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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 // SSE2 version of YUV to RGB upsampling functions.
     11 //
     12 // Author: somnath (at) google.com (Somnath Banerjee)
     13 
     14 #include "./dsp.h"
     15 
     16 #if defined(WEBP_USE_SSE2)
     17 
     18 #include <assert.h>
     19 #include <emmintrin.h>
     20 #include <string.h>
     21 #include "./yuv.h"
     22 
     23 #ifdef FANCY_UPSAMPLING
     24 
     25 // We compute (9*a + 3*b + 3*c + d + 8) / 16 as follows
     26 // u = (9*a + 3*b + 3*c + d + 8) / 16
     27 //   = (a + (a + 3*b + 3*c + d) / 8 + 1) / 2
     28 //   = (a + m + 1) / 2
     29 // where m = (a + 3*b + 3*c + d) / 8
     30 //         = ((a + b + c + d) / 2 + b + c) / 4
     31 //
     32 // Let's say  k = (a + b + c + d) / 4.
     33 // We can compute k as
     34 // k = (s + t + 1) / 2 - ((a^d) | (b^c) | (s^t)) & 1
     35 // where s = (a + d + 1) / 2 and t = (b + c + 1) / 2
     36 //
     37 // Then m can be written as
     38 // m = (k + t + 1) / 2 - (((b^c) & (s^t)) | (k^t)) & 1
     39 
     40 // Computes out = (k + in + 1) / 2 - ((ij & (s^t)) | (k^in)) & 1
     41 #define GET_M(ij, in, out) do {                                                \
     42   const __m128i tmp0 = _mm_avg_epu8(k, (in));     /* (k + in + 1) / 2 */       \
     43   const __m128i tmp1 = _mm_and_si128((ij), st);   /* (ij) & (s^t) */           \
     44   const __m128i tmp2 = _mm_xor_si128(k, (in));    /* (k^in) */                 \
     45   const __m128i tmp3 = _mm_or_si128(tmp1, tmp2);  /* ((ij) & (s^t)) | (k^in) */\
     46   const __m128i tmp4 = _mm_and_si128(tmp3, one);  /* & 1 -> lsb_correction */  \
     47   (out) = _mm_sub_epi8(tmp0, tmp4);    /* (k + in + 1) / 2 - lsb_correction */ \
     48 } while (0)
     49 
     50 // pack and store two alternating pixel rows
     51 #define PACK_AND_STORE(a, b, da, db, out) do {                                 \
     52   const __m128i t_a = _mm_avg_epu8(a, da);  /* (9a + 3b + 3c +  d + 8) / 16 */ \
     53   const __m128i t_b = _mm_avg_epu8(b, db);  /* (3a + 9b +  c + 3d + 8) / 16 */ \
     54   const __m128i t_1 = _mm_unpacklo_epi8(t_a, t_b);                             \
     55   const __m128i t_2 = _mm_unpackhi_epi8(t_a, t_b);                             \
     56   _mm_store_si128(((__m128i*)(out)) + 0, t_1);                                 \
     57   _mm_store_si128(((__m128i*)(out)) + 1, t_2);                                 \
     58 } while (0)
     59 
     60 // Loads 17 pixels each from rows r1 and r2 and generates 32 pixels.
