• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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@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 #if defined(__AVX2__) || defined(WEBP_HAVE_AVX2)
80 #define WEBP_USE_AVX2
81 #endif
82 
83 // The intrinsics currently cause compiler errors with arm-nacl-gcc and the
84 // inline assembly would need to be modified for use with Native Client.
85 #if (defined(__ARM_NEON__) || \
86      defined(__aarch64__) || defined(WEBP_HAVE_NEON)) && \
87     !defined(__native_client__)
88 #define WEBP_USE_NEON
89 #endif
90 
91 #if !defined(WEBP_USE_NEON) && defined(__ANDROID__) && \
92     defined(__ARM_ARCH_7A__) && defined(HAVE_CPU_FEATURES_H)
93 #define WEBP_ANDROID_NEON  // Android targets that may have NEON
94 #define WEBP_USE_NEON
95 #endif
96 
97 #if defined(_MSC_VER) && _MSC_VER >= 1700 && defined(_M_ARM)
98 #define WEBP_USE_NEON
99 #define WEBP_USE_INTRINSICS
100 #endif
101 
102 #if defined(__mips__) && !defined(__mips64) && \
103     defined(__mips_isa_rev) && (__mips_isa_rev >= 1) && (__mips_isa_rev < 6)
104 #define WEBP_USE_MIPS32
105 #if (__mips_isa_rev >= 2)
106 #define WEBP_USE_MIPS32_R2
107 #if defined(__mips_dspr2) || (defined(__mips_dsp_rev) && __mips_dsp_rev >= 2)
108 #define WEBP_USE_MIPS_DSP_R2
109 #endif
110 #endif
111 #endif
112 
113 #if defined(__mips_msa) && defined(__mips_isa_rev) && (__mips_isa_rev >= 5)
114 #define WEBP_USE_MSA
115 #endif
116 
117 #endif  /* EMSCRIPTEN */
118 
119 #ifndef WEBP_DSP_OMIT_C_CODE
120 #define WEBP_DSP_OMIT_C_CODE 1
121 #endif
122 
123 #if (defined(__aarch64__) || defined(__ARM_NEON__)) && WEBP_DSP_OMIT_C_CODE
124 #define WEBP_NEON_OMIT_C_CODE 1
125 #else
126 #define WEBP_NEON_OMIT_C_CODE 0
127 #endif
128 
129 #if !(LOCAL_CLANG_PREREQ(3,8) || LOCAL_GCC_PREREQ(4,8) || defined(__aarch64__))
130 #define WEBP_NEON_WORK_AROUND_GCC 1
131 #else
132 #define WEBP_NEON_WORK_AROUND_GCC 0
133 #endif
134 
135 // This macro prevents thread_sanitizer from reporting known concurrent writes.
136 #define WEBP_TSAN_IGNORE_FUNCTION
137 #if defined(__has_feature)
138 #if __has_feature(thread_sanitizer)
139 #undef WEBP_TSAN_IGNORE_FUNCTION
140 #define WEBP_TSAN_IGNORE_FUNCTION __attribute__((no_sanitize_thread))
141 #endif
142 #endif
143 
144 #define WEBP_UBSAN_IGNORE_UNDEF
145 #define WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW
146 #if defined(__clang__) && defined(__has_attribute)
147 #if __has_attribute(no_sanitize)
148 // This macro prevents the undefined behavior sanitizer from reporting
149 // failures. This is only meant to silence unaligned loads on platforms that
150 // are known to support them.
151 #undef WEBP_UBSAN_IGNORE_UNDEF
152 #define WEBP_UBSAN_IGNORE_UNDEF \
153   __attribute__((no_sanitize("undefined")))
154 
155 // This macro prevents the undefined behavior sanitizer from reporting
156 // failures related to unsigned integer overflows. This is only meant to
157 // silence cases where this well defined behavior is expected.
