/src/libwebp/src/dsp/upsampling_sse41.c

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// 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.
// -----------------------------------------------------------------------------
//
// SSE41 version of YUV to RGB upsampling functions.
//
// Author: somnath@google.com (Somnath Banerjee)

#include "src/dsp/dsp.h"

#if defined(WEBP_USE_SSE41)
#include <assert.h>
#include <smmintrin.h>
#include <string.h>

#include "src/dsp/cpu.h"
#include "src/dsp/yuv.h"
#include "src/webp/decode.h"
#include "src/webp/types.h"

#ifdef FANCY_UPSAMPLING

#if !defined(WEBP_REDUCE_CSP)

// We compute (9*a + 3*b + 3*c + d + 8) / 16 as follows
// u = (9*a + 3*b + 3*c + d + 8) / 16
//   = (a + (a + 3*b + 3*c + d) / 8 + 1) / 2
//   = (a + m + 1) / 2
// where m = (a + 3*b + 3*c + d) / 8
//         = ((a + b + c + d) / 2 + b + c) / 4
//
// Let's say  k = (a + b + c + d) / 4.
// We can compute k as
// k = (s + t + 1) / 2 - ((a^d) | (b^c) | (s^t)) & 1
// where s = (a + d + 1) / 2 and t = (b + c + 1) / 2
//
// Then m can be written as
// m = (k + t + 1) / 2 - (((b^c) & (s^t)) | (k^t)) & 1

// Computes out = (k + in + 1) / 2 - ((ij & (s^t)) | (k^in)) & 1
#define GET_M(ij, in, out)                                                     \
  do {                                                                         \
    const __m128i tmp0 = _mm_avg_epu8(k, (in));   /* (k + in + 1) / 2 */       \
    const __m128i tmp1 = _mm_and_si128((ij), st); /* (ij) & (s^t) */           \
    const __m128i tmp2 = _mm_xor_si128(k, (in));  /* (k^in) */                 \
    const __m128i tmp3 =                                                       \
        _mm_or_si128(tmp1, tmp2); /* ((ij) & (s^t)) | (k^in) */                \
    const __m128i tmp4 = _mm_and_si128(tmp3, one); /* & 1 -> lsb_correction */ \
    (out) = _mm_sub_epi8(tmp0, tmp4); /* (k + in + 1) / 2 - lsb_correction */  \
  } while (0)

// pack and store two alternating pixel rows
#define PACK_AND_STORE(a, b, da, db, out)                       \
  do {                                                          \
    const __m128i t_a =                                         \
        _mm_avg_epu8(a, da); /* (9a + 3b + 3c +  d + 8) / 16 */ \
    const __m128i t_b =                                         \
        _mm_avg_epu8(b, db); /* (3a + 9b +  c + 3d + 8) / 16 */ \
    const __m128i t_1 = _mm_unpacklo_epi8(t_a, t_b);            \
    const __m128i t_2 = _mm_unpackhi_epi8(t_a, t_b);            \
    _mm_store_si128(((__m128i*)(out)) + 0, t_1);                \
    _mm_store_si128(((__m128i*)(out)) + 1, t_2);                \
  } while (0)

// Loads 17 pixels each from rows r1 and r2 and generates 32 pixels.
#define UPSAMPLE_32PIXELS(r1, r2, out)                                         \
  do {                                                                         \
    const __m128i one = _mm_set1_epi8(1);                                      \
    const __m128i a = _mm_loadu_si128((const __m128i*)&(r1)[0]);               \
    const __m128i b = _mm_loadu_si128((const __m128i*)&(r1)[1]);               \
    const __m128i c = _mm_loadu_si128((const __m128i*)&(r2)[0]);               \
    const __m128i d = _mm_loadu_si128((const __m128i*)&(r2)[1]);               \
                                                                               \
    const __m128i s = _mm_avg_epu8(a, d);   /* s = (a + d + 1) / 2 */          \
    const __m128i t = _mm_avg_epu8(b, c);   /* t = (b + c + 1) / 2 */          \
    const __m128i st = _mm_xor_si128(s, t); /* st = s^t */                     \
                                                                               \
    const __m128i ad = _mm_xor_si128(a, d); /* ad = a^d */                     \
    const __m128i bc = _mm_xor_si128(b, c); /* bc = b^c */                     \
                                                                               \
    const __m128i t1 = _mm_or_si128(ad, bc);   /* (a^d) | (b^c) */             \
    const __m128i t2 = _mm_or_si128(t1, st);   /* (a^d) | (b^c) | (s^t) */     \
    const __m128i t3 = _mm_and_si128(t2, one); /* (a^d) | (b^c) | (s^t) & 1 */ \
    const __m128i t4 = _mm_avg_epu8(s, t);                                     \
    const __m128i k = _mm_sub_epi8(t4, t3); /* k = (a + b + c + d) / 4 */      \
    __m128i diag1, diag2;                                                      \
                                                                               \
    GET_M(bc, t, diag1); /* diag1 = (a + 3b + 3c + d) / 8 */                   \
    GET_M(ad, s, diag2); /* diag2 = (3a + b + c + 3d) / 8 */                   \
                                                                               \
    /* pack the alternate pixels */                                            \
    PACK_AND_STORE(a, b, diag1, diag2, (out) + 0);      /* store top */        \
    PACK_AND_STORE(c, d, diag2, diag1, (out) + 2 * 32); /* store bottom */     \
  } while (0)