     61 #define UPSAMPLE_32PIXELS(r1, r2, out) {                                       \
     62   const __m128i one = _mm_set1_epi8(1);                                        \
     63   const __m128i a = _mm_loadu_si128((__m128i*)&(r1)[0]);                       \
     64   const __m128i b = _mm_loadu_si128((__m128i*)&(r1)[1]);                       \
     65   const __m128i c = _mm_loadu_si128((__m128i*)&(r2)[0]);                       \
     66   const __m128i d = _mm_loadu_si128((__m128i*)&(r2)[1]);                       \
     67                                                                                \
     68   const __m128i s = _mm_avg_epu8(a, d);        /* s = (a + d + 1) / 2 */       \
     69   const __m128i t = _mm_avg_epu8(b, c);        /* t = (b + c + 1) / 2 */       \
     70   const __m128i st = _mm_xor_si128(s, t);      /* st = s^t */                  \
     71                                                                                \
     72   const __m128i ad = _mm_xor_si128(a, d);      /* ad = a^d */                  \
     73   const __m128i bc = _mm_xor_si128(b, c);      /* bc = b^c */                  \
     74                                                                                \
     75   const __m128i t1 = _mm_or_si128(ad, bc);     /* (a^d) | (b^c) */             \
     76   const __m128i t2 = _mm_or_si128(t1, st);     /* (a^d) | (b^c) | (s^t) */     \
     77   const __m128i t3 = _mm_and_si128(t2, one);   /* (a^d) | (b^c) | (s^t) & 1 */ \
     78   const __m128i t4 = _mm_avg_epu8(s, t);                                       \
     79   const __m128i k = _mm_sub_epi8(t4, t3);      /* k = (a + b + c + d) / 4 */   \
     80   __m128i diag1, diag2;                                                        \
     81                                                                                \
     82   GET_M(bc, t, diag1);                  /* diag1 = (a + 3b + 3c + d) / 8 */    \
     83   GET_M(ad, s, diag2);                  /* diag2 = (3a + b + c + 3d) / 8 */    \
     84                                                                                \
     85   /* pack the alternate pixels */                                              \
     86   PACK_AND_STORE(a, b, diag1, diag2, out +      0);  /* store top */           \
     87   PACK_AND_STORE(c, d, diag2, diag1, out + 2 * 32);  /* store bottom */        \
     88 }
     89 
     90 // Turn the macro into a function for reducing code-size when non-critical
     91 static void Upsample32Pixels(const uint8_t r1[], const uint8_t r2[],
     92                              uint8_t* const out) {
     93   UPSAMPLE_32PIXELS(r1, r2, out);
     94 }
     95 
     96 #define UPSAMPLE_LAST_BLOCK(tb, bb, num_pixels, out) {                         \
     97   uint8_t r1[17], r2[17];                                                      \
     98   memcpy(r1, (tb), (num_pixels));                                              \
     99   memcpy(r2, (bb), (num_pixels));                                              \
    100   /* replicate last byte */                                                    \
    101   memset(r1 + (num_pixels), r1[(num_pixels) - 1], 17 - (num_pixels));          \
    102   memset(r2 + (num_pixels), r2[(num_pixels) - 1], 17 - (num_pixels));          \
    103   /* using the shared function instead of the macro saves ~3k code size */     \
    104   Upsample32Pixels(r1, r2, out);                                               \
    105 }
    106 
    107 #define CONVERT2RGB(FUNC, XSTEP, top_y, bottom_y,                              \
    108                     top_dst, bottom_dst, cur_x, num_pixels) {                  \
    109   int n;                                                                       \
    110   for (n = 0; n < (num_pixels); ++n) {                                         \
    111     FUNC(top_y[(cur_x) + n], r_u[n], r_v[n],                                   \
    112          top_dst + ((cur_x) + n) * XSTEP);                                     \
    113   }                                                                            \
    114   if (bottom_y != NULL) {                                                      \
    115     for (n = 0; n < (num_pixels); ++n) {                                       \
    116       FUNC(bottom_y[(cur_x) + n], r_u[64 + n], r_v[64 + n],                    \
    117            bottom_dst + ((cur_x) + n) * XSTEP);                                \
    118     }                                                                          \
    119   }                                                                            \
    120 }
    121 
    122 #define CONVERT2RGB_32(FUNC, XSTEP, top_y, bottom_y,                           \
    123                        top_dst, bottom_dst, cur_x) do {                        \
    124   FUNC##32(top_y + (cur_x), r_u, r_v, top_dst + (cur_x) * XSTEP);              \
    125   if (bottom_y != NULL) {                                                      \
    126     FUNC##32(bottom_y + (cur_x), r_u + 64, r_v + 64,                           \