158 #undef WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW
159 #define WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW \
160   __attribute__((no_sanitize("unsigned-integer-overflow")))
161 #endif
162 #endif
163 
164 // Regularize the definition of WEBP_SWAP_16BIT_CSP (backward compatibility)
165 #if !defined(WEBP_SWAP_16BIT_CSP)
166 #define WEBP_SWAP_16BIT_CSP 0
167 #endif
168 
169 typedef enum {
170   kSSE2,
171   kSSE3,
172   kSlowSSSE3,  // special feature for slow SSSE3 architectures
173   kSSE4_1,
174   kAVX,
175   kAVX2,
176   kNEON,
177   kMIPS32,
178   kMIPSdspR2,
179   kMSA
180 } CPUFeature;
181 // returns true if the CPU supports the feature.
182 typedef int (*VP8CPUInfo)(CPUFeature feature);
183 WEBP_EXTERN VP8CPUInfo VP8GetCPUInfo;
184 
185 //------------------------------------------------------------------------------
186 // Init stub generator
187 
188 // Defines an init function stub to ensure each module exposes a symbol,
189 // avoiding a compiler warning.
190 #define WEBP_DSP_INIT_STUB(func) \
191   extern void func(void); \
192   WEBP_TSAN_IGNORE_FUNCTION void func(void) {}
193 
194 //------------------------------------------------------------------------------
195 // Encoding
196 
197 // Transforms
198 // VP8Idct: Does one of two inverse transforms. If do_two is set, the transforms
199 //          will be done for (ref, in, dst) and (ref + 4, in + 16, dst + 4).
200 typedef void (*VP8Idct)(const uint8_t* ref, const int16_t* in, uint8_t* dst,
201                         int do_two);
202 typedef void (*VP8Fdct)(const uint8_t* src, const uint8_t* ref, int16_t* out);
203 typedef void (*VP8WHT)(const int16_t* in, int16_t* out);
204 extern VP8Idct VP8ITransform;
205 extern VP8Fdct VP8FTransform;
206 extern VP8Fdct VP8FTransform2;   // performs two transforms at a time
207 extern VP8WHT VP8FTransformWHT;
208 // Predictions
209 // *dst is the destination block. *top and *left can be NULL.
210 typedef void (*VP8IntraPreds)(uint8_t *dst, const uint8_t* left,
211                               const uint8_t* top);
212 typedef void (*VP8Intra4Preds)(uint8_t *dst, const uint8_t* top);
213 extern VP8Intra4Preds VP8EncPredLuma4;
214 extern VP8IntraPreds VP8EncPredLuma16;
215 extern VP8IntraPreds VP8EncPredChroma8;
216 
217 typedef int (*VP8Metric)(const uint8_t* pix, const uint8_t* ref);
218 extern VP8Metric VP8SSE16x16, VP8SSE16x8, VP8SSE8x8, VP8SSE4x4;
219 typedef int (*VP8WMetric)(const uint8_t* pix, const uint8_t* ref,
220                           const uint16_t* const weights);
221 // The weights for VP8TDisto4x4 and VP8TDisto16x16 contain a row-major
222 // 4 by 4 symmetric matrix.
223 extern VP8WMetric VP8TDisto4x4, VP8TDisto16x16;
224 
225 // Compute the average (DC) of four 4x4 blocks.
226 // Each sub-4x4 block #i sum is stored in dc[i].
227 typedef void (*VP8MeanMetric)(const uint8_t* ref, uint32_t dc[4]);
228 extern VP8MeanMetric VP8Mean16x4;
229 
230 typedef void (*VP8BlockCopy)(const uint8_t* src, uint8_t* dst);
231 extern VP8BlockCopy VP8Copy4x4;
232 extern VP8BlockCopy VP8Copy16x8;
233 // Quantization
234 struct VP8Matrix;   // forward declaration
235 typedef int (*VP8QuantizeBlock)(int16_t in[16], int16_t out[16],
236                                 const struct VP8Matrix* const mtx);
237 // Same as VP8QuantizeBlock, but quantizes two consecutive blocks.
238 typedef int (*VP8Quantize2Blocks)(int16_t in[32], int16_t out[32],
239                                   const struct VP8Matrix* const mtx);
240 
241 extern VP8QuantizeBlock VP8EncQuantizeBlock;
242 extern VP8Quantize2Blocks VP8EncQuantize2Blocks;
243 
244 // specific to 2nd transform:
245 typedef int (*VP8QuantizeBlockWHT)(int16_t in[16], int16_t out[16],
246                                    const struct VP8Matrix* const mtx);
247 extern VP8QuantizeBlockWHT VP8EncQuantizeBlockWHT;
248 
249 extern const int VP8DspScan[16 + 4 + 4];
250 
251 // Collect histogram for susceptibility calculation.
