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      1 // Copyright 2011 Google Inc. All Rights Reserved.
      2 //
      3 // Use of this source code is governed by a BSD-style license
      4 // that can be found in the COPYING file in the root of the source
      5 // tree. An additional intellectual property rights grant can be found
      6 // in the file PATENTS. All contributing project authors may
      7 // be found in the AUTHORS file in the root of the source tree.
      8 // -----------------------------------------------------------------------------
      9 //
     10 //   Speed-critical functions.
     11 //
     12 // Author: Skal (pascal.massimino (at) gmail.com)
     13 
     14 #ifndef WEBP_DSP_DSP_H_
     15 #define WEBP_DSP_DSP_H_
     16 
     17 #ifdef HAVE_CONFIG_H
     18 #include "src/webp/config.h"
     19 #endif
     20 
     21 #include "src/webp/types.h"
     22 
     23 #ifdef __cplusplus
     24 extern "C" {
     25 #endif
     26 
     27 #define BPS 32   // this is the common stride for enc/dec
     28 
     29 //------------------------------------------------------------------------------
     30 // CPU detection
     31 
     32 #if defined(__GNUC__)
     33 # define LOCAL_GCC_VERSION ((__GNUC__ << 8) | __GNUC_MINOR__)
     34 # define LOCAL_GCC_PREREQ(maj, min) \
     35     (LOCAL_GCC_VERSION >= (((maj) << 8) | (min)))
     36 #else
     37 # define LOCAL_GCC_VERSION 0
     38 # define LOCAL_GCC_PREREQ(maj, min) 0
     39 #endif
     40 
     41 #if defined(__clang__)
     42 # define LOCAL_CLANG_VERSION ((__clang_major__ << 8) | __clang_minor__)
     43 # define LOCAL_CLANG_PREREQ(maj, min) \
     44     (LOCAL_CLANG_VERSION >= (((maj) << 8) | (min)))
     45 #else
     46 # define LOCAL_CLANG_VERSION 0
     47 # define LOCAL_CLANG_PREREQ(maj, min) 0
     48 #endif
     49 
     50 #ifndef __has_builtin
     51 # define __has_builtin(x) 0
     52 #endif
     53 
     54 // for now, none of the optimizations below are available in emscripten
     55 #if !defined(EMSCRIPTEN)
     56 
     57 #if defined(_MSC_VER) && _MSC_VER > 1310 && \
     58     (defined(_M_X64) || defined(_M_IX86))
     59 #define WEBP_MSC_SSE2  // Visual C++ SSE2 targets
     60 #endif
     61 
     62 #if defined(_MSC_VER) && _MSC_VER >= 1500 && \
     63     (defined(_M_X64) || defined(_M_IX86))
     64 #define WEBP_MSC_SSE41  // Visual C++ SSE4.1 targets
     65 #endif
     66 
     67 // WEBP_HAVE_* are used to indicate the presence of the instruction set in dsp
     68 // files without intrinsics, allowing the corresponding Init() to be called.
     69 // Files containing intrinsics will need to be built targeting the instruction
     70 // set so should succeed on one of the earlier tests.
     71 #if defined(__SSE2__) || defined(WEBP_MSC_SSE2) || defined(WEBP_HAVE_SSE2)
     72 #define WEBP_USE_SSE2
     73 #endif
     74 
     75 #if defined(__SSE4_1__) || defined(WEBP_MSC_SSE41) || defined(WEBP_HAVE_SSE41)
     76 #define WEBP_USE_SSE41
     77 #endif
     78 
     79 // The intrinsics currently cause compiler errors with arm-nacl-gcc and the
     80 // inline assembly would need to be modified for use with Native Client.
