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      1 // Copyright 2014 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 // NEON variant of methods for lossless decoder
     11 //
     12 // Author: Skal (pascal.massimino (at) gmail.com)
     13 
     14 #include "./dsp.h"
     15 
     16 #if defined(WEBP_USE_NEON)
     17 
     18 #include <arm_neon.h>
     19 
     20 #include "./lossless.h"
     21 #include "./neon.h"
     22 
     23 //------------------------------------------------------------------------------
     24 // Colorspace conversion functions
     25 
     26 #if !defined(WORK_AROUND_GCC)
     27 // gcc 4.6.0 had some trouble (NDK-r9) with this code. We only use it for
     28 // gcc-4.8.x at least.
     29 static void ConvertBGRAToRGBA(const uint32_t* src,
     30                               int num_pixels, uint8_t* dst) {
     31   const uint32_t* const end = src + (num_pixels & ~15);
     32   for (; src < end; src += 16) {
     33     uint8x16x4_t pixel = vld4q_u8((uint8_t*)src);
     34     // swap B and R. (VSWP d0,d2 has no intrinsics equivalent!)
     35     const uint8x16_t tmp = pixel.val[0];
     36     pixel.val[0] = pixel.val[2];
     37     pixel.val[2] = tmp;
     38     vst4q_u8(dst, pixel);
     39     dst += 64;
     40   }
     41   VP8LConvertBGRAToRGBA_C(src, num_pixels & 15, dst);  // left-overs
     42 }
     43 
     44 static void ConvertBGRAToBGR(const uint32_t* src,
     45                              int num_pixels, uint8_t* dst) {
     46   const uint32_t* const end = src + (num_pixels & ~15);
     47   for (; src < end; src += 16) {
     48     const uint8x16x4_t pixel = vld4q_u8((uint8_t*)src);
     49     const uint8x16x3_t tmp = { { pixel.val[0], pixel.val[1], pixel.val[2] } };
     50     vst3q_u8(dst, tmp);
     51     dst += 48;
     52   }
     53   VP8LConvertBGRAToBGR_C(src, num_pixels & 15, dst);  // left-overs
     54 }
     55 
     56 static void ConvertBGRAToRGB(const uint32_t* src,
     57                              int num_pixels, uint8_t* dst) {
     58   const uint32_t* const end = src + (num_pixels & ~15);
     59   for (; src < end; src += 16) {
     60     const uint8x16x4_t pixel = vld4q_u8((uint8_t*)src);
     61     const uint8x16x3_t tmp = { { pixel.val[2], pixel.val[1], pixel.val[0] } };
     62     vst3q_u8(dst, tmp);
     63     dst += 48;
     64   }
     65   VP8LConvertBGRAToRGB_C(src, num_pixels & 15, dst);  // left-overs
     66 }
     67 
     68 #else  // WORK_AROUND_GCC
     69 
     70 // gcc-4.6.0 fallback
     71 
     72 static const uint8_t kRGBAShuffle[8] = { 2, 1, 0, 3, 6, 5, 4, 7 };
     73 
     74 static void ConvertBGRAToRGBA(const uint32_t* src,
     75                               int num_pixels, uint8_t* dst) {
     76   const uint32_t* const end = src + (num_pixels & ~1);
     77   const uint8x8_t shuffle = vld1_u8(kRGBAShuffle);
     78   for (; src < end; src += 2) {
     79     const uint8x8_t pixels = vld1_u8((uint8_t*)src);
     80     vst1_u8(dst, vtbl1_u8(pixels, shuffle));
     81     dst += 8;
     82   }
     83   VP8LConvertBGRAToRGBA_C(src, num_pixels & 1, dst);  // left-overs
     84 }
     85 
     86 static const uint8_t kBGRShuffle[3][8] = {
     87   {  0,  1,  2,  4,  5,  6,  8,  9 },
     88   { 10, 12, 13, 14, 16, 17, 18, 20 },
     89   { 21, 22, 24, 25, 26, 28, 29, 30 }
     90 };
     91 
     92 static void ConvertBGRAToBGR(const uint32_t* src,
     93                              int num_pixels, uint8_t* dst) {
     94   const uint32_t* const end = src + (num_pixels & ~7);
     95   const uint8x8_t shuffle0 = vld1_u8(kBGRShuffle[0]);
     96   const uint8x8_t shuffle1 = vld1_u8(kBGRShuffle[1]);
     97   const uint8x8_t shuffle2 = vld1_u8(kBGRShuffle[2]);
     98   for (; src < end; src += 8) {
     99     uint8x8x4_t pixels;
    100     INIT_VECTOR4(pixels,
    101                  vld1_u8((const uint8_t*)(src + 0)),
    102                  vld1_u8((const uint8_t*)(src + 2)),
