Home | History | Annotate | Download | only in dsp
      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 "../webp/config.h"
     19 #endif
     20 
     21 #include "../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 #ifndef __has_builtin
     42 # define __has_builtin(x) 0
     43 #endif
     44 
     45 #if defined(_MSC_VER) && _MSC_VER > 1310 && \
     46     (defined(_M_X64) || defined(_M_IX86))
     47 #define WEBP_MSC_SSE2  // Visual C++ SSE2 targets
     48 #endif
     49 
     50 #if defined(_MSC_VER) && _MSC_VER >= 1500 && \
     51     (defined(_M_X64) || defined(_M_IX86))
     52 #define WEBP_MSC_SSE41  // Visual C++ SSE4.1 targets
     53 #endif
     54 
     55 // WEBP_HAVE_* are used to indicate the presence of the instruction set in dsp
     56 // files without intrinsics, allowing the corresponding Init() to be called.
     57 // Files containing intrinsics will need to be built targeting the instruction
     58 // set so should succeed on one of the earlier tests.
     59 #if defined(__SSE2__) || defined(WEBP_MSC_SSE2) || defined(WEBP_HAVE_SSE2)
     60 #define WEBP_USE_SSE2
     61 #endif
     62 
     63 #if defined(__SSE4_1__) || defined(WEBP_MSC_SSE41) || defined(WEBP_HAVE_SSE41)
     64 #define WEBP_USE_SSE41
     65 #endif
     66 
     67 #if defined(__AVX2__) || defined(WEBP_HAVE_AVX2)
     68 #define WEBP_USE_AVX2
     69 #endif
     70 
     71 // The intrinsics currently cause compiler errors with arm-nacl-gcc and the
     72 // inline assembly would need to be modified for use with Native Client.
     73 #if (defined(__ARM_NEON__) || \
     74      defined(__aarch64__) || defined(WEBP_HAVE_NEON)) && \
     75     !defined(__native_client__)
     76 #define WEBP_USE_NEON
     77 #endif
     78 
     79 #if defined(_MSC_VER) && _MSC_VER >= 1700 && defined(_M_ARM)
     80 #define WEBP_USE_NEON
     81 #define WEBP_USE_INTRINSICS
     82 #endif
     83 
     84 #if defined(__mips__) && !defined(__mips64) && \
     85     defined(__mips_isa_rev) && (__mips_isa_rev >= 1) && (__mips_isa_rev < 6)
     86 #define WEBP_USE_MIPS32
     87 #if (__mips_isa_rev >= 2)
     88 #define WEBP_USE_MIPS32_R2
     89 #if defined(__mips_dspr2) || (__mips_dsp_rev >= 2)
     90 #define WEBP_USE_MIPS_DSP_R2
     91 #endif
     92 #endif
     93 #endif
     94 
     95 #if defined(__mips_msa) && defined(__mips_isa_rev) && (__mips_isa_rev >= 5)
     96 #define WEBP_USE_MSA
     97 #endif
     98 
     99 // This macro prevents thread_sanitizer from reporting known concurrent writes.
    100 #define WEBP_TSAN_IGNORE_FUNCTION
    101 #if defined(__has_feature)
    102 #if __has_feature(thread_sanitizer)
    103 #undef WEBP_TSAN_IGNORE_FUNCTION
    104 #define WEBP_TSAN_IGNORE_FUNCTION __attribute__((no_sanitize_thread))
    105 #endif
    106 #endif
    107 
    108 #define WEBP_UBSAN_IGNORE_UNDEF
    109 #define WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW
    110 #if defined(__clang__) && defined(__has_attribute)
    111 #if __has_attribute(no_sanitize)
    112 // This macro prevents the undefined behavior sanitizer from reporting
    113 // failures. This is only meant to silence unaligned loads on platforms that
    114 // are known to support them.
    115 #undef WEBP_UBSAN_IGNORE_UNDEF
    116 #define WEBP_UBSAN_IGNORE_UNDEF \
    117   __attribute__((no_sanitize("undefined")))
    118 
    119 // This macro prevents the undefined behavior sanitizer from reporting
    120 // failures related to unsigned integer overflows. This is only meant to
    121 // silence cases where this well defined behavior is expected.