     81 #if (defined(__ARM_NEON__) || \
     82      defined(__aarch64__) || defined(WEBP_HAVE_NEON)) && \
     83     !defined(__native_client__)
     84 #define WEBP_USE_NEON
     85 #endif
     86 
     87 #if !defined(WEBP_USE_NEON) && defined(__ANDROID__) && \
     88     defined(__ARM_ARCH_7A__) && defined(HAVE_CPU_FEATURES_H)
     89 #define WEBP_ANDROID_NEON  // Android targets that may have NEON
     90 #define WEBP_USE_NEON
     91 #endif
     92 
     93 #if defined(_MSC_VER) && _MSC_VER >= 1700 && defined(_M_ARM)
     94 #define WEBP_USE_NEON
     95 #define WEBP_USE_INTRINSICS
     96 #endif
     97 
     98 #if defined(__mips__) && !defined(__mips64) && \
     99     defined(__mips_isa_rev) && (__mips_isa_rev >= 1) && (__mips_isa_rev < 6)
    100 #define WEBP_USE_MIPS32
    101 #if (__mips_isa_rev >= 2)
    102 #define WEBP_USE_MIPS32_R2
    103 #if defined(__mips_dspr2) || (defined(__mips_dsp_rev) && __mips_dsp_rev >= 2)
    104 #define WEBP_USE_MIPS_DSP_R2
    105 #endif
    106 #endif
    107 #endif
    108 
    109 #if defined(__mips_msa) && defined(__mips_isa_rev) && (__mips_isa_rev >= 5)
    110 #define WEBP_USE_MSA
    111 #endif
    112 
    113 #endif  /* EMSCRIPTEN */
    114 
    115 #ifndef WEBP_DSP_OMIT_C_CODE
    116 #define WEBP_DSP_OMIT_C_CODE 1
    117 #endif
    118 
    119 #if (defined(__aarch64__) || defined(__ARM_NEON__)) && WEBP_DSP_OMIT_C_CODE
    120 #define WEBP_NEON_OMIT_C_CODE 1
    121 #else
    122 #define WEBP_NEON_OMIT_C_CODE 0
    123 #endif
    124 
    125 #if !(LOCAL_CLANG_PREREQ(3,8) || LOCAL_GCC_PREREQ(4,8) || defined(__aarch64__))
    126 #define WEBP_NEON_WORK_AROUND_GCC 1
    127 #else
    128 #define WEBP_NEON_WORK_AROUND_GCC 0
    129 #endif
    130 
    131 // This macro prevents thread_sanitizer from reporting known concurrent writes.
    132 #define WEBP_TSAN_IGNORE_FUNCTION
    133 #if defined(__has_feature)
    134 #if __has_feature(thread_sanitizer)
    135 #undef WEBP_TSAN_IGNORE_FUNCTION
    136 #define WEBP_TSAN_IGNORE_FUNCTION __attribute__((no_sanitize_thread))
    137 #endif
    138 #endif
    139 
    140 #if defined(WEBP_USE_THREAD) && !defined(_WIN32)
    141 #include <pthread.h>  // NOLINT
    142 
    143 #define WEBP_DSP_INIT(func) do {                                    \
    144   static volatile VP8CPUInfo func ## _last_cpuinfo_used =           \
    145       (VP8CPUInfo)&func ## _last_cpuinfo_used;                      \
    146   static pthread_mutex_t func ## _lock = PTHREAD_MUTEX_INITIALIZER; \
    147   if (pthread_mutex_lock(&func ## _lock)) break;                    \
    148   if (func ## _last_cpuinfo_used != VP8GetCPUInfo) func();          \
    149   func ## _last_cpuinfo_used = VP8GetCPUInfo;                       \
    150   (void)pthread_mutex_unlock(&func ## _lock);                       \
    151 } while (0)
    152 #else  // !(defined(WEBP_USE_THREAD) && !defined(_WIN32))
    153 #define WEBP_DSP_INIT(func) do {                                    \
    154   static volatile VP8CPUInfo func ## _last_cpuinfo_used =           \
    155       (VP8CPUInfo)&func ## _last_cpuinfo_used;                      \
    156   if (func ## _last_cpuinfo_used == VP8GetCPUInfo) break;           \
    157   func();                                                           \
    158   func ## _last_cpuinfo_used = VP8GetCPUInfo;                       \
    159 } while (0)
    160 #endif  // defined(WEBP_USE_THREAD) && !defined(_WIN32)
    161 
    162 // Defines an Init + helper function that control multiple initialization of
    163 // function pointers / tables.
    164 /* Usage:
    165    WEBP_DSP_INIT_FUNC(InitFunc) {
    166      ...function body
    167    }
    168 */
    169 #define WEBP_DSP_INIT_FUNC(name)                             \
    170   static WEBP_TSAN_IGNORE_FUNCTION void name ## _body(void); \
    171   WEBP_TSAN_IGNORE_FUNCTION void name(void) {                \
    172     WEBP_DSP_INIT(name ## _body);                            \
    173   }                                                          \
    174   static WEBP_TSAN_IGNORE_FUNCTION void name ## _body(void)
    175 
    176 #define WEBP_UBSAN_IGNORE_UNDEF
    177 #define WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW
    178 #if defined(__clang__) && defined(__has_attribute)
    179 #if __has_attribute(no_sanitize)
    180 // This macro prevents the undefined behavior sanitizer from reporting
    181 // failures. This is only meant to silence unaligned loads on platforms that
    182 // are known to support them.