    103                  vld1_u8((const uint8_t*)(src + 4)),
    104                  vld1_u8((const uint8_t*)(src + 6)));
    105     vst1_u8(dst +  0, vtbl4_u8(pixels, shuffle0));
    106     vst1_u8(dst +  8, vtbl4_u8(pixels, shuffle1));
    107     vst1_u8(dst + 16, vtbl4_u8(pixels, shuffle2));
    108     dst += 8 * 3;
    109   }
    110   VP8LConvertBGRAToBGR_C(src, num_pixels & 7, dst);  // left-overs
    111 }
    112 
    113 static const uint8_t kRGBShuffle[3][8] = {
    114   {  2,  1,  0,  6,  5,  4, 10,  9 },
    115   {  8, 14, 13, 12, 18, 17, 16, 22 },
    116   { 21, 20, 26, 25, 24, 30, 29, 28 }
    117 };
    118 
    119 static void ConvertBGRAToRGB(const uint32_t* src,
    120                              int num_pixels, uint8_t* dst) {
    121   const uint32_t* const end = src + (num_pixels & ~7);
    122   const uint8x8_t shuffle0 = vld1_u8(kRGBShuffle[0]);
    123   const uint8x8_t shuffle1 = vld1_u8(kRGBShuffle[1]);
    124   const uint8x8_t shuffle2 = vld1_u8(kRGBShuffle[2]);
    125   for (; src < end; src += 8) {
    126     uint8x8x4_t pixels;
    127     INIT_VECTOR4(pixels,
    128                  vld1_u8((const uint8_t*)(src + 0)),
    129                  vld1_u8((const uint8_t*)(src + 2)),
    130                  vld1_u8((const uint8_t*)(src + 4)),
    131                  vld1_u8((const uint8_t*)(src + 6)));
    132     vst1_u8(dst +  0, vtbl4_u8(pixels, shuffle0));
    133     vst1_u8(dst +  8, vtbl4_u8(pixels, shuffle1));
    134     vst1_u8(dst + 16, vtbl4_u8(pixels, shuffle2));
    135     dst += 8 * 3;
    136   }
    137   VP8LConvertBGRAToRGB_C(src, num_pixels & 7, dst);  // left-overs
    138 }
    139 
    140 #endif   // !WORK_AROUND_GCC
    141 
    142 //------------------------------------------------------------------------------
    143 
    144 #ifdef USE_INTRINSICS
    145 
    146 static WEBP_INLINE uint32_t Average2(const uint32_t* const a,
    147                                      const uint32_t* const b) {
    148   const uint8x8_t a0 = vreinterpret_u8_u64(vcreate_u64(*a));
    149   const uint8x8_t b0 = vreinterpret_u8_u64(vcreate_u64(*b));
    150   const uint8x8_t avg = vhadd_u8(a0, b0);
    151   return vget_lane_u32(vreinterpret_u32_u8(avg), 0);
    152 }
    153 
    154 static WEBP_INLINE uint32_t Average3(const uint32_t* const a,
    155                                      const uint32_t* const b,
    156                                      const uint32_t* const c) {
    157   const uint8x8_t a0 = vreinterpret_u8_u64(vcreate_u64(*a));
    158   const uint8x8_t b0 = vreinterpret_u8_u64(vcreate_u64(*b));
    159   const uint8x8_t c0 = vreinterpret_u8_u64(vcreate_u64(*c));
    160   const uint8x8_t avg1 = vhadd_u8(a0, c0);
    161   const uint8x8_t avg2 = vhadd_u8(avg1, b0);
    162   return vget_lane_u32(vreinterpret_u32_u8(avg2), 0);
    163 }
    164 
    165 static WEBP_INLINE uint32_t Average4(const uint32_t* const a,
    166                                      const uint32_t* const b,
    167                                      const uint32_t* const c,
    168                                      const uint32_t* const d) {
    169   const uint8x8_t a0 = vreinterpret_u8_u64(vcreate_u64(*a));
    170   const uint8x8_t b0 = vreinterpret_u8_u64(vcreate_u64(*b));
    171   const uint8x8_t c0 = vreinterpret_u8_u64(vcreate_u64(*c));
    172   const uint8x8_t d0 = vreinterpret_u8_u64(vcreate_u64(*d));
    173   const uint8x8_t avg1 = vhadd_u8(a0, b0);
    174   const uint8x8_t avg2 = vhadd_u8(c0, d0);
    175   const uint8x8_t avg3 = vhadd_u8(avg1, avg2);
    176   return vget_lane_u32(vreinterpret_u32_u8(avg3), 0);
    177 }
    178 
    179 static uint32_t Predictor5(uint32_t left, const uint32_t* const top) {
    180   return Average3(&left, top + 0, top + 1);
    181 }
    182 
    183 static uint32_t Predictor6(uint32_t left, const uint32_t* const top) {
    184   return Average2(&left, top - 1);
    185 }
    186 