// Turn the macro into a function for reducing code-size when non-critical
static void Upsample32Pixels_SSE41(const uint8_t* WEBP_RESTRICT const r1,
                                   const uint8_t* WEBP_RESTRICT const r2,
                                   uint8_t* WEBP_RESTRICT const out) {
  UPSAMPLE_32PIXELS(r1, r2, out);
}

#define UPSAMPLE_LAST_BLOCK(tb, bb, num_pixels, out)                         \
  {                                                                          \
    uint8_t r1[17], r2[17];                                                  \
    memcpy(r1, (tb), (num_pixels));                                          \
    memcpy(r2, (bb), (num_pixels));                                          \
    /* replicate last byte */                                                \
    memset(r1 + (num_pixels), r1[(num_pixels) - 1], 17 - (num_pixels));      \
    memset(r2 + (num_pixels), r2[(num_pixels) - 1], 17 - (num_pixels));      \
    /* using the shared function instead of the macro saves ~3k code size */ \
    Upsample32Pixels_SSE41(r1, r2, out);                                     \
  }

#define CONVERT2RGB_32(FUNC, XSTEP, top_y, bottom_y, top_dst, bottom_dst, \
                       cur_x)                                             \
  do {                                                                    \
    FUNC##32_SSE41((top_y) + (cur_x), r_u, r_v,                           \
                   (top_dst) + (cur_x) * (XSTEP));                        \
    if ((bottom_y) != NULL) {                                             \
      FUNC##32_SSE41((bottom_y) + (cur_x), r_u + 64, r_v + 64,            \
                     (bottom_dst) + (cur_x) * (XSTEP));                   \
    }                                                                     \
  } while (0)

#define SSE4_UPSAMPLE_FUNC(FUNC_NAME, FUNC, XSTEP)                            \
  static void FUNC_NAME(                                                      \
      const uint8_t* WEBP_RESTRICT top_y,                                     \
      const uint8_t* WEBP_RESTRICT bottom_y,                                  \
      const uint8_t* WEBP_RESTRICT top_u, const uint8_t* WEBP_RESTRICT top_v, \
      const uint8_t* WEBP_RESTRICT cur_u, const uint8_t* WEBP_RESTRICT cur_v, \
      uint8_t* WEBP_RESTRICT top_dst, uint8_t* WEBP_RESTRICT bottom_dst,      \
      int len) {                                                              \
    int uv_pos, pos;                                                          \
    /* 16byte-aligned array to cache reconstructed u and v */                 \
    uint8_t uv_buf[14 * 32 + 15] = {0};                                       \
    uint8_t* const r_u =                                                      \
        (uint8_t*)((uintptr_t)(uv_buf + 15) & ~(uintptr_t)15);                \
    uint8_t* const r_v = r_u + 32;                                            \
                                                                              \
    assert(top_y != NULL);                                                    \
    { /* Treat the first pixel in regular way */                              \
      const int u_diag = ((top_u[0] + cur_u[0]) >> 1) + 1;                    \
      const int v_diag = ((top_v[0] + cur_v[0]) >> 1) + 1;                    \
      const int u0_t = (top_u[0] + u_diag) >> 1;                              \
      const int v0_t = (top_v[0] + v_diag) >> 1;                              \
      FUNC(top_y[0], u0_t, v0_t, top_dst);                                    \
      if (bottom_y != NULL) {                                                 \
        const int u0_b = (cur_u[0] + u_diag) >> 1;                            \
        const int v0_b = (cur_v[0] + v_diag) >> 1;                            \
        FUNC(bottom_y[0], u0_b, v0_b, bottom_dst);                            \
      }                                                                       \
    }                                                                         \
    /* For UPSAMPLE_32PIXELS, 17 u/v values must be read-able for each block  \
     */                                                                       \
    for (pos = 1, uv_pos = 0; pos + 32 + 1 <= len; pos += 32, uv_pos += 16) { \
      UPSAMPLE_32PIXELS(top_u + uv_pos, cur_u + uv_pos, r_u);                 \
      UPSAMPLE_32PIXELS(top_v + uv_pos, cur_v + uv_pos, r_v);                 \
      CONVERT2RGB_32(FUNC, XSTEP, top_y, bottom_y, top_dst, bottom_dst, pos); \
    }                                                                         \
    if (len > 1) {                                                            \
      const int left_over = ((len + 1) >> 1) - (pos >> 1);                    \
      uint8_t* const tmp_top_dst = r_u + 4 * 32;                              \
      uint8_t* const tmp_bottom_dst = tmp_top_dst + 4 * 32;                   \
      uint8_t* const tmp_top = tmp_bottom_dst + 4 * 32;                       \
      uint8_t* const tmp_bottom = (bottom_y == NULL) ? NULL : tmp_top + 32;   \
      assert(left_over > 0);                                                  \
      UPSAMPLE_LAST_BLOCK(top_u + uv_pos, cur_u + uv_pos, left_over, r_u);    \
      UPSAMPLE_LAST_BLOCK(top_v + uv_pos, cur_v + uv_pos, left_over, r_v);    \
      memcpy(tmp_top, top_y + pos, len - pos);                                \
      if (bottom_y != NULL) memcpy(tmp_bottom, bottom_y + pos, len - pos);    \
      CONVERT2RGB_32(FUNC, XSTEP, tmp_top, tmp_bottom, tmp_top_dst,           \
                     tmp_bottom_dst, 0);                                      \
      memcpy(top_dst + pos * (XSTEP), tmp_top_dst, (len - pos) * (XSTEP));    \
      if (bottom_y != NULL) {                                                 \
        memcpy(bottom_dst + pos * (XSTEP), tmp_bottom_dst,                    \
               (len - pos) * (XSTEP));                                        \
      }                                                                       \
    }                                                                         \
  }