    122 #undef WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW
    123 #define WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW \
    124   __attribute__((no_sanitize("unsigned-integer-overflow")))
    125 #endif
    126 #endif
    127 
    128 typedef enum {
    129   kSSE2,
    130   kSSE3,
    131   kSlowSSSE3,  // special feature for slow SSSE3 architectures
    132   kSSE4_1,
    133   kAVX,
    134   kAVX2,
    135   kNEON,
    136   kMIPS32,
    137   kMIPSdspR2,
    138   kMSA
    139 } CPUFeature;
    140 // returns true if the CPU supports the feature.
    141 typedef int (*VP8CPUInfo)(CPUFeature feature);
    142 WEBP_EXTERN(VP8CPUInfo) VP8GetCPUInfo;
    143 
    144 //------------------------------------------------------------------------------
    145 // Init stub generator
    146 
    147 // Defines an init function stub to ensure each module exposes a symbol,
    148 // avoiding a compiler warning.
    149 #define WEBP_DSP_INIT_STUB(func) \
    150   extern void func(void); \
    151   WEBP_TSAN_IGNORE_FUNCTION void func(void) {}
    152 
    153 //------------------------------------------------------------------------------
    154 // Encoding
    155 
    156 // Transforms
    157 // VP8Idct: Does one of two inverse transforms. If do_two is set, the transforms
    158 //          will be done for (ref, in, dst) and (ref + 4, in + 16, dst + 4).
    159 typedef void (*VP8Idct)(const uint8_t* ref, const int16_t* in, uint8_t* dst,
    160                         int do_two);
    161 typedef void (*VP8Fdct)(const uint8_t* src, const uint8_t* ref, int16_t* out);
    162 typedef void (*VP8WHT)(const int16_t* in, int16_t* out);
    163 extern VP8Idct VP8ITransform;
    164 extern VP8Fdct VP8FTransform;
    165 extern VP8Fdct VP8FTransform2;   // performs two transforms at a time
    166 extern VP8WHT VP8FTransformWHT;
    167 // Predictions
    168 // *dst is the destination block. *top and *left can be NULL.
    169 typedef void (*VP8IntraPreds)(uint8_t *dst, const uint8_t* left,
    170                               const uint8_t* top);
    171 typedef void (*VP8Intra4Preds)(uint8_t *dst, const uint8_t* top);
    172 extern VP8Intra4Preds VP8EncPredLuma4;
    173 extern VP8IntraPreds VP8EncPredLuma16;
    174 extern VP8IntraPreds VP8EncPredChroma8;
    175 
    176 typedef int (*VP8Metric)(const uint8_t* pix, const uint8_t* ref);
    177 extern VP8Metric VP8SSE16x16, VP8SSE16x8, VP8SSE8x8, VP8SSE4x4;
    178 typedef int (*VP8WMetric)(const uint8_t* pix, const uint8_t* ref,
    179                           const uint16_t* const weights);
    180 // The weights for VP8TDisto4x4 and VP8TDisto16x16 contain a row-major
    181 // 4 by 4 symmetric matrix.
    182 extern VP8WMetric VP8TDisto4x4, VP8TDisto16x16;
    183 
    184 // Compute the average (DC) of four 4x4 blocks.
    185 // Each sub-4x4 block #i sum is stored in dc[i].
    186 typedef void (*VP8MeanMetric)(const uint8_t* ref, uint32_t dc[4]);
    187 extern VP8MeanMetric VP8Mean16x4;
    188 
    189 typedef void (*VP8BlockCopy)(const uint8_t* src, uint8_t* dst);
    190 extern VP8BlockCopy VP8Copy4x4;
    191 extern VP8BlockCopy VP8Copy16x8;
    192 // Quantization
    193 struct VP8Matrix;   // forward declaration
    194 typedef int (*VP8QuantizeBlock)(int16_t in[16], int16_t out[16],
    195                                 const struct VP8Matrix* const mtx);
    196 // Same as VP8QuantizeBlock, but quantizes two consecutive blocks.
    197 typedef int (*VP8Quantize2Blocks)(int16_t in[32], int16_t out[32],
    198                                   const struct VP8Matrix* const mtx);
    199 
    200 extern VP8QuantizeBlock VP8EncQuantizeBlock;
    201 extern VP8Quantize2Blocks VP8EncQuantize2Blocks;
    202 
    203 // specific to 2nd transform:
    204 typedef int (*VP8QuantizeBlockWHT)(int16_t in[16], int16_t out[16],
    205                                    const struct VP8Matrix* const mtx);
    206 extern VP8QuantizeBlockWHT VP8EncQuantizeBlockWHT;
    207 
    208 extern const int VP8DspScan[16 + 4 + 4];
    209 
    210 // Collect histogram for susceptibility calculation.
