summaryrefslogtreecommitdiff
path: root/drivers/webp/utils
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/webp/utils')
-rw-r--r--drivers/webp/utils/bit_reader_inl.h172
-rw-r--r--drivers/webp/utils/endian_inl.h100
-rw-r--r--drivers/webp/utils/quant_levels_dec.c279
-rw-r--r--drivers/webp/utils/quant_levels_dec.h35
-rw-r--r--drivers/webp/utils/random.c43
-rw-r--r--drivers/webp/utils/random.h63
6 files changed, 692 insertions, 0 deletions
diff --git a/drivers/webp/utils/bit_reader_inl.h b/drivers/webp/utils/bit_reader_inl.h
new file mode 100644
index 0000000000..37215702d4
--- /dev/null
+++ b/drivers/webp/utils/bit_reader_inl.h
@@ -0,0 +1,172 @@
+// Copyright 2014 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.
+// -----------------------------------------------------------------------------
+//
+// Specific inlined methods for boolean decoder [VP8GetBit() ...]
+// This file should be included by the .c sources that actually need to call
+// these methods.
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#ifndef WEBP_UTILS_BIT_READER_INL_H_
+#define WEBP_UTILS_BIT_READER_INL_H_
+
+#ifdef HAVE_CONFIG_H
+#include "../webp/config.h"
+#endif
+
+#ifdef WEBP_FORCE_ALIGNED
+#include <string.h> // memcpy
+#endif
+
+#include "../dsp/dsp.h"
+#include "./bit_reader.h"
+#include "./endian_inl.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+//------------------------------------------------------------------------------
+// Derived type lbit_t = natural type for memory I/O
+
+#if (BITS > 32)
+typedef uint64_t lbit_t;
+#elif (BITS > 16)
+typedef uint32_t lbit_t;
+#elif (BITS > 8)
+typedef uint16_t lbit_t;
+#else
+typedef uint8_t lbit_t;
+#endif
+
+extern const uint8_t kVP8Log2Range[128];
+extern const uint8_t kVP8NewRange[128];
+
+// special case for the tail byte-reading
+void VP8LoadFinalBytes(VP8BitReader* const br);
+
+//------------------------------------------------------------------------------
+// Inlined critical functions
+
+// makes sure br->value_ has at least BITS bits worth of data
+static WEBP_INLINE void VP8LoadNewBytes(VP8BitReader* const br) {
+ assert(br != NULL && br->buf_ != NULL);
+ // Read 'BITS' bits at a time if possible.
+ if (br->buf_ < br->buf_max_) {
+ // convert memory type to register type (with some zero'ing!)
+ bit_t bits;
+#if defined(WEBP_FORCE_ALIGNED)
+ lbit_t in_bits;
+ memcpy(&in_bits, br->buf_, sizeof(in_bits));
+#elif defined(WEBP_USE_MIPS32)
+ // This is needed because of un-aligned read.
+ lbit_t in_bits;
+ lbit_t* p_buf_ = (lbit_t*)br->buf_;
+ __asm__ volatile(
+ ".set push \n\t"
+ ".set at \n\t"
+ ".set macro \n\t"
+ "ulw %[in_bits], 0(%[p_buf_]) \n\t"
+ ".set pop \n\t"
+ : [in_bits]"=r"(in_bits)
+ : [p_buf_]"r"(p_buf_)
+ : "memory", "at"
+ );
+#else
+ const lbit_t in_bits = *(const lbit_t*)br->buf_;
+#endif
+ br->buf_ += BITS >> 3;
+#if !defined(WORDS_BIGENDIAN)
+#if (BITS > 32)
+ bits = BSwap64(in_bits);
+ bits >>= 64 - BITS;
+#elif (BITS >= 24)
+ bits = BSwap32(in_bits);
+ bits >>= (32 - BITS);
+#elif (BITS == 16)
+ bits = BSwap16(in_bits);
+#else // BITS == 8
+ bits = (bit_t)in_bits;
+#endif // BITS > 32
+#else // WORDS_BIGENDIAN
+ bits = (bit_t)in_bits;
+ if (BITS != 8 * sizeof(bit_t)) bits >>= (8 * sizeof(bit_t) - BITS);
+#endif
+ br->value_ = bits | (br->value_ << BITS);
+ br->bits_ += BITS;
+ } else {
+ VP8LoadFinalBytes(br); // no need to be inlined
+ }
+}
+
+// Read a bit with proba 'prob'. Speed-critical function!
