text: // Copyright 2011 Google Inc. All Rights Reserved.
  //
  // Use of this source code is governed by a BSD-style license
  // that can be found in the COPYING file in the root of the source
  // tree. An additional intellectual property rights grant can be found
  // in the file PATENTS. All contributing project authors may
  // be found in the AUTHORS file in the root of the source tree.
  // -----------------------------------------------------------------------------
  //
  // YUV to RGB upsampling functions.
  //
  // Author: somnath@google.com (Somnath Banerjee)
  
  #include "../dsp/dsp.h"
  #include "../dsp/yuv.h"
  
  #include <assert.h>
  
  //------------------------------------------------------------------------------
  // Fancy upsampler
  
  #ifdef FANCY_UPSAMPLING
  
  // Fancy upsampling functions to convert YUV to RGB
  WebPUpsampleLinePairFunc WebPUpsamplers[MODE_LAST];
  
  // Given samples laid out in a square as:
  //  [a b]
  //  [c d]
  // we interpolate u/v as:
  //  ([9*a + 3*b + 3*c +   d    3*a + 9*b + 3*c +   d] + [8 8]) / 16
  //  ([3*a +   b + 9*c + 3*d      a + 3*b + 3*c + 9*d]   [8 8]) / 16
  
  // We process u and v together stashed into 32bit (16bit each).
  #define LOAD_UV(u, v) ((u) | ((v) << 16))
  
  #define UPSAMPLE_FUNC(FUNC_NAME, FUNC, XSTEP)                                  \
  static void FUNC_NAME(const uint8_t* top_y, const uint8_t* bottom_y,           \
                        const uint8_t* top_u, const uint8_t* top_v,              \
                        const uint8_t* cur_u, const uint8_t* cur_v,              \
                        uint8_t* top_dst, uint8_t* bottom_dst, int len) {        \
    int x;                                                                       \
    const int last_pixel_pair = (len - 1) >> 1;                                  \
    uint32_t tl_uv = LOAD_UV(top_u[0], top_v[0]);   /* top-left sample */        \
    uint32_t l_uv  = LOAD_UV(cur_u[0], cur_v[0]);   /* left-sample */            \
    assert(top_y != NULL);                                                       \
    {                                                                            \
      const uint32_t uv0 = (3 * tl_uv + l_uv + 0x00020002u) >> 2;                \
      FUNC(top_y[0], uv0 & 0xff, (uv0 >> 16), top_dst);                          \
    }                                                                            \
    if (bottom_y != NULL) {                                                      \
      const uint32_t uv0 = (3 * l_uv + tl_uv + 0x00020002u) >> 2;                \
      FUNC(bottom_y[0], uv0 & 0xff, (uv0 >> 16), bottom_dst);                    \
    }                                                                            \
    for (x = 1; x <= last_pixel_pair; ++x) {                                     \
      const uint32_t t_uv = LOAD_UV(top_u[x], top_v[x]);  /* top sample */       \
      const uint32_t uv   = LOAD_UV(cur_u[x], cur_v[x]);  /* sample */           \
      /* precompute invariant values associated with first and second diagonals*/\
      const uint32_t avg = tl_uv + t_uv + l_uv + uv + 0x00080008u;               \
      const uint32_t diag_12 = (avg + 2 * (t_uv + l_uv)) >> 3;                   \
      const uint32_t diag_03 = (avg + 2 * (tl_uv + uv)) >> 3;                    \
      {                                                                          \
        const uint32_t uv0 = (diag_12 + tl_uv) >> 1;                             \
        const uint32_t uv1 = (diag_03 + t_uv) >> 1;                              \
        FUNC(top_y[2 * x - 1], uv0 & 0xff, (uv0 >> 16),                          \
             top_dst + (2 * x - 1) * (XSTEP));                                   \
        FUNC(top_y[2 * x - 0], uv1 & 0xff, (uv1 >> 16),                          \
             top_dst + (2 * x - 0) * (XSTEP));                                   \
      }                                                                          \
      if (bottom_y != NULL) {                                                    \
        const uint32_t uv0 = (diag_03 + l_uv) >> 1;                              \
        const uint32_t uv1 = (diag_12 + uv) >> 1;                                \
        FUNC(bottom_y[2 * x - 1], uv0 & 0xff, (uv0 >> 16),                       \
             bottom_dst + (2 * x - 1) * (XSTEP));                                \
        FUNC(bottom_y[2 * x + 0], uv1 & 0xff, (uv1 >> 16),                       \
             bottom_dst + (2 * x + 0) * (XSTEP));                                \
      }                                                                          \
      tl_uv = t_uv;                                                              \
      l_uv = uv;                                                                 \
    }                                                                            \
    if (!(len & 1)) {                                                            \
      {                                                                          \
        const uint32_t uv0 = (3 * tl_uv + l_uv + 0x00020002u) >> 2;              \
        FUNC(top_y[len - 1], uv0 & 0xff, (uv0 >> 16),                            \
             top_dst + (len - 1) * (XSTEP));                                     \
      }                                                                          \
      if (bottom_y != NULL) {                                                    \
        const uint32_t uv0 = (3 * l_uv + tl_uv + 0x00020002u) >> 2;              \
        FUNC(bottom_y[len - 1], uv0 & 0xff, (uv0 >> 16),                         \
             bottom_dst + (len - 1) * (XSTEP));                                  \
      }                                                                          \
    }                                                                            \
  }
  