    211 #define MAX_COEFF_THRESH   31   // size of histogram used by CollectHistogram.
    212 typedef struct {
    213   // We only need to store max_value and last_non_zero, not the distribution.
    214   int max_value;
    215   int last_non_zero;
    216 } VP8Histogram;
    217 typedef void (*VP8CHisto)(const uint8_t* ref, const uint8_t* pred,
    218                           int start_block, int end_block,
    219                           VP8Histogram* const histo);
    220 extern VP8CHisto VP8CollectHistogram;
    221 // General-purpose util function to help VP8CollectHistogram().
    222 void VP8SetHistogramData(const int distribution[MAX_COEFF_THRESH + 1],
    223                          VP8Histogram* const histo);
    224 
    225 // must be called before using any of the above
    226 void VP8EncDspInit(void);
    227 
    228 //------------------------------------------------------------------------------
    229 // cost functions (encoding)
    230 
    231 extern const uint16_t VP8EntropyCost[256];        // 8bit fixed-point log(p)
    232 // approximate cost per level:
    233 extern const uint16_t VP8LevelFixedCosts[2047 /*MAX_LEVEL*/ + 1];
    234 extern const uint8_t VP8EncBands[16 + 1];
    235 
    236 struct VP8Residual;
    237 typedef void (*VP8SetResidualCoeffsFunc)(const int16_t* const coeffs,
    238                                          struct VP8Residual* const res);
    239 extern VP8SetResidualCoeffsFunc VP8SetResidualCoeffs;
    240 
    241 // Cost calculation function.
    242 typedef int (*VP8GetResidualCostFunc)(int ctx0,
    243                                       const struct VP8Residual* const res);
    244 extern VP8GetResidualCostFunc VP8GetResidualCost;
    245 
    246 // must be called before anything using the above
    247 void VP8EncDspCostInit(void);
    248 
    249 //------------------------------------------------------------------------------
    250 // SSIM / PSNR utils
    251 
    252 // struct for accumulating statistical moments
    253 typedef struct {
    254   uint32_t w;              // sum(w_i) : sum of weights
    255   uint32_t xm, ym;         // sum(w_i * x_i), sum(w_i * y_i)
    256   uint32_t xxm, xym, yym;  // sum(w_i * x_i * x_i), etc.
    257 } VP8DistoStats;
    258 
    259 // Compute the final SSIM value
    260 // The non-clipped version assumes stats->w = (2 * VP8_SSIM_KERNEL + 1)^2.
    261 double VP8SSIMFromStats(const VP8DistoStats* const stats);
    262 double VP8SSIMFromStatsClipped(const VP8DistoStats* const stats);
    263 
    264 #define VP8_SSIM_KERNEL 3   // total size of the kernel: 2 * VP8_SSIM_KERNEL + 1
    265 typedef double (*VP8SSIMGetClippedFunc)(const uint8_t* src1, int stride1,
    266                                         const uint8_t* src2, int stride2,
    267                                         int xo, int yo,  // center position
    268                                         int W, int H);   // plane dimension
    269 
    270 // This version is called with the guarantee that you can load 8 bytes and
    271 // 8 rows at offset src1 and src2
    272 typedef double (*VP8SSIMGetFunc)(const uint8_t* src1, int stride1,
    273                                  const uint8_t* src2, int stride2);
    274 
    275 extern VP8SSIMGetFunc VP8SSIMGet;         // unclipped / unchecked
    276 extern VP8SSIMGetClippedFunc VP8SSIMGetClipped;   // with clipping
    277 
    278 typedef uint32_t (*VP8AccumulateSSEFunc)(const uint8_t* src1,
    279                                          const uint8_t* src2, int len);
    280 extern VP8AccumulateSSEFunc VP8AccumulateSSE;
    281 
    282 // must be called before using any of the above directly
    283 void VP8SSIMDspInit(void);
    284 
    285 //------------------------------------------------------------------------------
    286 // Decoding
    287 
    288 typedef void (*VP8DecIdct)(const int16_t* coeffs, uint8_t* dst);
    289 // when doing two transforms, coeffs is actually int16_t[2][16].
