dec->br_, io->data, io->data_size); + if (!ReadImageInfo(&dec->br_, &width, &height, &has_alpha)) { + dec->status_ = VP8_STATUS_BITSTREAM_ERROR; + goto Error; + } + dec->state_ = READ_DIM; + io->width = width; + io->height = height; + + dec->action_ = READ_HDR; + if (!DecodeImageStream(width, height, 1, dec, NULL)) goto Error; + return 1; + + Error: + VP8LClear(dec); + assert(dec->status_ != VP8_STATUS_OK); + return 0; +} + +int VP8LDecodeImage(VP8LDecoder* const dec) { + VP8Io* io = NULL; + WebPDecParams* params = NULL; + + // Sanity checks. + if (dec == NULL) return 0; + + io = dec->io_; + assert(io != NULL); + params = (WebPDecParams*)io->opaque; + assert(params != NULL); + dec->output_ = params->output; + assert(dec->output_ != NULL); + + // Initialization. + if (!WebPIoInitFromOptions(params->options, io, MODE_BGRA)) { + dec->status_ = VP8_STATUS_INVALID_PARAM; + goto Err; + } + + if (!AllocateInternalBuffers32b(dec, io->width)) goto Err; + + if (io->use_scaling && !AllocateAndInitRescaler(dec, io)) goto Err; + + // Decode. + dec->action_ = READ_DATA; + if (!DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_, + dec->height_, ProcessRows)) { + goto Err; + } + + // Cleanup. + params->last_y = dec->last_out_row_; + VP8LClear(dec); + return 1; + + Err: + VP8LClear(dec); + assert(dec->status_ != VP8_STATUS_OK); + return 0; +} + +//------------------------------------------------------------------------------ + |