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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 #include "../webp/types.h"
     18 #include "../utils/utils.h"
     19 
     20 #ifdef __cplusplus
     21 extern "C" {
     22 #endif
     23 
     24 #define BPS 32   // this is the common stride for enc/dec
     25 
     26 //------------------------------------------------------------------------------
     27 // CPU detection
     28 
     29 #if defined(__GNUC__)
     30 # define LOCAL_GCC_VERSION ((__GNUC__ << 8) | __GNUC_MINOR__)
     31 # define LOCAL_GCC_PREREQ(maj, min) \
     32     (LOCAL_GCC_VERSION >= (((maj) << 8) | (min)))
     33 #else
     34 # define LOCAL_GCC_VERSION 0
     35 # define LOCAL_GCC_PREREQ(maj, min) 0
     36 #endif
     37 
     38 #ifndef __has_builtin
     39 # define __has_builtin(x) 0
     40 #endif
     41 
     42 #if defined(_MSC_VER) && _MSC_VER > 1310 && \
     43     (defined(_M_X64) || defined(_M_IX86))
     44 #define WEBP_MSC_SSE2  // Visual C++ SSE2 targets
     45 #endif
     46 
     47 #if defined(_MSC_VER) && _MSC_VER >= 1500 && \
     48     (defined(_M_X64) || defined(_M_IX86))
     49 #define WEBP_MSC_SSE41  // Visual C++ SSE4.1 targets
     50 #endif
     51 
     52 // WEBP_HAVE_* are used to indicate the presence of the instruction set in dsp
     53 // files without intrinsics, allowing the corresponding Init() to be called.
     54 // Files containing intrinsics will need to be built targeting the instruction
     55 // set so should succeed on one of the earlier tests.
     56 #if defined(__SSE2__) || defined(WEBP_MSC_SSE2) || defined(WEBP_HAVE_SSE2)
     57 #define WEBP_USE_SSE2
     58 #endif
     59 
     60 #if defined(__SSE4_1__) || defined(WEBP_MSC_SSE41) || defined(WEBP_HAVE_SSE41)
     61 #define WEBP_USE_SSE41
     62 #endif
     63 
     64 #if defined(__AVX2__) || defined(WEBP_HAVE_AVX2)
     65 #define WEBP_USE_AVX2
     66 #endif
     67 
     68 #if defined(__ANDROID__) && defined(__ARM_ARCH_7A__)
     69 #define WEBP_ANDROID_NEON  // Android targets that might support NEON
     70 #endif
     71 
     72 // The intrinsics currently cause compiler errors with arm-nacl-gcc and the
     73 // inline assembly would need to be modified for use with Native Client.
     74 #if (defined(__ARM_NEON__) || defined(__aarch64__)) \
     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 // This macro prevents thread_sanitizer from reporting known concurrent writes.
     96 #define WEBP_TSAN_IGNORE_FUNCTION
     97 #if defined(__has_feature)
     98 #if __has_feature(thread_sanitizer)
     99 #undef WEBP_TSAN_IGNORE_FUNCTION
    100 #define WEBP_TSAN_IGNORE_FUNCTION __attribute__((no_sanitize_thread))
    101 #endif
    102 #endif
    103 
    104 typedef enum {
    105   kSSE2,
    106   kSSE3,
    107   kSSE4_1,
    108   kAVX,
    109   kAVX2,
    110   kNEON,
    111   kMIPS32,
    112   kMIPSdspR2
    113 } CPUFeature;
    114 // returns true if the CPU supports the feature.
    115 typedef int (*VP8CPUInfo)(CPUFeature feature);
    116 WEBP_EXTERN(VP8CPUInfo) VP8GetCPUInfo;
    117 
    118 //------------------------------------------------------------------------------
    119 // Init stub generator
    120 
    121 // Defines an init function stub to ensure each module exposes a symbol,
    122 // avoiding a compiler warning.
    123 #define WEBP_DSP_INIT_STUB(func) \
    124   extern void func(void); \
    125   WEBP_TSAN_IGNORE_FUNCTION void func(void) {}
    126 
    127 //------------------------------------------------------------------------------
    128 // Encoding
    129 
    130 // Transforms
    131 // VP8Idct: Does one of two inverse transforms. If do_two is set, the transforms
    132 //          will be done for (ref, in, dst) and (ref + 4, in + 16, dst + 4).