    290 typedef void (*VP8DecIdct2)(const int16_t* coeffs, uint8_t* dst, int do_two);
    291 extern VP8DecIdct2 VP8Transform;
    292 extern VP8DecIdct VP8TransformAC3;
    293 extern VP8DecIdct VP8TransformUV;
    294 extern VP8DecIdct VP8TransformDC;
    295 extern VP8DecIdct VP8TransformDCUV;
    296 extern VP8WHT VP8TransformWHT;
    297 
    298 // *dst is the destination block, with stride BPS. Boundary samples are
    299 // assumed accessible when needed.
    300 typedef void (*VP8PredFunc)(uint8_t* dst);
    301 extern VP8PredFunc VP8PredLuma16[/* NUM_B_DC_MODES */];
    302 extern VP8PredFunc VP8PredChroma8[/* NUM_B_DC_MODES */];
    303 extern VP8PredFunc VP8PredLuma4[/* NUM_BMODES */];
    304 
    305 // clipping tables (for filtering)
    306 extern const int8_t* const VP8ksclip1;  // clips [-1020, 1020] to [-128, 127]
    307 extern const int8_t* const VP8ksclip2;  // clips [-112, 112] to [-16, 15]
    308 extern const uint8_t* const VP8kclip1;  // clips [-255,511] to [0,255]
    309 extern const uint8_t* const VP8kabs0;   // abs(x) for x in [-255,255]
    310 // must be called first
    311 void VP8InitClipTables(void);
    312 
    313 // simple filter (only for luma)
    314 typedef void (*VP8SimpleFilterFunc)(uint8_t* p, int stride, int thresh);
    315 extern VP8SimpleFilterFunc VP8SimpleVFilter16;
    316 extern VP8SimpleFilterFunc VP8SimpleHFilter16;
    317 extern VP8SimpleFilterFunc VP8SimpleVFilter16i;  // filter 3 inner edges
    318 extern VP8SimpleFilterFunc VP8SimpleHFilter16i;
    319 
    320 // regular filter (on both macroblock edges and inner edges)
    321 typedef void (*VP8LumaFilterFunc)(uint8_t* luma, int stride,
    322                                   int thresh, int ithresh, int hev_t);
    323 typedef void (*VP8ChromaFilterFunc)(uint8_t* u, uint8_t* v, int stride,
    324                                     int thresh, int ithresh, int hev_t);
    325 // on outer edge
    326 extern VP8LumaFilterFunc VP8VFilter16;
    327 extern VP8LumaFilterFunc VP8HFilter16;
    328 extern VP8ChromaFilterFunc VP8VFilter8;
    329 extern VP8ChromaFilterFunc VP8HFilter8;
    330 
    331 // on inner edge
    332 extern VP8LumaFilterFunc VP8VFilter16i;   // filtering 3 inner edges altogether
    333 extern VP8LumaFilterFunc VP8HFilter16i;
    334 extern VP8ChromaFilterFunc VP8VFilter8i;  // filtering u and v altogether
    335 extern VP8ChromaFilterFunc VP8HFilter8i;
    336 
    337 // Dithering. Combines dithering values (centered around 128) with dst[],
    338 // according to: dst[] = clip(dst[] + (((dither[]-128) + 8) >> 4)
    339 #define VP8_DITHER_DESCALE 4
    340 #define VP8_DITHER_DESCALE_ROUNDER (1 << (VP8_DITHER_DESCALE - 1))
    341 #define VP8_DITHER_AMP_BITS 7
    342 #define VP8_DITHER_AMP_CENTER (1 << VP8_DITHER_AMP_BITS)
    343 extern void (*VP8DitherCombine8x8)(const uint8_t* dither, uint8_t* dst,
    344                                    int dst_stride);
    345 
    346 // must be called before anything using the above
    347 void VP8DspInit(void);
    348 
    349 //------------------------------------------------------------------------------
    350 // WebP I/O
    351 
    352 #define FANCY_UPSAMPLING   // undefined to remove fancy upsampling support
    353 
    354 // Convert a pair of y/u/v lines together to the output rgb/a colorspace.
    355 // bottom_y can be NULL if only one line of output is needed (at top/bottom).