  // All variants implemented.
  #if !WEBP_NEON_OMIT_C_CODE
  UPSAMPLE_FUNC(UpsampleRgbaLinePair_C, VP8YuvToRgba, 4)
  UPSAMPLE_FUNC(UpsampleBgraLinePair_C, VP8YuvToBgra, 4)
  #if !defined(WEBP_REDUCE_CSP)
  UPSAMPLE_FUNC(UpsampleArgbLinePair_C, VP8YuvToArgb, 4)
  UPSAMPLE_FUNC(UpsampleRgbLinePair_C,  VP8YuvToRgb,  3)
  UPSAMPLE_FUNC(UpsampleBgrLinePair_C,  VP8YuvToBgr,  3)
  UPSAMPLE_FUNC(UpsampleRgba4444LinePair_C, VP8YuvToRgba4444, 2)
  UPSAMPLE_FUNC(UpsampleRgb565LinePair_C,  VP8YuvToRgb565,  2)
  #else
  static void EmptyUpsampleFunc(const uint8_t* top_y, const uint8_t* bottom_y,
                                const uint8_t* top_u, const uint8_t* top_v,
                                const uint8_t* cur_u, const uint8_t* cur_v,
                                uint8_t* top_dst, uint8_t* bottom_dst, int len) {
    (void)top_y;
    (void)bottom_y;
    (void)top_u;
    (void)top_v;
    (void)cur_u;
    (void)cur_v;
    (void)top_dst;
    (void)bottom_dst;
    (void)len;
    assert(0);   // COLORSPACE SUPPORT NOT COMPILED
  }
  #define UpsampleArgbLinePair_C EmptyUpsampleFunc
  #define UpsampleRgbLinePair_C EmptyUpsampleFunc
  #define UpsampleBgrLinePair_C EmptyUpsampleFunc
  #define UpsampleRgba4444LinePair_C EmptyUpsampleFunc
  #define UpsampleRgb565LinePair_C EmptyUpsampleFunc
  #endif   // WEBP_REDUCE_CSP
  
  #endif
  
  #undef LOAD_UV
  #undef UPSAMPLE_FUNC
  
  #endif  // FANCY_UPSAMPLING
  
  //------------------------------------------------------------------------------
  
  #if !defined(FANCY_UPSAMPLING)
  #define DUAL_SAMPLE_FUNC(FUNC_NAME, FUNC)                                      \
  static void FUNC_NAME(const uint8_t* top_y, const uint8_t* bot_y,              \
                        const uint8_t* top_u, const uint8_t* top_v,              \
                        const uint8_t* bot_u, const uint8_t* bot_v,              \
                        uint8_t* top_dst, uint8_t* bot_dst, int len) {           \
    const int half_len = len >> 1;                                               \
    int x;                                                                       \
    assert(top_dst != NULL);                                                     \
    {                                                                            \
      for (x = 0; x < half_len; ++x) {                                           \
        FUNC(top_y[2 * x + 0], top_u[x], top_v[x], top_dst + 8 * x + 0);         \
        FUNC(top_y[2 * x + 1], top_u[x], top_v[x], top_dst + 8 * x + 4);         \
      }                                                                          \
      if (len & 1) FUNC(top_y[2 * x + 0], top_u[x], top_v[x], top_dst + 8 * x);  \
    }                                                                            \
    if (bot_dst != NULL) {                                                       \
      for (x = 0; x < half_len; ++x) {                                           \
        FUNC(bot_y[2 * x + 0], bot_u[x], bot_v[x], bot_dst + 8 * x + 0);         \
        FUNC(bot_y[2 * x + 1], bot_u[x], bot_v[x], bot_dst + 8 * x + 4);         \
      }                                                                          \
      if (len & 1) FUNC(bot_y[2 * x + 0], bot_u[x], bot_v[x], bot_dst + 8 * x);  \
    }                                                                            \
  }
  