    133 typedef void (*VP8Idct)(const uint8_t* ref, const int16_t* in, uint8_t* dst,
    134                         int do_two);
    135 typedef void (*VP8Fdct)(const uint8_t* src, const uint8_t* ref, int16_t* out);
    136 typedef void (*VP8WHT)(const int16_t* in, int16_t* out);
    137 extern VP8Idct VP8ITransform;
    138 extern VP8Fdct VP8FTransform;
    139 extern VP8Fdct VP8FTransform2;   // performs two transforms at a time
    140 extern VP8WHT VP8FTransformWHT;
    141 // Predictions
    142 // *dst is the destination block. *top and *left can be NULL.
    143 typedef void (*VP8IntraPreds)(uint8_t *dst, const uint8_t* left,
    144                               const uint8_t* top);
    145 typedef void (*VP8Intra4Preds)(uint8_t *dst, const uint8_t* top);
    146 extern VP8Intra4Preds VP8EncPredLuma4;
    147 extern VP8IntraPreds VP8EncPredLuma16;
    148 extern VP8IntraPreds VP8EncPredChroma8;
    149 
    150 typedef int (*VP8Metric)(const uint8_t* pix, const uint8_t* ref);
    151 extern VP8Metric VP8SSE16x16, VP8SSE16x8, VP8SSE8x8, VP8SSE4x4;
    152 typedef int (*VP8WMetric)(const uint8_t* pix, const uint8_t* ref,
    153                           const uint16_t* const weights);
    154 extern VP8WMetric VP8TDisto4x4, VP8TDisto16x16;
    155 
    156 typedef void (*VP8BlockCopy)(const uint8_t* src, uint8_t* dst);
    157 extern VP8BlockCopy VP8Copy4x4;
    158 extern VP8BlockCopy VP8Copy16x8;
    159 // Quantization
    160 struct VP8Matrix;   // forward declaration
    161 typedef int (*VP8QuantizeBlock)(int16_t in[16], int16_t out[16],
    162                                 const struct VP8Matrix* const mtx);
    163 // Same as VP8QuantizeBlock, but quantizes two consecutive blocks.
    164 typedef int (*VP8Quantize2Blocks)(int16_t in[32], int16_t out[32],
    165                                   const struct VP8Matrix* const mtx);
    166 
    167 extern VP8QuantizeBlock VP8EncQuantizeBlock;
    168 extern VP8Quantize2Blocks VP8EncQuantize2Blocks;
    169 
    170 // specific to 2nd transform:
    171 typedef int (*VP8QuantizeBlockWHT)(int16_t in[16], int16_t out[16],
    172                                    const struct VP8Matrix* const mtx);
    173 extern VP8QuantizeBlockWHT VP8EncQuantizeBlockWHT;
    174 
    175 extern const int VP8DspScan[16 + 4 + 4];
    176 
    177 // Collect histogram for susceptibility calculation.
    178 #define MAX_COEFF_THRESH   31   // size of histogram used by CollectHistogram.
    179 typedef struct {
    180   // We only need to store max_value and last_non_zero, not the distribution.
    181   int max_value;
    182   int last_non_zero;
    183 } VP8Histogram;
    184 typedef void (*VP8CHisto)(const uint8_t* ref, const uint8_t* pred,
    185                           int start_block, int end_block,
    186                           VP8Histogram* const histo);
    187 extern VP8CHisto VP8CollectHistogram;
    188 // General-purpose util function to help VP8CollectHistogram().