    356 typedef void (*WebPUpsampleLinePairFunc)(
    357     const uint8_t* top_y, const uint8_t* bottom_y,
    358     const uint8_t* top_u, const uint8_t* top_v,
    359     const uint8_t* cur_u, const uint8_t* cur_v,
    360     uint8_t* top_dst, uint8_t* bottom_dst, int len);
    361 
    362 #ifdef FANCY_UPSAMPLING
    363 
    364 // Fancy upsampling functions to convert YUV to RGB(A) modes
    365 extern WebPUpsampleLinePairFunc WebPUpsamplers[/* MODE_LAST */];
    366 
    367 #endif    // FANCY_UPSAMPLING
    368 
    369 // Per-row point-sampling methods.
    370 typedef void (*WebPSamplerRowFunc)(const uint8_t* y,
    371                                    const uint8_t* u, const uint8_t* v,
    372                                    uint8_t* dst, int len);
    373 // Generic function to apply 'WebPSamplerRowFunc' to the whole plane:
    374 void WebPSamplerProcessPlane(const uint8_t* y, int y_stride,
    375                              const uint8_t* u, const uint8_t* v, int uv_stride,
    376                              uint8_t* dst, int dst_stride,
    377                              int width, int height, WebPSamplerRowFunc func);
    378 
    379 // Sampling functions to convert rows of YUV to RGB(A)
    380 extern WebPSamplerRowFunc WebPSamplers[/* MODE_LAST */];
    381 
    382 // General function for converting two lines of ARGB or RGBA.
    383 // 'alpha_is_last' should be true if 0xff000000 is stored in memory as
    384 // as 0x00, 0x00, 0x00, 0xff (little endian).
    385 WebPUpsampleLinePairFunc WebPGetLinePairConverter(int alpha_is_last);
    386 
    387 // YUV444->RGB converters
    388 typedef void (*WebPYUV444Converter)(const uint8_t* y,
    389                                     const uint8_t* u, const uint8_t* v,
    390                                     uint8_t* dst, int len);
    391 
    392 extern WebPYUV444Converter WebPYUV444Converters[/* MODE_LAST */];
    393 
    394 // Must be called before using the WebPUpsamplers[] (and for premultiplied
    395 // colorspaces like rgbA, rgbA4444, etc)
    396 void WebPInitUpsamplers(void);
    397 // Must be called before using WebPSamplers[]
    398 void WebPInitSamplers(void);
    399 // Must be called before using WebPYUV444Converters[]
    400 void WebPInitYUV444Converters(void);
    401 
    402 //------------------------------------------------------------------------------
    403 // ARGB -> YUV converters
    404 
    405 // Convert ARGB samples to luma Y.
    406 extern void (*WebPConvertARGBToY)(const uint32_t* argb, uint8_t* y, int width);
    407 // Convert ARGB samples to U/V with downsampling. do_store should be '1' for
    408 // even lines and '0' for odd ones. 'src_width' is the original width, not
    409 // the U/V one.
    410 extern void (*WebPConvertARGBToUV)(const uint32_t* argb, uint8_t* u, uint8_t* v,
    411                                    int src_width, int do_store);
    412 
    413 // Convert a row of accumulated (four-values) of rgba32 toward U/V
    414 extern void (*WebPConvertRGBA32ToUV)(const uint16_t* rgb,
    415                                      uint8_t* u, uint8_t* v, int width);
    416 
    417 // Convert RGB or BGR to Y
    418 extern void (*WebPConvertRGB24ToY)(const uint8_t* rgb, uint8_t* y, int width);
    419 extern void (*WebPConvertBGR24ToY)(const uint8_t* bgr, uint8_t* y, int width);
    420 
    421 // used for plain-C fallback.
    422 extern void WebPConvertARGBToUV_C(const uint32_t* argb, uint8_t* u, uint8_t* v,
    423                                   int src_width, int do_store);
    424 extern void WebPConvertRGBA32ToUV_C(const uint16_t* rgb,
    425                                     uint8_t* u, uint8_t* v, int width);
    426 
    427 // utilities for accurate RGB->YUV conversion
    428 extern uint64_t (*WebPSharpYUVUpdateY)(const uint16_t* src, const uint16_t* ref,
    429                                        uint16_t* dst, int len);
    430 extern void (*WebPSharpYUVUpdateRGB)(const int16_t* src, const int16_t* ref,
    431                                      int16_t* dst, int len);
    432 extern void (*WebPSharpYUVFilterRow)(const int16_t* A, const int16_t* B,
    433                                      int len,
    434                                      const uint16_t* best_y, uint16_t* out);
    435 
    436 // Must be called before using the above.