252 #define MAX_COEFF_THRESH   31   // size of histogram used by CollectHistogram.
253 typedef struct {
254   // We only need to store max_value and last_non_zero, not the distribution.
255   int max_value;
256   int last_non_zero;
257 } VP8Histogram;
258 typedef void (*VP8CHisto)(const uint8_t* ref, const uint8_t* pred,
259                           int start_block, int end_block,
260                           VP8Histogram* const histo);
261 extern VP8CHisto VP8CollectHistogram;
262 // General-purpose util function to help VP8CollectHistogram().
263 void VP8SetHistogramData(const int distribution[MAX_COEFF_THRESH + 1],
264                          VP8Histogram* const histo);
265 
266 // must be called before using any of the above
267 void VP8EncDspInit(void);
268 
269 //------------------------------------------------------------------------------
270 // cost functions (encoding)
271 
272 extern const uint16_t VP8EntropyCost[256];        // 8bit fixed-point log(p)
273 // approximate cost per level:
274 extern const uint16_t VP8LevelFixedCosts[2047 /*MAX_LEVEL*/ + 1];
275 extern const uint8_t VP8EncBands[16 + 1];
276 
277 struct VP8Residual;
278 typedef void (*VP8SetResidualCoeffsFunc)(const int16_t* const coeffs,
279                                          struct VP8Residual* const res);
280 extern VP8SetResidualCoeffsFunc VP8SetResidualCoeffs;
281 
282 // Cost calculation function.
283 typedef int (*VP8GetResidualCostFunc)(int ctx0,
284                                       const struct VP8Residual* const res);
285 extern VP8GetResidualCostFunc VP8GetResidualCost;
286 
287 // must be called before anything using the above
288 void VP8EncDspCostInit(void);
289 
290 //------------------------------------------------------------------------------
291 // SSIM / PSNR utils
292 
293 // struct for accumulating statistical moments
294 typedef struct {
295   uint32_t w;              // sum(w_i) : sum of weights
296   uint32_t xm, ym;         // sum(w_i * x_i), sum(w_i * y_i)
297   uint32_t xxm, xym, yym;  // sum(w_i * x_i * x_i), etc.
298 } VP8DistoStats;
299 
300 // Compute the final SSIM value
301 // The non-clipped version assumes stats->w = (2 * VP8_SSIM_KERNEL + 1)^2.
302 double VP8SSIMFromStats(const VP8DistoStats* const stats);
303 double VP8SSIMFromStatsClipped(const VP8DistoStats* const stats);
304 
305 #define VP8_SSIM_KERNEL 3   // total size of the kernel: 2 * VP8_SSIM_KERNEL + 1
306 typedef double (*VP8SSIMGetClippedFunc)(const uint8_t* src1, int stride1,
307                                         const uint8_t* src2, int stride2,
308                                         int xo, int yo,  // center position
309                                         int W, int H);   // plane dimension
310 
311 #if !defined(WEBP_REDUCE_SIZE)
312 // This version is called with the guarantee that you can load 8 bytes and
313 // 8 rows at offset src1 and src2
314 typedef double (*VP8SSIMGetFunc)(const uint8_t* src1, int stride1,
315                                  const uint8_t* src2, int stride2);
316 
317 extern VP8SSIMGetFunc VP8SSIMGet;         // unclipped / unchecked
318 extern VP8SSIMGetClippedFunc VP8SSIMGetClipped;   // with clipping
319 #endif
320 
321 #if !defined(WEBP_DISABLE_STATS)
322 typedef uint32_t (*VP8AccumulateSSEFunc)(const uint8_t* src1,
323                                          const uint8_t* src2, int len);
324 extern VP8AccumulateSSEFunc VP8AccumulateSSE;
325 #endif
326 
327 // must be called before using any of the above directly
328 void VP8SSIMDspInit(void);
329 
330 //------------------------------------------------------------------------------
331 // Decoding
332 
333 typedef void (*VP8DecIdct)(const int16_t* coeffs, uint8_t* dst);
334 // when doing two transforms, coeffs is actually int16_t[2][16].