    189 void VP8SetHistogramData(const int distribution[MAX_COEFF_THRESH + 1],
    190                          VP8Histogram* const histo);
    191 
    192 // must be called before using any of the above
    193 void VP8EncDspInit(void);
    194 
    195 //------------------------------------------------------------------------------
    196 // cost functions (encoding)
    197 
    198 extern const uint16_t VP8EntropyCost[256];        // 8bit fixed-point log(p)
    199 // approximate cost per level:
    200 extern const uint16_t VP8LevelFixedCosts[2047 /*MAX_LEVEL*/ + 1];
    201 extern const uint8_t VP8EncBands[16 + 1];
    202 
    203 struct VP8Residual;
    204 typedef void (*VP8SetResidualCoeffsFunc)(const int16_t* const coeffs,
    205                                          struct VP8Residual* const res);
    206 extern VP8SetResidualCoeffsFunc VP8SetResidualCoeffs;
    207 
    208 // Cost calculation function.
    209 typedef int (*VP8GetResidualCostFunc)(int ctx0,
    210                                       const struct VP8Residual* const res);
    211 extern VP8GetResidualCostFunc VP8GetResidualCost;
    212 
    213 // must be called before anything using the above
    214 void VP8EncDspCostInit(void);
    215 
    216 //------------------------------------------------------------------------------
    217 // Decoding
    218 
    219 typedef void (*VP8DecIdct)(const int16_t* coeffs, uint8_t* dst);
    220 // when doing two transforms, coeffs is actually int16_t[2][16].
    221 typedef void (*VP8DecIdct2)(const int16_t* coeffs, uint8_t* dst, int do_two);
    222 extern VP8DecIdct2 VP8Transform;
    223 extern VP8DecIdct VP8TransformAC3;
    224 extern VP8DecIdct VP8TransformUV;
    225 extern VP8DecIdct VP8TransformDC;
    226 extern VP8DecIdct VP8TransformDCUV;
    227 extern VP8WHT VP8TransformWHT;
    228 
    229 // *dst is the destination block, with stride BPS. Boundary samples are
    230 // assumed accessible when needed.
    231 typedef void (*VP8PredFunc)(uint8_t* dst);
    232 extern VP8PredFunc VP8PredLuma16[/* NUM_B_DC_MODES */];
    233 extern VP8PredFunc VP8PredChroma8[/* NUM_B_DC_MODES */];
    234 extern VP8PredFunc VP8PredLuma4[/* NUM_BMODES */];
    235 
    236 // clipping tables (for filtering)
    237 extern const int8_t* const VP8ksclip1;  // clips [-1020, 1020] to [-128, 127]
    238 extern const int8_t* const VP8ksclip2;  // clips [-112, 112] to [-16, 15]
    239 extern const uint8_t* const VP8kclip1;  // clips [-255,511] to [0,255]
    240 extern const uint8_t* const VP8kabs0;   // abs(x) for x in [-255,255]
    241 // must be called first
    242 void VP8InitClipTables(void);
    243 
    244 // simple filter (only for luma)
    245 typedef void (*VP8SimpleFilterFunc)(uint8_t* p, int stride, int thresh);
    246 extern VP8SimpleFilterFunc VP8SimpleVFilter16;
    247 extern VP8SimpleFilterFunc VP8SimpleHFilter16;
    248 extern VP8SimpleFilterFunc VP8SimpleVFilter16i;  // filter 3 inner edges
    249 extern VP8SimpleFilterFunc VP8SimpleHFilter16i;
    250 
    251 // regular filter (on both macroblock edges and inner edges)
    252 typedef void (*VP8LumaFilterFunc)(uint8_t* luma, int stride,
    253                                   int thresh, int ithresh, int hev_t);
    254 typedef void (*VP8ChromaFilterFunc)(uint8_t* u, uint8_t* v, int stride,
    255                                     int thresh, int ithresh, int hev_t);
    256 // on outer edge
    257 extern VP8LumaFilterFunc VP8VFilter16;
    258 extern VP8LumaFilterFunc VP8HFilter16;
    259 extern VP8ChromaFilterFunc VP8VFilter8;
    260 extern VP8ChromaFilterFunc VP8HFilter8;
    261 
    262 // on inner edge
    263 extern VP8LumaFilterFunc VP8VFilter16i;   // filtering 3 inner edges altogether
    264 extern VP8LumaFilterFunc VP8HFilter16i;
    265 extern VP8ChromaFilterFunc VP8VFilter8i;  // filtering u and v altogether
    266 extern VP8ChromaFilterFunc VP8HFilter8i;
    267 
    268 // must be called before anything using the above
    269 void VP8DspInit(void);
    270 
    271 //------------------------------------------------------------------------------
    272 // WebP I/O
    273 
    274 #define FANCY_UPSAMPLING   // undefined to remove fancy upsampling support
    275 
    276 // Convert a pair of y/u/v lines together to the output rgb/a colorspace.