    437 void WebPInitConvertARGBToYUV(void);
    438 
    439 //------------------------------------------------------------------------------
    440 // Rescaler
    441 
    442 struct WebPRescaler;
    443 
    444 // Import a row of data and save its contribution in the rescaler.
    445 // 'channel' denotes the channel number to be imported. 'Expand' corresponds to
    446 // the wrk->x_expand case. Otherwise, 'Shrink' is to be used.
    447 typedef void (*WebPRescalerImportRowFunc)(struct WebPRescaler* const wrk,
    448                                           const uint8_t* src);
    449 
    450 extern WebPRescalerImportRowFunc WebPRescalerImportRowExpand;
    451 extern WebPRescalerImportRowFunc WebPRescalerImportRowShrink;
    452 
    453 // Export one row (starting at x_out position) from rescaler.
    454 // 'Expand' corresponds to the wrk->y_expand case.
    455 // Otherwise 'Shrink' is to be used
    456 typedef void (*WebPRescalerExportRowFunc)(struct WebPRescaler* const wrk);
    457 extern WebPRescalerExportRowFunc WebPRescalerExportRowExpand;
    458 extern WebPRescalerExportRowFunc WebPRescalerExportRowShrink;
    459 
    460 // Plain-C implementation, as fall-back.
    461 extern void WebPRescalerImportRowExpandC(struct WebPRescaler* const wrk,
    462                                          const uint8_t* src);
    463 extern void WebPRescalerImportRowShrinkC(struct WebPRescaler* const wrk,
    464                                          const uint8_t* src);
    465 extern void WebPRescalerExportRowExpandC(struct WebPRescaler* const wrk);
    466 extern void WebPRescalerExportRowShrinkC(struct WebPRescaler* const wrk);
    467 
    468 // Main entry calls:
    469 extern void WebPRescalerImportRow(struct WebPRescaler* const wrk,
    470                                   const uint8_t* src);
    471 // Export one row (starting at x_out position) from rescaler.
    472 extern void WebPRescalerExportRow(struct WebPRescaler* const wrk);
    473 
    474 // Must be called first before using the above.
    475 void WebPRescalerDspInit(void);
    476 
    477 //------------------------------------------------------------------------------
    478 // Utilities for processing transparent channel.
    479 
    480 // Apply alpha pre-multiply on an rgba, bgra or argb plane of size w * h.
    481 // alpha_first should be 0 for argb, 1 for rgba or bgra (where alpha is last).
    482 extern void (*WebPApplyAlphaMultiply)(
    483     uint8_t* rgba, int alpha_first, int w, int h, int stride);
    484 
    485 // Same, buf specifically for RGBA4444 format
    486 extern void (*WebPApplyAlphaMultiply4444)(
    487     uint8_t* rgba4444, int w, int h, int stride);
    488 
    489 // Dispatch the values from alpha[] plane to the ARGB destination 'dst'.
    490 // Returns true if alpha[] plane has non-trivial values different from 0xff.
    491 extern int (*WebPDispatchAlpha)(const uint8_t* alpha, int alpha_stride,
    492                                 int width, int height,
    493                                 uint8_t* dst, int dst_stride);
    494 
    495 // Transfer packed 8b alpha[] values to green channel in dst[], zero'ing the
    496 // A/R/B values. 'dst_stride' is the stride for dst[] in uint32_t units.
    497 extern void (*WebPDispatchAlphaToGreen)(const uint8_t* alpha, int alpha_stride,
    498                                         int width, int height,
    499                                         uint32_t* dst, int dst_stride);
    500 
    501 // Extract the alpha values from 32b values in argb[] and pack them into alpha[]
    502 // (this is the opposite of WebPDispatchAlpha).
    503 // Returns true if there's only trivial 0xff alpha values.