    183 #undef WEBP_UBSAN_IGNORE_UNDEF
    184 #define WEBP_UBSAN_IGNORE_UNDEF \
    185   __attribute__((no_sanitize("undefined")))
    186 
    187 // This macro prevents the undefined behavior sanitizer from reporting
    188 // failures related to unsigned integer overflows. This is only meant to
    189 // silence cases where this well defined behavior is expected.
    190 #undef WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW
    191 #define WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW \
    192   __attribute__((no_sanitize("unsigned-integer-overflow")))
    193 #endif
    194 #endif
    195 
    196 // Regularize the definition of WEBP_SWAP_16BIT_CSP (backward compatibility)
    197 #if !defined(WEBP_SWAP_16BIT_CSP)
    198 #define WEBP_SWAP_16BIT_CSP 0
    199 #endif
    200 
    201 // some endian fix (e.g.: mips-gcc doesn't define __BIG_ENDIAN__)
    202 #if !defined(WORDS_BIGENDIAN) && \
    203     (defined(__BIG_ENDIAN__) || defined(_M_PPC) || \
    204      (defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)))
    205 #define WORDS_BIGENDIAN
    206 #endif
    207 
    208 typedef enum {
    209   kSSE2,
    210   kSSE3,
    211   kSlowSSSE3,  // special feature for slow SSSE3 architectures
    212   kSSE4_1,
    213   kAVX,
    214   kAVX2,
    215   kNEON,
    216   kMIPS32,
    217   kMIPSdspR2,
    218   kMSA
    219 } CPUFeature;
    220 // returns true if the CPU supports the feature.
    221 typedef int (*VP8CPUInfo)(CPUFeature feature);
    222 WEBP_EXTERN VP8CPUInfo VP8GetCPUInfo;
    223 
    224 //------------------------------------------------------------------------------
    225 // Init stub generator
    226 
    227 // Defines an init function stub to ensure each module exposes a symbol,
    228 // avoiding a compiler warning.
    229 #define WEBP_DSP_INIT_STUB(func) \
    230   extern void func(void); \
    231   void func(void) {}
    232 
    233 //------------------------------------------------------------------------------
    234 // Encoding
    235 
    236 // Transforms
    237 // VP8Idct: Does one of two inverse transforms. If do_two is set, the transforms
    238 //          will be done for (ref, in, dst) and (ref + 4, in + 16, dst + 4).
    239 typedef void (*VP8Idct)(const uint8_t* ref, const int16_t* in, uint8_t* dst,
    240                         int do_two);
    241 typedef void (*VP8Fdct)(const uint8_t* src, const uint8_t* ref, int16_t* out);
    242 typedef void (*VP8WHT)(const int16_t* in, int16_t* out);
    243 extern VP8Idct VP8ITransform;
    244 extern VP8Fdct VP8FTransform;
    245 extern VP8Fdct VP8FTransform2;   // performs two transforms at a time
    246 extern VP8WHT VP8FTransformWHT;
    247 // Predictions
    248 // *dst is the destination block. *top and *left can be NULL.
    249 typedef void (*VP8IntraPreds)(uint8_t *dst, const uint8_t* left,
    250                               const uint8_t* top);
    251 typedef void (*VP8Intra4Preds)(uint8_t *dst, const uint8_t* top);
    252 extern VP8Intra4Preds VP8EncPredLuma4;
    253 extern VP8IntraPreds VP8EncPredLuma16;
    254 extern VP8IntraPreds VP8EncPredChroma8;
    255 
    256 typedef int (*VP8Metric)(const uint8_t* pix, const uint8_t* ref);
    257 extern VP8Metric VP8SSE16x16, VP8SSE16x8, VP8SSE8x8, VP8SSE4x4;
    258 typedef int (*VP8WMetric)(const uint8_t* pix, const uint8_t* ref,
    259                           const uint16_t* const weights);
    260 // The weights for VP8TDisto4x4 and VP8TDisto16x16 contain a row-major
    261 // 4 by 4 symmetric matrix.
    262 extern VP8WMetric VP8TDisto4x4, VP8TDisto16x16;
    263 
    264 // Compute the average (DC) of four 4x4 blocks.
    265 // Each sub-4x4 block #i sum is stored in dc[i].