// SSE4 variants of the fancy upsampler.
SSE4_UPSAMPLE_FUNC(UpsampleRgbLinePair_SSE41, VP8YuvToRgb, 3)
SSE4_UPSAMPLE_FUNC(UpsampleBgrLinePair_SSE41, VP8YuvToBgr, 3)

#undef GET_M
#undef PACK_AND_STORE
#undef UPSAMPLE_32PIXELS
#undef UPSAMPLE_LAST_BLOCK
#undef CONVERT2RGB
#undef CONVERT2RGB_32
#undef SSE4_UPSAMPLE_FUNC

#endif  // WEBP_REDUCE_CSP

//------------------------------------------------------------------------------
// Entry point

extern WebPUpsampleLinePairFunc WebPUpsamplers[/* MODE_LAST */];

extern void WebPInitUpsamplersSSE41(void);

WEBP_TSAN_IGNORE_FUNCTION void WebPInitUpsamplersSSE41(void) {
#if !defined(WEBP_REDUCE_CSP)
  WebPUpsamplers[MODE_RGB] = UpsampleRgbLinePair_SSE41;
  WebPUpsamplers[MODE_BGR] = UpsampleBgrLinePair_SSE41;
#endif  // WEBP_REDUCE_CSP
}

#endif  // FANCY_UPSAMPLING

//------------------------------------------------------------------------------

extern WebPYUV444Converter WebPYUV444Converters[/* MODE_LAST */];
extern void WebPInitYUV444ConvertersSSE41(void);

#define YUV444_FUNC(FUNC_NAME, CALL, CALL_C, XSTEP)                          \
  extern void CALL_C(                                                        \
      const uint8_t* WEBP_RESTRICT y, const uint8_t* WEBP_RESTRICT u,        \
      const uint8_t* WEBP_RESTRICT v, uint8_t* WEBP_RESTRICT dst, int len);  \
  static void FUNC_NAME(                                                     \
      const uint8_t* WEBP_RESTRICT y, const uint8_t* WEBP_RESTRICT u,        \
      const uint8_t* WEBP_RESTRICT v, uint8_t* WEBP_RESTRICT dst, int len) { \
    int i;                                                                   \
    const int max_len = len & ~31;                                           \
    for (i = 0; i < max_len; i += 32) {                                      \
      CALL(y + i, u + i, v + i, dst + i * (XSTEP));                          \
    }                                                                        \
    if (i < len) { /* C-fallback */                                          \
      CALL_C(y + i, u + i, v + i, dst + i * (XSTEP), len - i);               \
    }                                                                        \
  }

#if !defined(WEBP_REDUCE_CSP)
YUV444_FUNC(Yuv444ToRgb_SSE41, VP8YuvToRgb32_SSE41, WebPYuv444ToRgb_C, 3)
YUV444_FUNC(Yuv444ToBgr_SSE41, VP8YuvToBgr32_SSE41, WebPYuv444ToBgr_C, 3)
#endif  // WEBP_REDUCE_CSP

WEBP_TSAN_IGNORE_FUNCTION void WebPInitYUV444ConvertersSSE41(void) {
#if !defined(WEBP_REDUCE_CSP)
  WebPYUV444Converters[MODE_RGB] = Yuv444ToRgb_SSE41;
  WebPYUV444Converters[MODE_BGR] = Yuv444ToBgr_SSE41;
#endif  // WEBP_REDUCE_CSP
}

#else

WEBP_DSP_INIT_STUB(WebPInitYUV444ConvertersSSE41)

#endif  // WEBP_USE_SSE41

#if !(defined(FANCY_UPSAMPLING) && defined(WEBP_USE_SSE41))
WEBP_DSP_INIT_STUB(WebPInitUpsamplersSSE41)
#endif

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Created: 2025-08-11 08:01