    277 // bottom_y can be NULL if only one line of output is needed (at top/bottom).
    278 typedef void (*WebPUpsampleLinePairFunc)(
    279     const uint8_t* top_y, const uint8_t* bottom_y,
    280     const uint8_t* top_u, const uint8_t* top_v,
    281     const uint8_t* cur_u, const uint8_t* cur_v,
    282     uint8_t* top_dst, uint8_t* bottom_dst, int len);
    283 
    284 #ifdef FANCY_UPSAMPLING
    285 
    286 // Fancy upsampling functions to convert YUV to RGB(A) modes
    287 extern WebPUpsampleLinePairFunc WebPUpsamplers[/* MODE_LAST */];
    288 
    289 #endif    // FANCY_UPSAMPLING
    290 
    291 // Per-row point-sampling methods.
    292 typedef void (*WebPSamplerRowFunc)(const uint8_t* y,
    293                                    const uint8_t* u, const uint8_t* v,
    294                                    uint8_t* dst, int len);
    295 // Generic function to apply 'WebPSamplerRowFunc' to the whole plane:
    296 void WebPSamplerProcessPlane(const uint8_t* y, int y_stride,
    297                              const uint8_t* u, const uint8_t* v, int uv_stride,
    298                              uint8_t* dst, int dst_stride,
    299                              int width, int height, WebPSamplerRowFunc func);
    300 
    301 // Sampling functions to convert rows of YUV to RGB(A)
    302 extern WebPSamplerRowFunc WebPSamplers[/* MODE_LAST */];
    303 
    304 // General function for converting two lines of ARGB or RGBA.
    305 // 'alpha_is_last' should be true if 0xff000000 is stored in memory as
    306 // as 0x00, 0x00, 0x00, 0xff (little endian).
    307 WebPUpsampleLinePairFunc WebPGetLinePairConverter(int alpha_is_last);
    308 
    309 // YUV444->RGB converters
    310 typedef void (*WebPYUV444Converter)(const uint8_t* y,
    311                                     const uint8_t* u, const uint8_t* v,
    312                                     uint8_t* dst, int len);
    313 
    314 extern WebPYUV444Converter WebPYUV444Converters[/* MODE_LAST */];
    315 
    316 // Must be called before using the WebPUpsamplers[] (and for premultiplied
    317 // colorspaces like rgbA, rgbA4444, etc)
    318 void WebPInitUpsamplers(void);
    319 // Must be called before using WebPSamplers[]
    320 void WebPInitSamplers(void);
    321 // Must be called before using WebPYUV444Converters[]
    322 void WebPInitYUV444Converters(void);
    323 
    324 //------------------------------------------------------------------------------
    325 // ARGB -> YUV converters
    326 
    327 // Convert ARGB samples to luma Y.
    328 extern void (*WebPConvertARGBToY)(const uint32_t* argb, uint8_t* y, int width);
    329 // Convert ARGB samples to U/V with downsampling. do_store should be '1' for
    330 // even lines and '0' for odd ones. 'src_width' is the original width, not
    331 // the U/V one.
    332 extern void (*WebPConvertARGBToUV)(const uint32_t* argb, uint8_t* u, uint8_t* v,
    333                                    int src_width, int do_store);
    334 
    335 // Convert a row of accumulated (four-values) of rgba32 toward U/V
    336 extern void (*WebPConvertRGBA32ToUV)(const uint16_t* rgb,
    337                                      uint8_t* u, uint8_t* v, int width);
    338 
    339 // Convert RGB or BGR to Y
    340 extern void (*WebPConvertRGB24ToY)(const uint8_t* rgb, uint8_t* y, int width);
    341 extern void (*WebPConvertBGR24ToY)(const uint8_t* bgr, uint8_t* y, int width);
    342 
    343 // used for plain-C fallback.