    266 typedef void (*VP8MeanMetric)(const uint8_t* ref, uint32_t dc[4]);
    267 extern VP8MeanMetric VP8Mean16x4;
    268 
    269 typedef void (*VP8BlockCopy)(const uint8_t* src, uint8_t* dst);
    270 extern VP8BlockCopy VP8Copy4x4;
    271 extern VP8BlockCopy VP8Copy16x8;
    272 // Quantization
    273 struct VP8Matrix;   // forward declaration
    274 typedef int (*VP8QuantizeBlock)(int16_t in[16], int16_t out[16],
    275                                 const struct VP8Matrix* const mtx);
    276 // Same as VP8QuantizeBlock, but quantizes two consecutive blocks.
    277 typedef int (*VP8Quantize2Blocks)(int16_t in[32], int16_t out[32],
    278                                   const struct VP8Matrix* const mtx);
    279 
    280 extern VP8QuantizeBlock VP8EncQuantizeBlock;
    281 extern VP8Quantize2Blocks VP8EncQuantize2Blocks;
    282 
    283 // specific to 2nd transform:
    284 typedef int (*VP8QuantizeBlockWHT)(int16_t in[16], int16_t out[16],
    285                                    const struct VP8Matrix* const mtx);
    286 extern VP8QuantizeBlockWHT VP8EncQuantizeBlockWHT;
    287 
    288 extern const int VP8DspScan[16 + 4 + 4];
    289 
    290 // Collect histogram for susceptibility calculation.
    291 #define MAX_COEFF_THRESH   31   // size of histogram used by CollectHistogram.
    292 typedef struct {
    293   // We only need to store max_value and last_non_zero, not the distribution.
    294   int max_value;
    295   int last_non_zero;
    296 } VP8Histogram;
    297 typedef void (*VP8CHisto)(const uint8_t* ref, const uint8_t* pred,
    298                           int start_block, int end_block,
    299                           VP8Histogram* const histo);
    300 extern VP8CHisto VP8CollectHistogram;
    301 // General-purpose util function to help VP8CollectHistogram().
    302 void VP8SetHistogramData(const int distribution[MAX_COEFF_THRESH + 1],
    303                          VP8Histogram* const histo);
    304 
    305 // must be called before using any of the above
    306 void VP8EncDspInit(void);
    307 
    308 //------------------------------------------------------------------------------
    309 // cost functions (encoding)
    310 
    311 extern const uint16_t VP8EntropyCost[256];        // 8bit fixed-point log(p)
    312 // approximate cost per level:
    313 extern const uint16_t VP8LevelFixedCosts[2047 /*MAX_LEVEL*/ + 1];
    314 extern const uint8_t VP8EncBands[16 + 1];
    315 
    316 struct VP8Residual;
    317 typedef void (*VP8SetResidualCoeffsFunc)(const int16_t* const coeffs,
    318                                          struct VP8Residual* const res);
    319 extern VP8SetResidualCoeffsFunc VP8SetResidualCoeffs;
    320 
    321 // Cost calculation function.
    322 typedef int (*VP8GetResidualCostFunc)(int ctx0,
    323                                       const struct VP8Residual* const res);
    324 extern VP8GetResidualCostFunc VP8GetResidualCost;
    325 
    326 // must be called before anything using the above
    327 void VP8EncDspCostInit(void);
    328 
    329 //------------------------------------------------------------------------------
    330 // SSIM / PSNR utils
    331 
    332 // struct for accumulating statistical moments
    333 typedef struct {
    334   uint32_t w;              // sum(w_i) : sum of weights
    335   uint32_t xm, ym;         // sum(w_i * x_i), sum(w_i * y_i)
    336   uint32_t xxm, xym, yym;  // sum(w_i * x_i * x_i), etc.
    337 } VP8DistoStats;
    338 
    339 // Compute the final SSIM value
    340 // The non-clipped version assumes stats->w = (2 * VP8_SSIM_KERNEL + 1)^2.