+static WEBP_INLINE int VP8GetBit(VP8BitReader* const br, int prob) {
+ // Don't move this declaration! It makes a big speed difference to store
+ // 'range' *before* calling VP8LoadNewBytes(), even if this function doesn't
+ // alter br->range_ value.
+ range_t range = br->range_;
+ if (br->bits_ < 0) {
+ VP8LoadNewBytes(br);
+ }
+ {
+ const int pos = br->bits_;
+ const range_t split = (range * prob) >> 8;
+ const range_t value = (range_t)(br->value_ >> pos);
+#if defined(__arm__) || defined(_M_ARM) // ARM-specific
+ const int bit = ((int)(split - value) >> 31) & 1;
+ if (value > split) {
+ range -= split + 1;
+ br->value_ -= (bit_t)(split + 1) << pos;
+ } else {
+ range = split;
+ }
+#else // faster version on x86
+ int bit; // Don't use 'const int bit = (value > split);", it's slower.
+ if (value > split) {
+ range -= split + 1;
+ br->value_ -= (bit_t)(split + 1) << pos;
+ bit = 1;
+ } else {
+ range = split;
+ bit = 0;
+ }
+#endif
+ if (range <= (range_t)0x7e) {
+ const int shift = kVP8Log2Range[range];
+ range = kVP8NewRange[range];
+ br->bits_ -= shift;
+ }
+ br->range_ = range;
+ return bit;
+ }
+}
+
+// simplified version of VP8GetBit() for prob=0x80 (note shift is always 1 here)
+static WEBP_INLINE int VP8GetSigned(VP8BitReader* const br, int v) {
+ if (br->bits_ < 0) {
+ VP8LoadNewBytes(br);
+ }
+ {
+ const int pos = br->bits_;
+ const range_t split = br->range_ >> 1;
+ const range_t value = (range_t)(br->value_ >> pos);
+ const int32_t mask = (int32_t)(split - value) >> 31; // -1 or 0
+ br->bits_ -= 1;
+ br->range_ += mask;
+ br->range_ |= 1;
+ br->value_ -= (bit_t)((split + 1) & mask) << pos;
+ return (v ^ mask) - mask;
+ }
+}
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif // WEBP_UTILS_BIT_READER_INL_H_
diff --git a/drivers/webp/utils/endian_inl.h b/drivers/webp/utils/endian_inl.h
new file mode 100644
index 0000000000..e11260ff7d
--- /dev/null
+++ b/drivers/webp/utils/endian_inl.h
@@ -0,0 +1,100 @@
+// Copyright 2014 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.
+// -----------------------------------------------------------------------------
+//
+// Endian related functions.