335 typedef void (*VP8DecIdct2)(const int16_t* coeffs, uint8_t* dst, int do_two);
336 extern VP8DecIdct2 VP8Transform;
337 extern VP8DecIdct VP8TransformAC3;
338 extern VP8DecIdct VP8TransformUV;
339 extern VP8DecIdct VP8TransformDC;
340 extern VP8DecIdct VP8TransformDCUV;
341 extern VP8WHT VP8TransformWHT;
342 
343 // *dst is the destination block, with stride BPS. Boundary samples are
344 // assumed accessible when needed.
345 typedef void (*VP8PredFunc)(uint8_t* dst);
346 extern VP8PredFunc VP8PredLuma16[/* NUM_B_DC_MODES */];
347 extern VP8PredFunc VP8PredChroma8[/* NUM_B_DC_MODES */];
348 extern VP8PredFunc VP8PredLuma4[/* NUM_BMODES */];
349 
350 // clipping tables (for filtering)
351 extern const int8_t* const VP8ksclip1;  // clips [-1020, 1020] to [-128, 127]
352 extern const int8_t* const VP8ksclip2;  // clips [-112, 112] to [-16, 15]
353 extern const uint8_t* const VP8kclip1;  // clips [-255,511] to [0,255]
354 extern const uint8_t* const VP8kabs0;   // abs(x) for x in [-255,255]
355 // must be called first
356 void VP8InitClipTables(void);
357 
358 // simple filter (only for luma)
359 typedef void (*VP8SimpleFilterFunc)(uint8_t* p, int stride, int thresh);
360 extern VP8SimpleFilterFunc VP8SimpleVFilter16;
361 extern VP8SimpleFilterFunc VP8SimpleHFilter16;
362 extern VP8SimpleFilterFunc VP8SimpleVFilter16i;  // filter 3 inner edges
363 extern VP8SimpleFilterFunc VP8SimpleHFilter16i;
364 
365 // regular filter (on both macroblock edges and inner edges)
366 typedef void (*VP8LumaFilterFunc)(uint8_t* luma, int stride,
367                                   int thresh, int ithresh, int hev_t);
368 typedef void (*VP8ChromaFilterFunc)(uint8_t* u, uint8_t* v, int stride,
369                                     int thresh, int ithresh, int hev_t);
370 // on outer edge
371 extern VP8LumaFilterFunc VP8VFilter16;
372 extern VP8LumaFilterFunc VP8HFilter16;
373 extern VP8ChromaFilterFunc VP8VFilter8;
374 extern VP8ChromaFilterFunc VP8HFilter8;
375 
376 // on inner edge
377 extern VP8LumaFilterFunc VP8VFilter16i;   // filtering 3 inner edges altogether
378 extern VP8LumaFilterFunc VP8HFilter16i;
379 extern VP8ChromaFilterFunc VP8VFilter8i;  // filtering u and v altogether
380 extern VP8ChromaFilterFunc VP8HFilter8i;
381 
382 // Dithering. Combines dithering values (centered around 128) with dst[],
383 // according to: dst[] = clip(dst[] + (((dither[]-128) + 8) >> 4)
384 #define VP8_DITHER_DESCALE 4
385 #define VP8_DITHER_DESCALE_ROUNDER (1 << (VP8_DITHER_DESCALE - 1))
386 #define VP8_DITHER_AMP_BITS 7
387 #define VP8_DITHER_AMP_CENTER (1 << VP8_DITHER_AMP_BITS)
388 extern void (*VP8DitherCombine8x8)(const uint8_t* dither, uint8_t* dst,
389                                    int dst_stride);
390 
391 // must be called before anything using the above
392 void VP8DspInit(void);
393 
394 //------------------------------------------------------------------------------
395 // WebP I/O
396 
397 #define FANCY_UPSAMPLING   // undefined to remove fancy upsampling support
398 
399 // Convert a pair of y/u/v lines together to the output rgb/a colorspace.