    504 extern int (*WebPExtractAlpha)(const uint8_t* argb, int argb_stride,
    505                                int width, int height,
    506                                uint8_t* alpha, int alpha_stride);
    507 
    508 // Extract the green values from 32b values in argb[] and pack them into alpha[]
    509 // (this is the opposite of WebPDispatchAlphaToGreen).
    510 extern void (*WebPExtractGreen)(const uint32_t* argb, uint8_t* alpha, int size);
    511 
    512 // Pre-Multiply operation transforms x into x * A / 255  (where x=Y,R,G or B).
    513 // Un-Multiply operation transforms x into x * 255 / A.
    514 
    515 // Pre-Multiply or Un-Multiply (if 'inverse' is true) argb values in a row.
    516 extern void (*WebPMultARGBRow)(uint32_t* const ptr, int width, int inverse);
    517 
    518 // Same a WebPMultARGBRow(), but for several rows.
    519 void WebPMultARGBRows(uint8_t* ptr, int stride, int width, int num_rows,
    520                       int inverse);
    521 
    522 // Same for a row of single values, with side alpha values.
    523 extern void (*WebPMultRow)(uint8_t* const ptr, const uint8_t* const alpha,
    524                            int width, int inverse);
    525 
    526 // Same a WebPMultRow(), but for several 'num_rows' rows.
    527 void WebPMultRows(uint8_t* ptr, int stride,
    528                   const uint8_t* alpha, int alpha_stride,
    529                   int width, int num_rows, int inverse);
    530 
    531 // Plain-C versions, used as fallback by some implementations.
    532 void WebPMultRowC(uint8_t* const ptr, const uint8_t* const alpha,
    533                   int width, int inverse);
    534 void WebPMultARGBRowC(uint32_t* const ptr, int width, int inverse);
    535 
    536 // To be called first before using the above.
    537 void WebPInitAlphaProcessing(void);
    538 
    539 // ARGB packing function: a/r/g/b input is rgba or bgra order.
    540 extern void (*VP8PackARGB)(const uint8_t* a, const uint8_t* r,
    541                            const uint8_t* g, const uint8_t* b, int len,
    542                            uint32_t* out);
    543 
    544 // RGB packing function. 'step' can be 3 or 4. r/g/b input is rgb or bgr order.
    545 extern void (*VP8PackRGB)(const uint8_t* r, const uint8_t* g, const uint8_t* b,
    546                           int len, int step, uint32_t* out);
    547 
    548 // To be called first before using the above.
    549 void VP8EncDspARGBInit(void);
    550 
    551 //------------------------------------------------------------------------------
    552 // Filter functions
    553 
    554 typedef enum {     // Filter types.
    555   WEBP_FILTER_NONE = 0,
    556   WEBP_FILTER_HORIZONTAL,
    557   WEBP_FILTER_VERTICAL,
    558   WEBP_FILTER_GRADIENT,
    559   WEBP_FILTER_LAST = WEBP_FILTER_GRADIENT + 1,  // end marker
    560   WEBP_FILTER_BEST,    // meta-types
    561   WEBP_FILTER_FAST
    562 } WEBP_FILTER_TYPE;
    563 
    564 typedef void (*WebPFilterFunc)(const uint8_t* in, int width, int height,
    565                                int stride, uint8_t* out);
    566 // In-place un-filtering.
    567 // Warning! 'prev_line' pointer can be equal to 'cur_line' or 'preds'.
    568 typedef void (*WebPUnfilterFunc)(const uint8_t* prev_line, const uint8_t* preds,
    569                                  uint8_t* cur_line, int width);
    570 
    571 // Filter the given data using the given predictor.
    572 // 'in' corresponds to a 2-dimensional pixel array of size (stride * height)
    573 // in raster order.
    574 // 'stride' is number of bytes per scan line (with possible padding).
    575 // 'out' should be pre-allocated.
    576 extern WebPFilterFunc WebPFilters[WEBP_FILTER_LAST];
    577 
    578 // In-place reconstruct the original data from the given filtered data.
    579 // The reconstruction will be done for 'num_rows' rows starting from 'row'
    580 // (assuming rows upto 'row - 1' are already reconstructed).
    581 extern WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST];
    582 
    583 // To be called first before using the above.
    584 void VP8FiltersInit(void);
    585 
    586 #ifdef __cplusplus
    587 }    // extern "C"
    588 #endif
    589 
    590 #endif  /* WEBP_DSP_DSP_H_ */
    591