+
+#ifndef WEBP_UTILS_ENDIAN_INL_H_
+#define WEBP_UTILS_ENDIAN_INL_H_
+
+#ifdef HAVE_CONFIG_H
+#include "../webp/config.h"
+#endif
+
+#include "../dsp/dsp.h"
+#include "../webp/types.h"
+
+// some endian fix (e.g.: mips-gcc doesn't define __BIG_ENDIAN__)
+#if !defined(WORDS_BIGENDIAN) && \
+ (defined(__BIG_ENDIAN__) || defined(_M_PPC) || \
+ (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)))
+#define WORDS_BIGENDIAN
+#endif
+
+#if defined(WORDS_BIGENDIAN)
+#define HToLE32 BSwap32
+#define HToLE16 BSwap16
+#else
+#define HToLE32(x) (x)
+#define HToLE16(x) (x)
+#endif
+
+#if !defined(HAVE_CONFIG_H)
+#if LOCAL_GCC_PREREQ(4,8) || __has_builtin(__builtin_bswap16)
+#define HAVE_BUILTIN_BSWAP16
+#endif
+#if LOCAL_GCC_PREREQ(4,3) || __has_builtin(__builtin_bswap32)
+#define HAVE_BUILTIN_BSWAP32
+#endif
+#if LOCAL_GCC_PREREQ(4,3) || __has_builtin(__builtin_bswap64)
+#define HAVE_BUILTIN_BSWAP64
+#endif
+#endif // !HAVE_CONFIG_H
+
+static WEBP_INLINE uint16_t BSwap16(uint16_t x) {
+#if defined(HAVE_BUILTIN_BSWAP16)
+ return __builtin_bswap16(x);
+#elif defined(_MSC_VER)
+ return _byteswap_ushort(x);
+#else
+ // gcc will recognize a 'rorw $8, ...' here:
+ return (x >> 8) | ((x & 0xff) << 8);
+#endif // HAVE_BUILTIN_BSWAP16
+}
+
+static WEBP_INLINE uint32_t BSwap32(uint32_t x) {
+#if defined(WEBP_USE_MIPS32_R2)
+ uint32_t ret;
+ __asm__ volatile (
+ "wsbh %[ret], %[x] \n\t"
+ "rotr %[ret], %[ret], 16 \n\t"
+ : [ret]"=r"(ret)
+ : [x]"r"(x)
+ );
+ return ret;
+#elif defined(HAVE_BUILTIN_BSWAP32)
+ return __builtin_bswap32(x);
+#elif defined(__i386__) || defined(__x86_64__)
+ uint32_t swapped_bytes;
+ __asm__ volatile("bswap %0" : "=r"(swapped_bytes) : "0"(x));
+ return swapped_bytes;
+#elif defined(_MSC_VER)
+ return (uint32_t)_byteswap_ulong(x);
+#else
+ return (x >> 24) | ((x >> 8) & 0xff00) | ((x << 8) & 0xff0000) | (x << 24);
+#endif // HAVE_BUILTIN_BSWAP32
+}
+
+static WEBP_INLINE uint64_t BSwap64(uint64_t x) {
+#if defined(HAVE_BUILTIN_BSWAP64)
+ return __builtin_bswap64(x);
+#elif defined(__x86_64__)
+ uint64_t swapped_bytes;
+ __asm__ volatile("bswapq %0" : "=r"(swapped_bytes) : "0"(x));
+ return swapped_bytes;
+#elif defined(_MSC_VER)
+ return (uint64_t)_byteswap_uint64(x);
+#else // generic code for swapping 64-bit values (suggested by bdb@)
+ x = ((x & 0xffffffff00000000ull) >> 32) | ((x & 0x00000000ffffffffull) << 32);
+ x = ((x & 0xffff0000ffff0000ull) >> 16) | ((x & 0x0000ffff0000ffffull) << 16);
+ x = ((x & 0xff00ff00ff00ff00ull) >> 8) | ((x & 0x00ff00ff00ff00ffull) << 8);
+ return x;
+#endif // HAVE_BUILTIN_BSWAP64
+}
+
+#endif // WEBP_UTILS_ENDIAN_INL_H_
diff --git a/drivers/webp/utils/quant_levels_dec.c b/drivers/webp/utils/quant_levels_dec.c
new file mode 100644
index 0000000000..5b8b8b49e6
--- /dev/null
+++ b/drivers/webp/utils/quant_levels_dec.c
@@ -0,0 +1,279 @@
+// Copyright 2013 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.
+// -----------------------------------------------------------------------------
+//
+// Implement gradient smoothing: we replace a current alpha value by its
+// surrounding average if it's close enough (that is: the change will be less
+// than the minimum distance between two quantized level).
+// We use sliding window for computing the 2d moving average.