    187 static uint32_t Predictor7(uint32_t left, const uint32_t* const top) {
    188   return Average2(&left, top + 0);
    189 }
    190 
    191 static uint32_t Predictor8(uint32_t left, const uint32_t* const top) {
    192   (void)left;
    193   return Average2(top - 1, top + 0);
    194 }
    195 
    196 static uint32_t Predictor9(uint32_t left, const uint32_t* const top) {
    197   (void)left;
    198   return Average2(top + 0, top + 1);
    199 }
    200 
    201 static uint32_t Predictor10(uint32_t left, const uint32_t* const top) {
    202   return Average4(&left, top - 1, top + 0, top + 1);
    203 }
    204 
    205 //------------------------------------------------------------------------------
    206 
    207 static WEBP_INLINE uint32_t Select(const uint32_t* const c0,
    208                                    const uint32_t* const c1,
    209                                    const uint32_t* const c2) {
    210   const uint8x8_t p0 = vreinterpret_u8_u64(vcreate_u64(*c0));
    211   const uint8x8_t p1 = vreinterpret_u8_u64(vcreate_u64(*c1));
    212   const uint8x8_t p2 = vreinterpret_u8_u64(vcreate_u64(*c2));
    213   const uint8x8_t bc = vabd_u8(p1, p2);   // |b-c|
    214   const uint8x8_t ac = vabd_u8(p0, p2);   // |a-c|
    215   const int16x4_t sum_bc = vreinterpret_s16_u16(vpaddl_u8(bc));
    216   const int16x4_t sum_ac = vreinterpret_s16_u16(vpaddl_u8(ac));
    217   const int32x2_t diff = vpaddl_s16(vsub_s16(sum_bc, sum_ac));
    218   const int32_t pa_minus_pb = vget_lane_s32(diff, 0);
    219   return (pa_minus_pb <= 0) ? *c0 : *c1;
    220 }
    221 
    222 static uint32_t Predictor11(uint32_t left, const uint32_t* const top) {
    223   return Select(top + 0, &left, top - 1);
    224 }
    225 
    226 static WEBP_INLINE uint32_t ClampedAddSubtractFull(const uint32_t* const c0,
    227                                                    const uint32_t* const c1,
    228                                                    const uint32_t* const c2) {
    229   const uint8x8_t p0 = vreinterpret_u8_u64(vcreate_u64(*c0));
    230   const uint8x8_t p1 = vreinterpret_u8_u64(vcreate_u64(*c1));
    231   const uint8x8_t p2 = vreinterpret_u8_u64(vcreate_u64(*c2));
    232   const uint16x8_t sum0 = vaddl_u8(p0, p1);                // add and widen
    233   const uint16x8_t sum1 = vqsubq_u16(sum0, vmovl_u8(p2));  // widen and subtract
    234   const uint8x8_t out = vqmovn_u16(sum1);                  // narrow and clamp
    235   return vget_lane_u32(vreinterpret_u32_u8(out), 0);
    236 }
    237 
    238 static uint32_t Predictor12(uint32_t left, const uint32_t* const top) {
    239   return ClampedAddSubtractFull(&left, top + 0, top - 1);
    240 }
    241 
    242 static WEBP_INLINE uint32_t ClampedAddSubtractHalf(const uint32_t* const c0,
    243                                                    const uint32_t* const c1,
    244                                                    const uint32_t* const c2) {
    245   const uint8x8_t p0 = vreinterpret_u8_u64(vcreate_u64(*c0));
    246   const uint8x8_t p1 = vreinterpret_u8_u64(vcreate_u64(*c1));
    247   const uint8x8_t p2 = vreinterpret_u8_u64(vcreate_u64(*c2));
    248   const uint8x8_t avg = vhadd_u8(p0, p1);                  // Average(c0,c1)
    249   const uint8x8_t ab = vshr_n_u8(vqsub_u8(avg, p2), 1);    // (a-b)>>1 saturated
    250   const uint8x8_t ba = vshr_n_u8(vqsub_u8(p2, avg), 1);    // (b-a)>>1 saturated
    251   const uint8x8_t out = vqsub_u8(vqadd_u8(avg, ab), ba);
    252   return vget_lane_u32(vreinterpret_u32_u8(out), 0);
    253 }
    254 
    255 static uint32_t Predictor13(uint32_t left, const uint32_t* const top) {
    256   return ClampedAddSubtractHalf(&left, top + 0, top - 1);
    257 }
    258 
    259 //------------------------------------------------------------------------------
    260 // Subtract-Green Transform
    261 
    262 // vtbl?_u8 are marked unavailable for iOS arm64 with Xcode < 6.3, use
    263 // non-standard versions there.