400 // bottom_y can be NULL if only one line of output is needed (at top/bottom).
401 typedef void (*WebPUpsampleLinePairFunc)(
402     const uint8_t* top_y, const uint8_t* bottom_y,
403     const uint8_t* top_u, const uint8_t* top_v,
404     const uint8_t* cur_u, const uint8_t* cur_v,
405     uint8_t* top_dst, uint8_t* bottom_dst, int len);
406 
407 #ifdef FANCY_UPSAMPLING
408 
409 // Fancy upsampling functions to convert YUV to RGB(A) modes
410 extern WebPUpsampleLinePairFunc WebPUpsamplers[/* MODE_LAST */];
411 
412 #endif    // FANCY_UPSAMPLING
413 
414 // Per-row point-sampling methods.
415 typedef void (*WebPSamplerRowFunc)(const uint8_t* y,
416                                    const uint8_t* u, const uint8_t* v,
417                                    uint8_t* dst, int len);
418 // Generic function to apply 'WebPSamplerRowFunc' to the whole plane:
419 void WebPSamplerProcessPlane(const uint8_t* y, int y_stride,
420                              const uint8_t* u, const uint8_t* v, int uv_stride,
421                              uint8_t* dst, int dst_stride,
422                              int width, int height, WebPSamplerRowFunc func);
423 
424 // Sampling functions to convert rows of YUV to RGB(A)
425 extern WebPSamplerRowFunc WebPSamplers[/* MODE_LAST */];
426 
427 // General function for converting two lines of ARGB or RGBA.
428 // 'alpha_is_last' should be true if 0xff000000 is stored in memory as
429 // as 0x00, 0x00, 0x00, 0xff (little endian).
430 WebPUpsampleLinePairFunc WebPGetLinePairConverter(int alpha_is_last);
431 
432 // YUV444->RGB converters
433 typedef void (*WebPYUV444Converter)(const uint8_t* y,
434                                     const uint8_t* u, const uint8_t* v,
435                                     uint8_t* dst, int len);
436 
437 extern WebPYUV444Converter WebPYUV444Converters[/* MODE_LAST */];
438 
439 // Must be called before using the WebPUpsamplers[] (and for premultiplied
440 // colorspaces like rgbA, rgbA4444, etc)
441 void WebPInitUpsamplers(void);
442 // Must be called before using WebPSamplers[]
443 void WebPInitSamplers(void);
444 // Must be called before using WebPYUV444Converters[]
445 void WebPInitYUV444Converters(void);
446 
447 //------------------------------------------------------------------------------
448 // ARGB -> YUV converters
449 
450 // Convert ARGB samples to luma Y.
451 extern void (*WebPConvertARGBToY)(const uint32_t* argb, uint8_t* y, int width);
452 // Convert ARGB samples to U/V with downsampling. do_store should be '1' for
453 // even lines and '0' for odd ones. 'src_width' is the original width, not
454 // the U/V one.
455 extern void (*WebPConvertARGBToUV)(const uint32_t* argb, uint8_t* u, uint8_t* v,
456                                    int src_width, int do_store);
457 
458 // Convert a row of accumulated (four-values) of rgba32 toward U/V
459 extern void (*WebPConvertRGBA32ToUV)(const uint16_t* rgb,
460                                      uint8_t* u, uint8_t* v, int width);
461 
462 // Convert RGB or BGR to Y
463 extern void (*WebPConvertRGB24ToY)(const uint8_t* rgb, uint8_t* y, int width);
464 extern void (*WebPConvertBGR24ToY)(const uint8_t* bgr, uint8_t* y, int width);
465 
466 // used for plain-C fallback.