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include "./quant_levels_dec.h"
+
+#include <string.h> // for memset
+
+#include "./utils.h"
+
+// #define USE_DITHERING // uncomment to enable ordered dithering (not vital)
+
+#define FIX 16 // fix-point precision for averaging
+#define LFIX 2 // extra precision for look-up table
+#define LUT_SIZE ((1 << (8 + LFIX)) - 1) // look-up table size
+
+#if defined(USE_DITHERING)
+
+#define DFIX 4 // extra precision for ordered dithering
+#define DSIZE 4 // dithering size (must be a power of two)
+// cf. http://en.wikipedia.org/wiki/Ordered_dithering
+static const uint8_t kOrderedDither[DSIZE][DSIZE] = {
+ { 0, 8, 2, 10 }, // coefficients are in DFIX fixed-point precision
+ { 12, 4, 14, 6 },
+ { 3, 11, 1, 9 },
+ { 15, 7, 13, 5 }
+};
+
+#else
+#define DFIX 0
+#endif
+
+typedef struct {
+ int width_, height_; // dimension
+ int row_; // current input row being processed
+ uint8_t* src_; // input pointer
+ uint8_t* dst_; // output pointer
+
+ int radius_; // filter radius (=delay)
+ int scale_; // normalization factor, in FIX bits precision
+
+ void* mem_; // all memory
+
+ // various scratch buffers
+ uint16_t* start_;
+ uint16_t* cur_;
+ uint16_t* end_;
+ uint16_t* top_;
+ uint16_t* average_;
+
+ // input levels distribution
+ int num_levels_; // number of quantized levels
+ int min_, max_; // min and max level values
+ int min_level_dist_; // smallest distance between two consecutive levels
+
+ int16_t* correction_; // size = 1 + 2*LUT_SIZE -> ~4k memory
+} SmoothParams;
+
+//------------------------------------------------------------------------------
+
+#define CLIP_MASK (int)(~0U << (8 + DFIX))
+static WEBP_INLINE uint8_t clip_8b(int v) {
+ return (!(v & CLIP_MASK)) ? (uint8_t)(v >> DFIX) : (v < 0) ? 0u : 255u;
+}
+
+// vertical accumulation
+static void VFilter(SmoothParams* const p) {
+ const uint8_t* src = p->src_;
+ const int w = p->width_;
+ uint16_t* const cur = p->cur_;
+ const uint16_t* const top = p->top_;
+ uint16_t* const out = p->end_;
+ uint16_t sum = 0; // all arithmetic is modulo 16bit
+ int x;
+
+ for (x = 0; x < w; ++x) {
+ uint16_t new_value;
+ sum += src[x];
+ new_value = top[x] + sum;
+ out[x] = new_value - cur[x]; // vertical sum of 'r' pixels.
+ cur[x] = new_value;
+ }
+ // move input pointers one row down
+ p->top_ = p->cur_;
+ p->cur_ += w;
+ if (p->cur_ == p->end_) p->cur_ = p->start_; // roll-over
+ // We replicate edges, as it's somewhat easier as a boundary condition.
+ // That's why we don't update the 'src' pointer on top/bottom area:
+ if (p->row_ >= 0 && p->row_ < p->height_ - 1) {
+ p->src_ += p->width_;
+ }
+}
+
+// horizontal accumulation. We use mirror replication of missing pixels, as it's
+// a little easier to implement (surprisingly).