    344 extern void WebPConvertARGBToUV_C(const uint32_t* argb, uint8_t* u, uint8_t* v,
    345                                   int src_width, int do_store);
    346 extern void WebPConvertRGBA32ToUV_C(const uint16_t* rgb,
    347                                     uint8_t* u, uint8_t* v, int width);
    348 
    349 // Must be called before using the above.
    350 void WebPInitConvertARGBToYUV(void);
    351 
    352 //------------------------------------------------------------------------------
    353 // Rescaler
    354 
    355 struct WebPRescaler;
    356 
    357 // Import a row of data and save its contribution in the rescaler.
    358 // 'channel' denotes the channel number to be imported. 'Expand' corresponds to
    359 // the wrk->x_expand case. Otherwise, 'Shrink' is to be used.
    360 typedef void (*WebPRescalerImportRowFunc)(struct WebPRescaler* const wrk,
    361                                           const uint8_t* src);
    362 
    363 extern WebPRescalerImportRowFunc WebPRescalerImportRowExpand;
    364 extern WebPRescalerImportRowFunc WebPRescalerImportRowShrink;
    365 
    366 // Export one row (starting at x_out position) from rescaler.
    367 // 'Expand' corresponds to the wrk->y_expand case.
    368 // Otherwise 'Shrink' is to be used
    369 typedef void (*WebPRescalerExportRowFunc)(struct WebPRescaler* const wrk);
    370 extern WebPRescalerExportRowFunc WebPRescalerExportRowExpand;
    371 extern WebPRescalerExportRowFunc WebPRescalerExportRowShrink;
    372 
    373 // Plain-C implementation, as fall-back.
    374 extern void WebPRescalerImportRowExpandC(struct WebPRescaler* const wrk,
    375                                          const uint8_t* src);
    376 extern void WebPRescalerImportRowShrinkC(struct WebPRescaler* const wrk,
    377                                          const uint8_t* src);
    378 extern void WebPRescalerExportRowExpandC(struct WebPRescaler* const wrk);
    379 extern void WebPRescalerExportRowShrinkC(struct WebPRescaler* const wrk);
    380 
    381 // Main entry calls:
    382 extern void WebPRescalerImportRow(struct WebPRescaler* const wrk,
    383                                   const uint8_t* src);
    384 // Export one row (starting at x_out position) from rescaler.
    385 extern void WebPRescalerExportRow(struct WebPRescaler* const wrk);
    386 
    387 // Must be called first before using the above.
    388 void WebPRescalerDspInit(void);
    389 
    390 //------------------------------------------------------------------------------
    391 // Utilities for processing transparent channel.
    392 
    393 // Apply alpha pre-multiply on an rgba, bgra or argb plane of size w * h.
    394 // alpha_first should be 0 for argb, 1 for rgba or bgra (where alpha is last).
    395 extern void (*WebPApplyAlphaMultiply)(
    396     uint8_t* rgba, int alpha_first, int w, int h, int stride);
    397 
    398 // Same, buf specifically for RGBA4444 format
    399 extern void (*WebPApplyAlphaMultiply4444)(
    400     uint8_t* rgba4444, int w, int h, int stride);
    401 
    402 // Dispatch the values from alpha[] plane to the ARGB destination 'dst'.
    403 // Returns true if alpha[] plane has non-trivial values different from 0xff.
    404 extern int (*WebPDispatchAlpha)(const uint8_t* alpha, int alpha_stride,
    405                                 int width, int height,
    406                                 uint8_t* dst, int dst_stride);
    407 
    408 // Transfer packed 8b alpha[] values to green channel in dst[], zero'ing the
    409 // A/R/B values. 'dst_stride' is the stride for dst[] in uint32_t units.
    410 extern void (*WebPDispatchAlphaToGreen)(const uint8_t* alpha, int alpha_stride,
    411                                         int width, int height,
    412                                         uint32_t* dst, int dst_stride);
    413 
    414 // Extract the alpha values from 32b values in argb[] and pack them into alpha[]
    415 // (this is the opposite of WebPDispatchAlpha).