467 extern void WebPConvertARGBToUV_C(const uint32_t* argb, uint8_t* u, uint8_t* v,
468                                   int src_width, int do_store);
469 extern void WebPConvertRGBA32ToUV_C(const uint16_t* rgb,
470                                     uint8_t* u, uint8_t* v, int width);
471 
472 // utilities for accurate RGB->YUV conversion
473 extern uint64_t (*WebPSharpYUVUpdateY)(const uint16_t* src, const uint16_t* ref,
474                                        uint16_t* dst, int len);
475 extern void (*WebPSharpYUVUpdateRGB)(const int16_t* src, const int16_t* ref,
476                                      int16_t* dst, int len);
477 extern void (*WebPSharpYUVFilterRow)(const int16_t* A, const int16_t* B,
478                                      int len,
479                                      const uint16_t* best_y, uint16_t* out);
480 
481 // Must be called before using the above.
482 void WebPInitConvertARGBToYUV(void);
483 
484 //------------------------------------------------------------------------------
485 // Rescaler
486 
487 struct WebPRescaler;
488 
489 // Import a row of data and save its contribution in the rescaler.
490 // 'channel' denotes the channel number to be imported. 'Expand' corresponds to
491 // the wrk->x_expand case. Otherwise, 'Shrink' is to be used.
492 typedef void (*WebPRescalerImportRowFunc)(struct WebPRescaler* const wrk,
493                                           const uint8_t* src);
494 
495 extern WebPRescalerImportRowFunc WebPRescalerImportRowExpand;
496 extern WebPRescalerImportRowFunc WebPRescalerImportRowShrink;
497 
498 // Export one row (starting at x_out position) from rescaler.
499 // 'Expand' corresponds to the wrk->y_expand case.
500 // Otherwise 'Shrink' is to be used
501 typedef void (*WebPRescalerExportRowFunc)(struct WebPRescaler* const wrk);
502 extern WebPRescalerExportRowFunc WebPRescalerExportRowExpand;
503 extern WebPRescalerExportRowFunc WebPRescalerExportRowShrink;
504 
505 // Plain-C implementation, as fall-back.
506 extern void WebPRescalerImportRowExpand_C(struct WebPRescaler* const wrk,
507                                           const uint8_t* src);
508 extern void WebPRescalerImportRowShrink_C(struct WebPRescaler* const wrk,
509                                           const uint8_t* src);
510 extern void WebPRescalerExportRowExpand_C(struct WebPRescaler* const wrk);
511 extern void WebPRescalerExportRowShrink_C(struct WebPRescaler* const wrk);
512 
513 // Main entry calls:
514 extern void WebPRescalerImportRow(struct WebPRescaler* const wrk,
515                                   const uint8_t* src);
516 // Export one row (starting at x_out position) from rescaler.
517 extern void WebPRescalerExportRow(struct WebPRescaler* const wrk);
518 
519 // Must be called first before using the above.
520 void WebPRescalerDspInit(void);
521 
522 //------------------------------------------------------------------------------
523 // Utilities for processing transparent channel.
524 
525 // Apply alpha pre-multiply on an rgba, bgra or argb plane of size w * h.
526 // alpha_first should be 0 for argb, 1 for rgba or bgra (where alpha is last).
527 extern void (*WebPApplyAlphaMultiply)(
528     uint8_t* rgba, int alpha_first, int w, int h, int stride);
529 
530 // Same, buf specifically for RGBA4444 format
531 extern void (*WebPApplyAlphaMultiply4444)(
532     uint8_t* rgba4444, int w, int h, int stride);
533 
534 // Dispatch the values from alpha[] plane to the ARGB destination 'dst'.
535 // Returns true if alpha[] plane has non-trivial values different from 0xff.
536 extern int (*WebPDispatchAlpha)(const uint8_t* alpha, int alpha_stride,
537                                 int width, int height,
538                                 uint8_t* dst, int dst_stride);
539 
540 // Transfer packed 8b alpha[] values to green channel in dst[], zero'ing the
541 // A/R/B values. 'dst_stride' is the stride for dst[] in uint32_t units.
542 extern void (*WebPDispatchAlphaToGreen)(const uint8_t* alpha, int alpha_stride,
543                                         int width, int height,
544                                         uint32_t* dst, int dst_stride);
545 
546 // Extract the alpha values from 32b values in argb[] and pack them into alpha[]
547 // (this is the opposite of WebPDispatchAlpha).
548 // Returns true if there's only trivial 0xff alpha values.