+static void HFilter(SmoothParams* const p) {
+ const uint16_t* const in = p->end_;
+ uint16_t* const out = p->average_;
+ const uint32_t scale = p->scale_;
+ const int w = p->width_;
+ const int r = p->radius_;
+
+ int x;
+ for (x = 0; x <= r; ++x) { // left mirroring
+ const uint16_t delta = in[x + r - 1] + in[r - x];
+ out[x] = (delta * scale) >> FIX;
+ }
+ for (; x < w - r; ++x) { // bulk middle run
+ const uint16_t delta = in[x + r] - in[x - r - 1];
+ out[x] = (delta * scale) >> FIX;
+ }
+ for (; x < w; ++x) { // right mirroring
+ const uint16_t delta =
+ 2 * in[w - 1] - in[2 * w - 2 - r - x] - in[x - r - 1];
+ out[x] = (delta * scale) >> FIX;
+ }
+}
+
+// emit one filtered output row
+static void ApplyFilter(SmoothParams* const p) {
+ const uint16_t* const average = p->average_;
+ const int w = p->width_;
+ const int16_t* const correction = p->correction_;
+#if defined(USE_DITHERING)
+ const uint8_t* const dither = kOrderedDither[p->row_ % DSIZE];
+#endif
+ uint8_t* const dst = p->dst_;
+ int x;
+ for (x = 0; x < w; ++x) {
+ const int v = dst[x];
+ if (v < p->max_ && v > p->min_) {
+ const int c = (v << DFIX) + correction[average[x] - (v << LFIX)];
+#if defined(USE_DITHERING)
+ dst[x] = clip_8b(c + dither[x % DSIZE]);
+#else
+ dst[x] = clip_8b(c);
+#endif
+ }
+ }
+ p->dst_ += w; // advance output pointer
+}
+
+//------------------------------------------------------------------------------
+// Initialize correction table
+
+static void InitCorrectionLUT(int16_t* const lut, int min_dist) {
+ // The correction curve is:
+ // f(x) = x for x <= threshold2
+ // f(x) = 0 for x >= threshold1
+ // and a linear interpolation for range x=[threshold2, threshold1]
+ // (along with f(-x) = -f(x) symmetry).
+ // Note that: threshold2 = 3/4 * threshold1
+ const int threshold1 = min_dist << LFIX;
+ const int threshold2 = (3 * threshold1) >> 2;
+ const int max_threshold = threshold2 << DFIX;
+ const int delta = threshold1 - threshold2;
+ int i;
+ for (i = 1; i <= LUT_SIZE; ++i) {
+ int c = (i <= threshold2) ? (i << DFIX)
+ : (i < threshold1) ? max_threshold * (threshold1 - i) / delta
+ : 0;
+ c >>= LFIX;
+ lut[+i] = +c;
+ lut[-i] = -c;
+ }
+ lut[0] = 0;
+}
+
+static void CountLevels(const uint8_t* const data, int size,
+ SmoothParams* const p) {
+ int i, last_level;
+ uint8_t used_levels[256] = { 0 };
+ p->min_ = 255;
+ p->max_ = 0;
+ for (i = 0; i < size; ++i) {
+ const int v = data[i];
+ if (v < p->min_) p->min_ = v;
+ if (v > p->max_) p->max_ = v;
+ used_levels[v] = 1;
+ }
+ // Compute the mininum distance between two non-zero levels.
+ p->min_level_dist_ = p->max_ - p->min_;
+ last_level = -1;
+ for (i = 0; i < 256; ++i) {
+ if (used_levels[i]) {
+ ++p->num_levels_;
+ if (last_level >= 0) {
+ const int level_dist = i - last_level;
+ if (level_dist < p->min_level_dist_) {
+ p->min_level_dist_ = level_dist;
+ }
+ }
+ last_level = i;
+ }
+ }
+}
+
+// Initialize all params.