    341 double VP8SSIMFromStats(const VP8DistoStats* const stats);
    342 double VP8SSIMFromStatsClipped(const VP8DistoStats* const stats);
    343 
    344 #define VP8_SSIM_KERNEL 3   // total size of the kernel: 2 * VP8_SSIM_KERNEL + 1
    345 typedef double (*VP8SSIMGetClippedFunc)(const uint8_t* src1, int stride1,
    346                                         const uint8_t* src2, int stride2,
    347                                         int xo, int yo,  // center position
    348                                         int W, int H);   // plane dimension
    349 
    350 #if !defined(WEBP_REDUCE_SIZE)
    351 // This version is called with the guarantee that you can load 8 bytes and
    352 // 8 rows at offset src1 and src2
    353 typedef double (*VP8SSIMGetFunc)(const uint8_t* src1, int stride1,
    354                                  const uint8_t* src2, int stride2);
    355 
    356 extern VP8SSIMGetFunc VP8SSIMGet;         // unclipped / unchecked
    357 extern VP8SSIMGetClippedFunc VP8SSIMGetClipped;   // with clipping
    358 #endif
    359 
    360 #if !defined(WEBP_DISABLE_STATS)
    361 typedef uint32_t (*VP8AccumulateSSEFunc)(const uint8_t* src1,
    362                                          const uint8_t* src2, int len);
    363 extern VP8AccumulateSSEFunc VP8AccumulateSSE;
    364 #endif
    365 
    366 // must be called before using any of the above directly
    367 void VP8SSIMDspInit(void);
    368 
    369 //------------------------------------------------------------------------------
    370 // Decoding
    371 
    372 typedef void (*VP8DecIdct)(const int16_t* coeffs, uint8_t* dst);
    373 // when doing two transforms, coeffs is actually int16_t[2][16].
    374 typedef void (*VP8DecIdct2)(const int16_t* coeffs, uint8_t* dst, int do_two);
    375 extern VP8DecIdct2 VP8Transform;
    376 extern VP8DecIdct VP8TransformAC3;
    377 extern VP8DecIdct VP8TransformUV;
    378 extern VP8DecIdct VP8TransformDC;
    379 extern VP8DecIdct VP8TransformDCUV;
    380 extern VP8WHT VP8TransformWHT;
    381 
    382 // *dst is the destination block, with stride BPS. Boundary samples are
    383 // assumed accessible when needed.
    384 typedef void (*VP8PredFunc)(uint8_t* dst);
    385 extern VP8PredFunc VP8PredLuma16[/* NUM_B_DC_MODES */];
    386 extern VP8PredFunc VP8PredChroma8[/* NUM_B_DC_MODES */];
    387 extern VP8PredFunc VP8PredLuma4[/* NUM_BMODES */];
    388 
    389 // clipping tables (for filtering)
    390 extern const int8_t* const VP8ksclip1;  // clips [-1020, 1020] to [-128, 127]
    391 extern const int8_t* const VP8ksclip2;  // clips [-112, 112] to [-16, 15]
    392 extern const uint8_t* const VP8kclip1;  // clips [-255,511] to [0,255]
    393 extern const uint8_t* const VP8kabs0;   // abs(x) for x in [-255,255]
    394 // must be called first
    395 void VP8InitClipTables(void);
    396 
    397 // simple filter (only for luma)
    398 typedef void (*VP8SimpleFilterFunc)(uint8_t* p, int stride, int thresh);
    399 extern VP8SimpleFilterFunc VP8SimpleVFilter16;
    400 extern VP8SimpleFilterFunc VP8SimpleHFilter16;
    401 extern VP8SimpleFilterFunc VP8SimpleVFilter16i;  // filter 3 inner edges
    402 extern VP8SimpleFilterFunc VP8SimpleHFilter16i;
    403 
    404 // regular filter (on both macroblock edges and inner edges)
    405 typedef void (*VP8LumaFilterFunc)(uint8_t* luma, int stride,
    406                                   int thresh, int ithresh, int hev_t);
    407 typedef void (*VP8ChromaFilterFunc)(uint8_t* u, uint8_t* v, int stride,
    408                                     int thresh, int ithresh, int hev_t);
    409 // on outer edge
    410 extern VP8LumaFilterFunc VP8VFilter16;
    411 extern VP8LumaFilterFunc VP8HFilter16;
    412 extern VP8ChromaFilterFunc VP8VFilter8;
    413 extern VP8ChromaFilterFunc VP8HFilter8;
    414 
    415 // on inner edge
    416 extern VP8LumaFilterFunc VP8VFilter16i;   // filtering 3 inner edges altogether
    417 extern VP8LumaFilterFunc VP8HFilter16i;
    418 extern VP8ChromaFilterFunc VP8VFilter8i;  // filtering u and v altogether
    419 extern VP8ChromaFilterFunc VP8HFilter8i;
    420 
    421 // Dithering. Combines dithering values (centered around 128) with dst[],
    422 // according to: dst[] = clip(dst[] + (((dither[]-128) + 8) >> 4)
    423 #define VP8_DITHER_DESCALE 4
    424 #define VP8_DITHER_DESCALE_ROUNDER (1 << (VP8_DITHER_DESCALE - 1))
    425 #define VP8_DITHER_AMP_BITS 7
    426 #define VP8_DITHER_AMP_CENTER (1 << VP8_DITHER_AMP_BITS)
    427 extern void (*VP8DitherCombine8x8)(const uint8_t* dither, uint8_t* dst,
    428                                    int dst_stride);
    429 
    430 // must be called before anything using the above
    431 void VP8DspInit(void);
    432 
    433 //------------------------------------------------------------------------------
    434 // WebP I/O
    435 
    436 #define FANCY_UPSAMPLING   // undefined to remove fancy upsampling support
    437 
    438 // Convert a pair of y/u/v lines together to the output rgb/a colorspace.