    127              bottom_dst + (cur_x) * XSTEP);                                    \
    128   }                                                                            \
    129 } while (0)
    130 
    131 #define SSE2_UPSAMPLE_FUNC(FUNC_NAME, FUNC, XSTEP)                             \
    132 static void FUNC_NAME(const uint8_t* top_y, const uint8_t* bottom_y,           \
    133                       const uint8_t* top_u, const uint8_t* top_v,              \
    134                       const uint8_t* cur_u, const uint8_t* cur_v,              \
    135                       uint8_t* top_dst, uint8_t* bottom_dst, int len) {        \
    136   int uv_pos, pos;                                                             \
    137   /* 16byte-aligned array to cache reconstructed u and v */                    \
    138   uint8_t uv_buf[4 * 32 + 15];                                                 \
    139   uint8_t* const r_u = (uint8_t*)((uintptr_t)(uv_buf + 15) & ~15);             \
    140   uint8_t* const r_v = r_u + 32;                                               \
    141                                                                                \
    142   assert(top_y != NULL);                                                       \
    143   {   /* Treat the first pixel in regular way */                               \
    144     const int u_diag = ((top_u[0] + cur_u[0]) >> 1) + 1;                       \
    145     const int v_diag = ((top_v[0] + cur_v[0]) >> 1) + 1;                       \
    146     const int u0_t = (top_u[0] + u_diag) >> 1;                                 \
    147     const int v0_t = (top_v[0] + v_diag) >> 1;                                 \
    148     FUNC(top_y[0], u0_t, v0_t, top_dst);                                       \
    149     if (bottom_y != NULL) {                                                    \
    150       const int u0_b = (cur_u[0] + u_diag) >> 1;                               \
    151       const int v0_b = (cur_v[0] + v_diag) >> 1;                               \
    152       FUNC(bottom_y[0], u0_b, v0_b, bottom_dst);                               \
    153     }                                                                          \
    154   }                                                                            \
    155   /* For UPSAMPLE_32PIXELS, 17 u/v values must be read-able for each block */  \
    156   for (pos = 1, uv_pos = 0; pos + 32 + 1 <= len; pos += 32, uv_pos += 16) {    \
    157     UPSAMPLE_32PIXELS(top_u + uv_pos, cur_u + uv_pos, r_u);                    \
    158     UPSAMPLE_32PIXELS(top_v + uv_pos, cur_v + uv_pos, r_v);                    \
    159     CONVERT2RGB_32(FUNC, XSTEP, top_y, bottom_y, top_dst, bottom_dst, pos);    \
    160   }                                                                            \
    161   if (len > 1) {                                                               \
    162     const int left_over = ((len + 1) >> 1) - (pos >> 1);                       \
    163     assert(left_over > 0);                                                     \
    164     UPSAMPLE_LAST_BLOCK(top_u + uv_pos, cur_u + uv_pos, left_over, r_u);       \
    165     UPSAMPLE_LAST_BLOCK(top_v + uv_pos, cur_v + uv_pos, left_over, r_v);       \
    166     CONVERT2RGB(FUNC, XSTEP, top_y, bottom_y, top_dst, bottom_dst,             \
    167                 pos, len - pos);                                               \
    168   }                                                                            \
    169 }
    170 
    171 // SSE2 variants of the fancy upsampler.
    172 SSE2_UPSAMPLE_FUNC(UpsampleRgbLinePair,  VP8YuvToRgb,  3)
    173 SSE2_UPSAMPLE_FUNC(UpsampleBgrLinePair,  VP8YuvToBgr,  3)
    174 SSE2_UPSAMPLE_FUNC(UpsampleRgbaLinePair, VP8YuvToRgba, 4)
    175 SSE2_UPSAMPLE_FUNC(UpsampleBgraLinePair, VP8YuvToBgra, 4)
    176 
    177 #undef GET_M
    178 #undef PACK_AND_STORE
    179 #undef UPSAMPLE_32PIXELS
    180 #undef UPSAMPLE_LAST_BLOCK
    181 #undef CONVERT2RGB
    182 #undef CONVERT2RGB_32
    183 #undef SSE2_UPSAMPLE_FUNC
    184 
    185 #endif  // FANCY_UPSAMPLING
    186 
    187 #endif   // WEBP_USE_SSE2
    188 
    189 //------------------------------------------------------------------------------
    190 
    191 extern void WebPInitUpsamplersSSE2(void);
    192 
    193 #ifdef FANCY_UPSAMPLING
    194 
    195 extern WebPUpsampleLinePairFunc WebPUpsamplers[/* MODE_LAST */];
    196 
    197 void WebPInitUpsamplersSSE2(void) {
    198 #if defined(WEBP_USE_SSE2)
    199   VP8YUVInitSSE2();
    200   WebPUpsamplers[MODE_RGB]  = UpsampleRgbLinePair;
    201   WebPUpsamplers[MODE_RGBA] = UpsampleRgbaLinePair;
    202   WebPUpsamplers[MODE_BGR]  = UpsampleBgrLinePair;
    203   WebPUpsamplers[MODE_BGRA] = UpsampleBgraLinePair;
    204   WebPUpsamplers[MODE_rgbA] = UpsampleRgbaLinePair;
    205   WebPUpsamplers[MODE_bgrA] = UpsampleBgraLinePair;
    206 #endif   // WEBP_USE_SSE2
    207 }
    208 
    209 #else
    210 
    211 // this empty function is to avoid an empty .o
    212 void WebPInitUpsamplersSSE2(void) {}
    213 
    214 #endif  // FANCY_UPSAMPLING
    215