    264 #if defined(__APPLE__) && defined(__aarch64__) && \
    265     defined(__apple_build_version__) && (__apple_build_version__< 6020037)
    266 #define USE_VTBLQ
    267 #endif
    268 
    269 #ifdef USE_VTBLQ
    270 // 255 = byte will be zeroed
    271 static const uint8_t kGreenShuffle[16] = {
    272   1, 255, 1, 255, 5, 255, 5, 255, 9, 255, 9, 255, 13, 255, 13, 255
    273 };
    274 
    275 static WEBP_INLINE uint8x16_t DoGreenShuffle(const uint8x16_t argb,
    276                                              const uint8x16_t shuffle) {
    277   return vcombine_u8(vtbl1q_u8(argb, vget_low_u8(shuffle)),
    278                      vtbl1q_u8(argb, vget_high_u8(shuffle)));
    279 }
    280 #else  // !USE_VTBLQ
    281 // 255 = byte will be zeroed
    282 static const uint8_t kGreenShuffle[8] = { 1, 255, 1, 255, 5, 255, 5, 255  };
    283 
    284 static WEBP_INLINE uint8x16_t DoGreenShuffle(const uint8x16_t argb,
    285                                              const uint8x8_t shuffle) {
    286   return vcombine_u8(vtbl1_u8(vget_low_u8(argb), shuffle),
    287                      vtbl1_u8(vget_high_u8(argb), shuffle));
    288 }
    289 #endif  // USE_VTBLQ
    290 
    291 static void SubtractGreenFromBlueAndRed(uint32_t* argb_data, int num_pixels) {
    292   const uint32_t* const end = argb_data + (num_pixels & ~3);
    293 #ifdef USE_VTBLQ
    294   const uint8x16_t shuffle = vld1q_u8(kGreenShuffle);
    295 #else
    296   const uint8x8_t shuffle = vld1_u8(kGreenShuffle);
    297 #endif
    298   for (; argb_data < end; argb_data += 4) {
    299     const uint8x16_t argb = vld1q_u8((uint8_t*)argb_data);
    300     const uint8x16_t greens = DoGreenShuffle(argb, shuffle);
    301     vst1q_u8((uint8_t*)argb_data, vsubq_u8(argb, greens));
    302   }
    303   // fallthrough and finish off with plain-C
    304   VP8LSubtractGreenFromBlueAndRed_C(argb_data, num_pixels & 3);
    305 }
    306 
    307 static void AddGreenToBlueAndRed(uint32_t* argb_data, int num_pixels) {
    308   const uint32_t* const end = argb_data + (num_pixels & ~3);
    309 #ifdef USE_VTBLQ
    310   const uint8x16_t shuffle = vld1q_u8(kGreenShuffle);
    311 #else
    312   const uint8x8_t shuffle = vld1_u8(kGreenShuffle);
    313 #endif
    314   for (; argb_data < end; argb_data += 4) {
    315     const uint8x16_t argb = vld1q_u8((uint8_t*)argb_data);
    316     const uint8x16_t greens = DoGreenShuffle(argb, shuffle);
    317     vst1q_u8((uint8_t*)argb_data, vaddq_u8(argb, greens));
    318   }
    319   // fallthrough and finish off with plain-C
    320   VP8LAddGreenToBlueAndRed_C(argb_data, num_pixels & 3);
    321 }
    322 
    323 #undef USE_VTBLQ
    324 
    325 #endif   // USE_INTRINSICS
    326 
    327 #endif   // WEBP_USE_NEON
    328 
    329 //------------------------------------------------------------------------------
    330 
    331 extern void VP8LDspInitNEON(void);
    332 
    333 void VP8LDspInitNEON(void) {
    334 #if defined(WEBP_USE_NEON)
    335   VP8LConvertBGRAToRGBA = ConvertBGRAToRGBA;
    336   VP8LConvertBGRAToBGR = ConvertBGRAToBGR;
    337   VP8LConvertBGRAToRGB = ConvertBGRAToRGB;
    338 
    339 #ifdef USE_INTRINSICS
    340   VP8LPredictors[5] = Predictor5;
    341   VP8LPredictors[6] = Predictor6;
    342   VP8LPredictors[7] = Predictor7;
    343   VP8LPredictors[8] = Predictor8;
    344   VP8LPredictors[9] = Predictor9;
    345   VP8LPredictors[10] = Predictor10;
    346   VP8LPredictors[11] = Predictor11;
    347   VP8LPredictors[12] = Predictor12;
    348   VP8LPredictors[13] = Predictor13;
    349 
    350   VP8LSubtractGreenFromBlueAndRed = SubtractGreenFromBlueAndRed;
    351   VP8LAddGreenToBlueAndRed = AddGreenToBlueAndRed;
    352 #endif
    353 
    354 #endif   // WEBP_USE_NEON
    355 }
    356 
    357 //------------------------------------------------------------------------------
    358