    439 // bottom_y can be NULL if only one line of output is needed (at top/bottom).
    440 typedef void (*WebPUpsampleLinePairFunc)(
    441     const uint8_t* top_y, const uint8_t* bottom_y,
    442     const uint8_t* top_u, const uint8_t* top_v,
    443     const uint8_t* cur_u, const uint8_t* cur_v,
    444     uint8_t* top_dst, uint8_t* bottom_dst, int len);
    445 
    446 #ifdef FANCY_UPSAMPLING
    447 
    448 // Fancy upsampling functions to convert YUV to RGB(A) modes
    449 extern WebPUpsampleLinePairFunc WebPUpsamplers[/* MODE_LAST */];
    450 
    451 #endif    // FANCY_UPSAMPLING
    452 
    453 // Per-row point-sampling methods.
    454 typedef void (*WebPSamplerRowFunc)(const uint8_t* y,
    455                                    const uint8_t* u, const uint8_t* v,
    456                                    uint8_t* dst, int len);
    457 // Generic function to apply 'WebPSamplerRowFunc' to the whole plane:
    458 void WebPSamplerProcessPlane(const uint8_t* y, int y_stride,
    459                              const uint8_t* u, const uint8_t* v, int uv_stride,
    460                              uint8_t* dst, int dst_stride,
    461                              int width, int height, WebPSamplerRowFunc func);
    462 
    463 // Sampling functions to convert rows of YUV to RGB(A)
    464 extern WebPSamplerRowFunc WebPSamplers[/* MODE_LAST */];
    465 
    466 // General function for converting two lines of ARGB or RGBA.
    467 // 'alpha_is_last' should be true if 0xff000000 is stored in memory as
    468 // as 0x00, 0x00, 0x00, 0xff (little endian).
    469 WebPUpsampleLinePairFunc WebPGetLinePairConverter(int alpha_is_last);
    470 
    471 // YUV444->RGB converters
    472 typedef void (*WebPYUV444Converter)(const uint8_t* y,
    473                                     const uint8_t* u, const uint8_t* v,
    474                                     uint8_t* dst, int len);
    475 
    476 extern WebPYUV444Converter WebPYUV444Converters[/* MODE_LAST */];
    477 
    478 // Must be called before using the WebPUpsamplers[] (and for premultiplied
    479 // colorspaces like rgbA, rgbA4444, etc)
    480 void WebPInitUpsamplers(void);
    481 // Must be called before using WebPSamplers[]
    482 void WebPInitSamplers(void);
    483 // Must be called before using WebPYUV444Converters[]
    484 void WebPInitYUV444Converters(void);
    485 
    486 //------------------------------------------------------------------------------
    487 // ARGB -> YUV converters
    488 
    489 // Convert ARGB samples to luma Y.
    490 extern void (*WebPConvertARGBToY)(const uint32_t* argb, uint8_t* y, int width);
    491 // Convert ARGB samples to U/V with downsampling. do_store should be '1' for
    492 // even lines and '0' for odd ones. 'src_width' is the original width, not
    493 // the U/V one.
    494 extern void (*WebPConvertARGBToUV)(const uint32_t* argb, uint8_t* u, uint8_t* v,
    495                                    int src_width, int do_store);
    496 
    497 // Convert a row of accumulated (four-values) of rgba32 toward U/V
    498 extern void (*WebPConvertRGBA32ToUV)(const uint16_t* rgb,
    499                                      uint8_t* u, uint8_t* v, int width);
    500 
    501 // Convert RGB or BGR to Y
    502 extern void (*WebPConvertRGB24ToY)(const uint8_t* rgb, uint8_t* y, int width);
    503 extern void (*WebPConvertBGR24ToY)(const uint8_t* bgr, uint8_t* y, int width);
    504 
    505 // used for plain-C fallback.