+static int InitParams(uint8_t* const data, int width, int height,
+ int radius, SmoothParams* const p) {
+ const int R = 2 * radius + 1; // total size of the kernel
+
+ const size_t size_scratch_m = (R + 1) * width * sizeof(*p->start_);
+ const size_t size_m = width * sizeof(*p->average_);
+ const size_t size_lut = (1 + 2 * LUT_SIZE) * sizeof(*p->correction_);
+ const size_t total_size = size_scratch_m + size_m + size_lut;
+ uint8_t* mem = (uint8_t*)WebPSafeMalloc(1U, total_size);
+
+ if (mem == NULL) return 0;
+ p->mem_ = (void*)mem;
+
+ p->start_ = (uint16_t*)mem;
+ p->cur_ = p->start_;
+ p->end_ = p->start_ + R * width;
+ p->top_ = p->end_ - width;
+ memset(p->top_, 0, width * sizeof(*p->top_));
+ mem += size_scratch_m;
+
+ p->average_ = (uint16_t*)mem;
+ mem += size_m;
+
+ p->width_ = width;
+ p->height_ = height;
+ p->src_ = data;
+ p->dst_ = data;
+ p->radius_ = radius;
+ p->scale_ = (1 << (FIX + LFIX)) / (R * R); // normalization constant
+ p->row_ = -radius;
+
+ // analyze the input distribution so we can best-fit the threshold
+ CountLevels(data, width * height, p);
+
+ // correction table
+ p->correction_ = ((int16_t*)mem) + LUT_SIZE;
+ InitCorrectionLUT(p->correction_, p->min_level_dist_);
+
+ return 1;
+}
+
+static void CleanupParams(SmoothParams* const p) {
+ WebPSafeFree(p->mem_);
+}
+
+int WebPDequantizeLevels(uint8_t* const data, int width, int height,
+ int strength) {
+ const int radius = 4 * strength / 100;
+ if (strength < 0 || strength > 100) return 0;
+ if (data == NULL || width <= 0 || height <= 0) return 0; // bad params
+ if (radius > 0) {
+ SmoothParams p;
+ memset(&p, 0, sizeof(p));
+ if (!InitParams(data, width, height, radius, &p)) return 0;
+ if (p.num_levels_ > 2) {
+ for (; p.row_ < p.height_; ++p.row_) {
+ VFilter(&p); // accumulate average of input
+ // Need to wait few rows in order to prime the filter,
+ // before emitting some output.
+ if (p.row_ >= p.radius_) {
+ HFilter(&p);
+ ApplyFilter(&p);
+ }
+ }
+ }
+ CleanupParams(&p);
+ }
+ return 1;
+}
diff --git a/drivers/webp/utils/quant_levels_dec.h b/drivers/webp/utils/quant_levels_dec.h
new file mode 100644
index 0000000000..9aab068076
--- /dev/null
+++ b/drivers/webp/utils/quant_levels_dec.h
@@ -0,0 +1,35 @@
+// Copyright 2013 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.
+// -----------------------------------------------------------------------------
+//
+// Alpha plane de-quantization utility
+//
+// Author: Vikas Arora (vikasa@google.com)
+
+#ifndef WEBP_UTILS_QUANT_LEVELS_DEC_H_
+#define WEBP_UTILS_QUANT_LEVELS_DEC_H_
+
+#include "../webp/types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Apply post-processing to input 'data' of size 'width'x'height' assuming that
+// the source was quantized to a reduced number of levels.
+// Strength is in [0..100] and controls the amount of dithering applied.
+// Returns false in case of error (data is NULL, invalid parameters,
+// malloc failure, ...).
+int WebPDequantizeLevels(uint8_t* const data, int width, int height,
+ int strength);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif /* WEBP_UTILS_QUANT_LEVELS_DEC_H_ */
diff --git a/drivers/webp/utils/random.c b/drivers/webp/utils/random.c
new file mode 100644
index 0000000000..24e96ad648
--- /dev/null
+++ b/drivers/webp/utils/random.c
@@ -0,0 +1,43 @@
+// Copyright 2013 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.