    416 // Returns true if there's only trivial 0xff alpha values.
    417 extern int (*WebPExtractAlpha)(const uint8_t* argb, int argb_stride,
    418                                int width, int height,
    419                                uint8_t* alpha, int alpha_stride);
    420 
    421 // Pre-Multiply operation transforms x into x * A / 255  (where x=Y,R,G or B).
    422 // Un-Multiply operation transforms x into x * 255 / A.
    423 
    424 // Pre-Multiply or Un-Multiply (if 'inverse' is true) argb values in a row.
    425 extern void (*WebPMultARGBRow)(uint32_t* const ptr, int width, int inverse);
    426 
    427 // Same a WebPMultARGBRow(), but for several rows.
    428 void WebPMultARGBRows(uint8_t* ptr, int stride, int width, int num_rows,
    429                       int inverse);
    430 
    431 // Same for a row of single values, with side alpha values.
    432 extern void (*WebPMultRow)(uint8_t* const ptr, const uint8_t* const alpha,
    433                            int width, int inverse);
    434 
    435 // Same a WebPMultRow(), but for several 'num_rows' rows.
    436 void WebPMultRows(uint8_t* ptr, int stride,
    437                   const uint8_t* alpha, int alpha_stride,
    438                   int width, int num_rows, int inverse);
    439 
    440 // Plain-C versions, used as fallback by some implementations.
    441 void WebPMultRowC(uint8_t* const ptr, const uint8_t* const alpha,
    442                   int width, int inverse);
    443 void WebPMultARGBRowC(uint32_t* const ptr, int width, int inverse);
    444 
    445 // To be called first before using the above.
    446 void WebPInitAlphaProcessing(void);
    447 
    448 // ARGB packing function: a/r/g/b input is rgba or bgra order.
    449 extern void (*VP8PackARGB)(const uint8_t* a, const uint8_t* r,
    450                            const uint8_t* g, const uint8_t* b, int len,
    451                            uint32_t* out);
    452 
    453 // RGB packing function. 'step' can be 3 or 4. r/g/b input is rgb or bgr order.
    454 extern void (*VP8PackRGB)(const uint8_t* r, const uint8_t* g, const uint8_t* b,
    455                           int len, int step, uint32_t* out);
    456 
    457 // To be called first before using the above.
    458 void VP8EncDspARGBInit(void);
    459 
    460 //------------------------------------------------------------------------------
    461 // Filter functions
    462 
    463 typedef enum {     // Filter types.
    464   WEBP_FILTER_NONE = 0,
    465   WEBP_FILTER_HORIZONTAL,
    466   WEBP_FILTER_VERTICAL,
    467   WEBP_FILTER_GRADIENT,
    468   WEBP_FILTER_LAST = WEBP_FILTER_GRADIENT + 1,  // end marker
    469   WEBP_FILTER_BEST,    // meta-types
    470   WEBP_FILTER_FAST
    471 } WEBP_FILTER_TYPE;
    472 
    473 typedef void (*WebPFilterFunc)(const uint8_t* in, int width, int height,
    474                                int stride, uint8_t* out);
    475 typedef void (*WebPUnfilterFunc)(int width, int height, int stride,
    476                                  int row, int num_rows, uint8_t* data);
    477 
    478 // Filter the given data using the given predictor.
    479 // 'in' corresponds to a 2-dimensional pixel array of size (stride * height)
    480 // in raster order.
    481 // 'stride' is number of bytes per scan line (with possible padding).
    482 // 'out' should be pre-allocated.
    483 extern WebPFilterFunc WebPFilters[WEBP_FILTER_LAST];
    484 
    485 // In-place reconstruct the original data from the given filtered data.
    486 // The reconstruction will be done for 'num_rows' rows starting from 'row'
    487 // (assuming rows upto 'row - 1' are already reconstructed).
    488 extern WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST];
    489 
    490 // To be called first before using the above.
    491 void VP8FiltersInit(void);
    492 
    493 #ifdef __cplusplus
    494 }    // extern "C"
    495 #endif
    496 
    497 #endif  /* WEBP_DSP_DSP_H_ */
    498