    506 extern void WebPConvertARGBToUV_C(const uint32_t* argb, uint8_t* u, uint8_t* v,
    507                                   int src_width, int do_store);
    508 extern void WebPConvertRGBA32ToUV_C(const uint16_t* rgb,
    509                                     uint8_t* u, uint8_t* v, int width);
    510 
    511 // utilities for accurate RGB->YUV conversion
    512 extern uint64_t (*WebPSharpYUVUpdateY)(const uint16_t* src, const uint16_t* ref,
    513                                        uint16_t* dst, int len);
    514 extern void (*WebPSharpYUVUpdateRGB)(const int16_t* src, const int16_t* ref,
    515                                      int16_t* dst, int len);
    516 extern void (*WebPSharpYUVFilterRow)(const int16_t* A, const int16_t* B,
    517                                      int len,
    518                                      const uint16_t* best_y, uint16_t* out);
    519 
    520 // Must be called before using the above.
    521 void WebPInitConvertARGBToYUV(void);
    522 
    523 //------------------------------------------------------------------------------
    524 // Rescaler
    525 
    526 struct WebPRescaler;
    527 
    528 // Import a row of data and save its contribution in the rescaler.
    529 // 'channel' denotes the channel number to be imported. 'Expand' corresponds to
    530 // the wrk->x_expand case. Otherwise, 'Shrink' is to be used.
    531 typedef void (*WebPRescalerImportRowFunc)(struct WebPRescaler* const wrk,
    532                                           const uint8_t* src);
    533 
    534 extern WebPRescalerImportRowFunc WebPRescalerImportRowExpand;
    535 extern WebPRescalerImportRowFunc WebPRescalerImportRowShrink;
    536 
    537 // Export one row (starting at x_out position) from rescaler.
    538 // 'Expand' corresponds to the wrk->y_expand case.
    539 // Otherwise 'Shrink' is to be used
    540 typedef void (*WebPRescalerExportRowFunc)(struct WebPRescaler* const wrk);
    541 extern WebPRescalerExportRowFunc WebPRescalerExportRowExpand;
    542 extern WebPRescalerExportRowFunc WebPRescalerExportRowShrink;
    543 
    544 // Plain-C implementation, as fall-back.
    545 extern void WebPRescalerImportRowExpand_C(struct WebPRescaler* const wrk,
    546                                           const uint8_t* src);
    547 extern void WebPRescalerImportRowShrink_C(struct WebPRescaler* const wrk,
    548                                           const uint8_t* src);
    549 extern void WebPRescalerExportRowExpand_C(struct WebPRescaler* const wrk);
    550 extern void WebPRescalerExportRowShrink_C(struct WebPRescaler* const wrk);
    551 
    552 // Main entry calls:
    553 extern void WebPRescalerImportRow(struct WebPRescaler* const wrk,
    554                                   const uint8_t* src);
    555 // Export one row (starting at x_out position) from rescaler.
    556 extern void WebPRescalerExportRow(struct WebPRescaler* const wrk);
    557 
    558 // Must be called first before using the above.
    559 void WebPRescalerDspInit(void);
    560 
    561 //------------------------------------------------------------------------------
    562 // Utilities for processing transparent channel.
    563 
    564 // Apply alpha pre-multiply on an rgba, bgra or argb plane of size w * h.
    565 // alpha_first should be 0 for argb, 1 for rgba or bgra (where alpha is last).
    566 extern void (*WebPApplyAlphaMultiply)(
    567     uint8_t* rgba, int alpha_first, int w, int h, int stride);
    568 
    569 // Same, buf specifically for RGBA4444 format
    570 extern void (*WebPApplyAlphaMultiply4444)(
    571     uint8_t* rgba4444, int w, int h, int stride);
    572 
    573 // Dispatch the values from alpha[] plane to the ARGB destination 'dst'.
    574 // Returns true if alpha[] plane has non-trivial values different from 0xff.
    575 extern int (*WebPDispatchAlpha)(const uint8_t* alpha, int alpha_stride,
    576                                 int width, int height,
    577                                 uint8_t* dst, int dst_stride);
    578 
    579 // Transfer packed 8b alpha[] values to green channel in dst[], zero'ing the
    580 // A/R/B values. 'dst_stride' is the stride for dst[] in uint32_t units.
    581 extern void (*WebPDispatchAlphaToGreen)(const uint8_t* alpha, int alpha_stride,
    582                                         int width, int height,
    583                                         uint32_t* dst, int dst_stride);
    584 
    585 // Extract the alpha values from 32b values in argb[] and pack them into alpha[]
    586 // (this is the opposite of WebPDispatchAlpha).
    587 // Returns true if there's only trivial 0xff alpha values.
    588 extern int (*WebPExtractAlpha)(const uint8_t* argb, int argb_stride,
    589                                int width, int height,
    590                                uint8_t* alpha, int alpha_stride);
    591 
    592 // Extract the green values from 32b values in argb[] and pack them into alpha[]
    593 // (this is the opposite of WebPDispatchAlphaToGreen).