  DUAL_SAMPLE_FUNC(DualLineSamplerBGRA, VP8YuvToBgra)
  DUAL_SAMPLE_FUNC(DualLineSamplerARGB, VP8YuvToArgb)
  #undef DUAL_SAMPLE_FUNC
  
  #endif  // !FANCY_UPSAMPLING
  
  WebPUpsampleLinePairFunc WebPGetLinePairConverter(int alpha_is_last) {
    WebPInitUpsamplers();
  #ifdef FANCY_UPSAMPLING
    return WebPUpsamplers[alpha_is_last ? MODE_BGRA : MODE_ARGB];
  #else
    return (alpha_is_last ? DualLineSamplerBGRA : DualLineSamplerARGB);
  #endif
  }
  
  //------------------------------------------------------------------------------
  // YUV444 converter
  
  #define YUV444_FUNC(FUNC_NAME, FUNC, XSTEP)                                    \
  extern void FUNC_NAME(const uint8_t* y, const uint8_t* u, const uint8_t* v,    \
                        uint8_t* dst, int len);                                  \
  void FUNC_NAME(const uint8_t* y, const uint8_t* u, const uint8_t* v,           \
                 uint8_t* dst, int len) {                                        \
    int i;                                                                       \
    for (i = 0; i < len; ++i) FUNC(y[i], u[i], v[i], &dst[i * (XSTEP)]);         \
  }
  
  YUV444_FUNC(WebPYuv444ToRgba_C,     VP8YuvToRgba, 4)
  YUV444_FUNC(WebPYuv444ToBgra_C,     VP8YuvToBgra, 4)
  #if !defined(WEBP_REDUCE_CSP)
  YUV444_FUNC(WebPYuv444ToRgb_C,      VP8YuvToRgb,  3)
  YUV444_FUNC(WebPYuv444ToBgr_C,      VP8YuvToBgr,  3)
  YUV444_FUNC(WebPYuv444ToArgb_C,     VP8YuvToArgb, 4)
  YUV444_FUNC(WebPYuv444ToRgba4444_C, VP8YuvToRgba4444, 2)
  YUV444_FUNC(WebPYuv444ToRgb565_C,   VP8YuvToRgb565, 2)
  #else
  static void EmptyYuv444Func(const uint8_t* y,
                              const uint8_t* u, const uint8_t* v,
                              uint8_t* dst, int len) {
    (void)y;
    (void)u;
    (void)v;
    (void)dst;
    (void)len;
  }
  #define WebPYuv444ToRgb_C EmptyYuv444Func
  #define WebPYuv444ToBgr_C EmptyYuv444Func
  #define WebPYuv444ToArgb_C EmptyYuv444Func
  #define WebPYuv444ToRgba4444_C EmptyYuv444Func
  #define WebPYuv444ToRgb565_C EmptyYuv444Func
  #endif   // WEBP_REDUCE_CSP
  
  #undef YUV444_FUNC
  
  WebPYUV444Converter WebPYUV444Converters[MODE_LAST];
  
  extern void WebPInitYUV444ConvertersMIPSdspR2(void);
  extern void WebPInitYUV444ConvertersSSE2(void);
  extern void WebPInitYUV444ConvertersSSE41(void);
  
  WEBP_DSP_INIT_FUNC(WebPInitYUV444Converters) {
    WebPYUV444Converters[MODE_RGBA]      = WebPYuv444ToRgba_C;
    WebPYUV444Converters[MODE_BGRA]      = WebPYuv444ToBgra_C;
    WebPYUV444Converters[MODE_RGB]       = WebPYuv444ToRgb_C;
    WebPYUV444Converters[MODE_BGR]       = WebPYuv444ToBgr_C;
    WebPYUV444Converters[MODE_ARGB]      = WebPYuv444ToArgb_C;
    WebPYUV444Converters[MODE_RGBA_4444] = WebPYuv444ToRgba4444_C;
    WebPYUV444Converters[MODE_RGB_565]   = WebPYuv444ToRgb565_C;
    WebPYUV444Converters[MODE_rgbA]      = WebPYuv444ToRgba_C;
    WebPYUV444Converters[MODE_bgrA]      = WebPYuv444ToBgra_C;
    WebPYUV444Converters[MODE_Argb]      = WebPYuv444ToArgb_C;
    WebPYUV444Converters[MODE_rgbA_4444] = WebPYuv444ToRgba4444_C;
  