549 extern int (*WebPExtractAlpha)(const uint8_t* argb, int argb_stride,
550                                int width, int height,
551                                uint8_t* alpha, int alpha_stride);
552 
553 // Extract the green values from 32b values in argb[] and pack them into alpha[]
554 // (this is the opposite of WebPDispatchAlphaToGreen).
555 extern void (*WebPExtractGreen)(const uint32_t* argb, uint8_t* alpha, int size);
556 
557 // Pre-Multiply operation transforms x into x * A / 255  (where x=Y,R,G or B).
558 // Un-Multiply operation transforms x into x * 255 / A.
559 
560 // Pre-Multiply or Un-Multiply (if 'inverse' is true) argb values in a row.
561 extern void (*WebPMultARGBRow)(uint32_t* const ptr, int width, int inverse);
562 
563 // Same a WebPMultARGBRow(), but for several rows.
564 void WebPMultARGBRows(uint8_t* ptr, int stride, int width, int num_rows,
565                       int inverse);
566 
567 // Same for a row of single values, with side alpha values.
568 extern void (*WebPMultRow)(uint8_t* const ptr, const uint8_t* const alpha,
569                            int width, int inverse);
570 
571 // Same a WebPMultRow(), but for several 'num_rows' rows.
572 void WebPMultRows(uint8_t* ptr, int stride,
573                   const uint8_t* alpha, int alpha_stride,
574                   int width, int num_rows, int inverse);
575 
576 // Plain-C versions, used as fallback by some implementations.
577 void WebPMultRow_C(uint8_t* const ptr, const uint8_t* const alpha,
578                    int width, int inverse);
579 void WebPMultARGBRow_C(uint32_t* const ptr, int width, int inverse);
580 
581 // RGB packing function. 'step' can be 3 or 4. r/g/b input is rgb or bgr order.
582 extern void (*WebPPackRGB)(const uint8_t* r, const uint8_t* g, const uint8_t* b,
583                            int len, int step, uint32_t* out);
584 
585 // This function returns true if src[i] contains a value different from 0xff.
586 extern int (*WebPHasAlpha8b)(const uint8_t* src, int length);
587 // This function returns true if src[4*i] contains a value different from 0xff.
588 extern int (*WebPHasAlpha32b)(const uint8_t* src, int length);
589 
590 // To be called first before using the above.
591 void WebPInitAlphaProcessing(void);
592 
593 //------------------------------------------------------------------------------
594 // Filter functions
595 
596 typedef enum {     // Filter types.
597   WEBP_FILTER_NONE = 0,
598   WEBP_FILTER_HORIZONTAL,
599   WEBP_FILTER_VERTICAL,
600   WEBP_FILTER_GRADIENT,
601   WEBP_FILTER_LAST = WEBP_FILTER_GRADIENT + 1,  // end marker
602   WEBP_FILTER_BEST,    // meta-types
603   WEBP_FILTER_FAST
604 } WEBP_FILTER_TYPE;
605 
606 typedef void (*WebPFilterFunc)(const uint8_t* in, int width, int height,
607                                int stride, uint8_t* out);
608 // In-place un-filtering.
609 // Warning! 'prev_line' pointer can be equal to 'cur_line' or 'preds'.
610 typedef void (*WebPUnfilterFunc)(const uint8_t* prev_line, const uint8_t* preds,
611                                  uint8_t* cur_line, int width);
612 
613 // Filter the given data using the given predictor.
614 // 'in' corresponds to a 2-dimensional pixel array of size (stride * height)
615 // in raster order.
616 // 'stride' is number of bytes per scan line (with possible padding).
617 // 'out' should be pre-allocated.
618 extern WebPFilterFunc WebPFilters[WEBP_FILTER_LAST];
619 
620 // In-place reconstruct the original data from the given filtered data.
621 // The reconstruction will be done for 'num_rows' rows starting from 'row'
622 // (assuming rows upto 'row - 1' are already reconstructed).
623 extern WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST];
624 
625 // To be called first before using the above.
626 void VP8FiltersInit(void);
627 
628 #ifdef __cplusplus
629 }    // extern "C"
630 #endif
631 
632 #endif  /* WEBP_DSP_DSP_H_ */
633