    594 extern void (*WebPExtractGreen)(const uint32_t* argb, uint8_t* alpha, int size);
    595 
    596 // Pre-Multiply operation transforms x into x * A / 255  (where x=Y,R,G or B).
    597 // Un-Multiply operation transforms x into x * 255 / A.
    598 
    599 // Pre-Multiply or Un-Multiply (if 'inverse' is true) argb values in a row.
    600 extern void (*WebPMultARGBRow)(uint32_t* const ptr, int width, int inverse);
    601 
    602 // Same a WebPMultARGBRow(), but for several rows.
    603 void WebPMultARGBRows(uint8_t* ptr, int stride, int width, int num_rows,
    604                       int inverse);
    605 
    606 // Same for a row of single values, with side alpha values.
    607 extern void (*WebPMultRow)(uint8_t* const ptr, const uint8_t* const alpha,
    608                            int width, int inverse);
    609 
    610 // Same a WebPMultRow(), but for several 'num_rows' rows.
    611 void WebPMultRows(uint8_t* ptr, int stride,
    612                   const uint8_t* alpha, int alpha_stride,
    613                   int width, int num_rows, int inverse);
    614 
    615 // Plain-C versions, used as fallback by some implementations.
    616 void WebPMultRow_C(uint8_t* const ptr, const uint8_t* const alpha,
    617                    int width, int inverse);
    618 void WebPMultARGBRow_C(uint32_t* const ptr, int width, int inverse);
    619 
    620 #ifdef WORDS_BIGENDIAN
    621 // ARGB packing function: a/r/g/b input is rgba or bgra order.
    622 extern void (*WebPPackARGB)(const uint8_t* a, const uint8_t* r,
    623                             const uint8_t* g, const uint8_t* b, int len,
    624                             uint32_t* out);
    625 #endif
    626 
    627 // RGB packing function. 'step' can be 3 or 4. r/g/b input is rgb or bgr order.
    628 extern void (*WebPPackRGB)(const uint8_t* r, const uint8_t* g, const uint8_t* b,
    629                            int len, int step, uint32_t* out);
    630 
    631 // This function returns true if src[i] contains a value different from 0xff.
    632 extern int (*WebPHasAlpha8b)(const uint8_t* src, int length);
    633 // This function returns true if src[4*i] contains a value different from 0xff.
    634 extern int (*WebPHasAlpha32b)(const uint8_t* src, int length);
    635 
    636 // To be called first before using the above.
    637 void WebPInitAlphaProcessing(void);
    638 
    639 //------------------------------------------------------------------------------
    640 // Filter functions
    641 
    642 typedef enum {     // Filter types.
    643   WEBP_FILTER_NONE = 0,
    644   WEBP_FILTER_HORIZONTAL,
    645   WEBP_FILTER_VERTICAL,
    646   WEBP_FILTER_GRADIENT,
    647   WEBP_FILTER_LAST = WEBP_FILTER_GRADIENT + 1,  // end marker
    648   WEBP_FILTER_BEST,    // meta-types
    649   WEBP_FILTER_FAST
    650 } WEBP_FILTER_TYPE;
    651 
    652 typedef void (*WebPFilterFunc)(const uint8_t* in, int width, int height,
    653                                int stride, uint8_t* out);
    654 // In-place un-filtering.
    655 // Warning! 'prev_line' pointer can be equal to 'cur_line' or 'preds'.
    656 typedef void (*WebPUnfilterFunc)(const uint8_t* prev_line, const uint8_t* preds,
    657                                  uint8_t* cur_line, int width);
    658 
    659 // Filter the given data using the given predictor.
    660 // 'in' corresponds to a 2-dimensional pixel array of size (stride * height)
    661 // in raster order.
    662 // 'stride' is number of bytes per scan line (with possible padding).
    663 // 'out' should be pre-allocated.
    664 extern WebPFilterFunc WebPFilters[WEBP_FILTER_LAST];
    665 
    666 // In-place reconstruct the original data from the given filtered data.
    667 // The reconstruction will be done for 'num_rows' rows starting from 'row'
    668 // (assuming rows upto 'row - 1' are already reconstructed).
    669 extern WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST];
    670 
    671 // To be called first before using the above.
    672 void VP8FiltersInit(void);
    673 
    674 #ifdef __cplusplus
    675 }    // extern "C"
    676 #endif
    677 
    678 #endif  // WEBP_DSP_DSP_H_
    679