+// -----------------------------------------------------------------------------
+//
+// Pseudo-random utilities
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include <string.h>
+#include "./random.h"
+
+//------------------------------------------------------------------------------
+
+// 31b-range values
+static const uint32_t kRandomTable[VP8_RANDOM_TABLE_SIZE] = {
+ 0x0de15230, 0x03b31886, 0x775faccb, 0x1c88626a, 0x68385c55, 0x14b3b828,
+ 0x4a85fef8, 0x49ddb84b, 0x64fcf397, 0x5c550289, 0x4a290000, 0x0d7ec1da,
+ 0x5940b7ab, 0x5492577d, 0x4e19ca72, 0x38d38c69, 0x0c01ee65, 0x32a1755f,
+ 0x5437f652, 0x5abb2c32, 0x0faa57b1, 0x73f533e7, 0x685feeda, 0x7563cce2,
+ 0x6e990e83, 0x4730a7ed, 0x4fc0d9c6, 0x496b153c, 0x4f1403fa, 0x541afb0c,
+ 0x73990b32, 0x26d7cb1c, 0x6fcc3706, 0x2cbb77d8, 0x75762f2a, 0x6425ccdd,
+ 0x24b35461, 0x0a7d8715, 0x220414a8, 0x141ebf67, 0x56b41583, 0x73e502e3,
+ 0x44cab16f, 0x28264d42, 0x73baaefb, 0x0a50ebed, 0x1d6ab6fb, 0x0d3ad40b,
+ 0x35db3b68, 0x2b081e83, 0x77ce6b95, 0x5181e5f0, 0x78853bbc, 0x009f9494,
+ 0x27e5ed3c
+};
+
+void VP8InitRandom(VP8Random* const rg, float dithering) {
+ memcpy(rg->tab_, kRandomTable, sizeof(rg->tab_));
+ rg->index1_ = 0;
+ rg->index2_ = 31;
+ rg->amp_ = (dithering < 0.0) ? 0
+ : (dithering > 1.0) ? (1 << VP8_RANDOM_DITHER_FIX)
+ : (uint32_t)((1 << VP8_RANDOM_DITHER_FIX) * dithering);
+}
+
+//------------------------------------------------------------------------------
+
diff --git a/drivers/webp/utils/random.h b/drivers/webp/utils/random.h
new file mode 100644
index 0000000000..c392a615ca
--- /dev/null
+++ b/drivers/webp/utils/random.h
@@ -0,0 +1,63 @@
+// Copyright 2013 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.
+// -----------------------------------------------------------------------------
+//
+// Pseudo-random utilities
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#ifndef WEBP_UTILS_RANDOM_H_
+#define WEBP_UTILS_RANDOM_H_
+
+#include <assert.h>
+#include "../webp/types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define VP8_RANDOM_DITHER_FIX 8 // fixed-point precision for dithering
+#define VP8_RANDOM_TABLE_SIZE 55
+
+typedef struct {
+ int index1_, index2_;
+ uint32_t tab_[VP8_RANDOM_TABLE_SIZE];
+ int amp_;
+} VP8Random;
+
+// Initializes random generator with an amplitude 'dithering' in range [0..1].
+void VP8InitRandom(VP8Random* const rg, float dithering);
+
+// Returns a centered pseudo-random number with 'num_bits' amplitude.
+// (uses D.Knuth's Difference-based random generator).
+// 'amp' is in VP8_RANDOM_DITHER_FIX fixed-point precision.
+static WEBP_INLINE int VP8RandomBits2(VP8Random* const rg, int num_bits,
+ int amp) {
+ int diff;
+ assert(num_bits + VP8_RANDOM_DITHER_FIX <= 31);
+ diff = rg->tab_[rg->index1_] - rg->tab_[rg->index2_];
+ if (diff < 0) diff += (1u << 31);
+ rg->tab_[rg->index1_] = diff;
+ if (++rg->index1_ == VP8_RANDOM_TABLE_SIZE) rg->index1_ = 0;
+ if (++rg->index2_ == VP8_RANDOM_TABLE_SIZE) rg->index2_ = 0;
+ // sign-extend, 0-center
+ diff = (int)((uint32_t)diff << 1) >> (32 - num_bits);
+ diff = (diff * amp) >> VP8_RANDOM_DITHER_FIX; // restrict range
+ diff += 1 << (num_bits - 1); // shift back to 0.5-center
+ return diff;
+}
+
+static WEBP_INLINE int VP8RandomBits(VP8Random* const rg, int num_bits) {
+ return VP8RandomBits2(rg, num_bits, rg->amp_);
+}
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif /* WEBP_UTILS_RANDOM_H_ */
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-16 13:56:23 +0000