    if (VP8GetCPUInfo != NULL) {
  #if defined(WEBP_USE_SSE2)
      if (VP8GetCPUInfo(kSSE2)) {
        WebPInitYUV444ConvertersSSE2();
      }
  #endif
  #if defined(WEBP_USE_SSE41)
      if (VP8GetCPUInfo(kSSE4_1)) {
        WebPInitYUV444ConvertersSSE41();
      }
  #endif
  #if defined(WEBP_USE_MIPS_DSP_R2)
      if (VP8GetCPUInfo(kMIPSdspR2)) {
        WebPInitYUV444ConvertersMIPSdspR2();
      }
  #endif
    }
  }
  
  //------------------------------------------------------------------------------
  // Main calls
  
  extern void WebPInitUpsamplersSSE2(void);
  extern void WebPInitUpsamplersSSE41(void);
  extern void WebPInitUpsamplersNEON(void);
  extern void WebPInitUpsamplersMIPSdspR2(void);
  extern void WebPInitUpsamplersMSA(void);
  
  WEBP_DSP_INIT_FUNC(WebPInitUpsamplers) {
  #ifdef FANCY_UPSAMPLING
  #if !WEBP_NEON_OMIT_C_CODE
    WebPUpsamplers[MODE_RGBA]      = UpsampleRgbaLinePair_C;
    WebPUpsamplers[MODE_BGRA]      = UpsampleBgraLinePair_C;
    WebPUpsamplers[MODE_rgbA]      = UpsampleRgbaLinePair_C;
    WebPUpsamplers[MODE_bgrA]      = UpsampleBgraLinePair_C;
    WebPUpsamplers[MODE_RGB]       = UpsampleRgbLinePair_C;
    WebPUpsamplers[MODE_BGR]       = UpsampleBgrLinePair_C;
    WebPUpsamplers[MODE_ARGB]      = UpsampleArgbLinePair_C;
    WebPUpsamplers[MODE_RGBA_4444] = UpsampleRgba4444LinePair_C;
    WebPUpsamplers[MODE_RGB_565]   = UpsampleRgb565LinePair_C;
    WebPUpsamplers[MODE_Argb]      = UpsampleArgbLinePair_C;
    WebPUpsamplers[MODE_rgbA_4444] = UpsampleRgba4444LinePair_C;
  #endif
  
    // If defined, use CPUInfo() to overwrite some pointers with faster versions.
    if (VP8GetCPUInfo != NULL) {
  #if defined(WEBP_USE_SSE2)
      if (VP8GetCPUInfo(kSSE2)) {
        WebPInitUpsamplersSSE2();
      }
  #endif
  #if defined(WEBP_USE_SSE41)
      if (VP8GetCPUInfo(kSSE4_1)) {
        WebPInitUpsamplersSSE41();
      }
  #endif
  #if defined(WEBP_USE_MIPS_DSP_R2)
      if (VP8GetCPUInfo(kMIPSdspR2)) {
        WebPInitUpsamplersMIPSdspR2();
      }
  #endif
  #if defined(WEBP_USE_MSA)
      if (VP8GetCPUInfo(kMSA)) {
        WebPInitUpsamplersMSA();
      }
  #endif
    }
  
  #if defined(WEBP_USE_NEON)
    if (WEBP_NEON_OMIT_C_CODE ||
        (VP8GetCPUInfo != NULL && VP8GetCPUInfo(kNEON))) {
      WebPInitUpsamplersNEON();
    }
  #endif
  
    assert(WebPUpsamplers[MODE_RGBA] != NULL);
    assert(WebPUpsamplers[MODE_BGRA] != NULL);
    assert(WebPUpsamplers[MODE_rgbA] != NULL);
    assert(WebPUpsamplers[MODE_bgrA] != NULL);
  #if !defined(WEBP_REDUCE_CSP) || !WEBP_NEON_OMIT_C_CODE
    assert(WebPUpsamplers[MODE_RGB] != NULL);
    assert(WebPUpsamplers[MODE_BGR] != NULL);
    assert(WebPUpsamplers[MODE_ARGB] != NULL);
    assert(WebPUpsamplers[MODE_RGBA_4444] != NULL);
    assert(WebPUpsamplers[MODE_RGB_565] != NULL);
    assert(WebPUpsamplers[MODE_Argb] != NULL);
    assert(WebPUpsamplers[MODE_rgbA_4444] != NULL);
  #endif
  
  #endif  // FANCY_UPSAMPLING
  }
  
  //------------------------------------------------------------------------------
  