1// Copyright 2015 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 cost functions
11//
12// Author: Skal (pascal.massimino@gmail.com)
13
14#include "./dsp.h"
15
16#if defined(WEBP_USE_SSE2)
17#include <emmintrin.h>
18
19#include "../enc/cost_enc.h"
20#include "../enc/vp8i_enc.h"
21#include "../utils/utils.h"
22
23//------------------------------------------------------------------------------
24
25static void SetResidualCoeffsSSE2(const int16_t* const coeffs,
26                                  VP8Residual* const res) {
27  const __m128i c0 = _mm_loadu_si128((const __m128i*)(coeffs + 0));
28  const __m128i c1 = _mm_loadu_si128((const __m128i*)(coeffs + 8));
29  // Use SSE2 to compare 16 values with a single instruction.
30  const __m128i zero = _mm_setzero_si128();
31  const __m128i m0 = _mm_packs_epi16(c0, c1);
32  const __m128i m1 = _mm_cmpeq_epi8(m0, zero);
33  // Get the comparison results as a bitmask into 16bits. Negate the mask to get
34  // the position of entries that are not equal to zero. We don't need to mask
35  // out least significant bits according to res->first, since coeffs[0] is 0
36  // if res->first > 0.
37  const uint32_t mask = 0x0000ffffu ^ (uint32_t)_mm_movemask_epi8(m1);
38  // The position of the most significant non-zero bit indicates the position of
39  // the last non-zero value.
40  assert(res->first == 0 || coeffs[0] == 0);
41  res->last = mask ? BitsLog2Floor(mask) : -1;
42  res->coeffs = coeffs;
43}
44
45static int GetResidualCostSSE2(int ctx0, const VP8Residual* const res) {
46  uint8_t levels[16], ctxs[16];
47  uint16_t abs_levels[16];
48  int n = res->first;
49  // should be prob[VP8EncBands[n]], but it's equivalent for n=0 or 1
50  const int p0 = res->prob[n][ctx0][0];
51  CostArrayPtr const costs = res->costs;
52  const uint16_t* t = costs[n][ctx0];
53  // bit_cost(1, p0) is already incorporated in t[] tables, but only if ctx != 0
54  // (as required by the syntax). For ctx0 == 0, we need to add it here or it'll
55  // be missing during the loop.
56  int cost = (ctx0 == 0) ? VP8BitCost(1, p0) : 0;
57
58  if (res->last < 0) {
59    return VP8BitCost(0, p0);
60  }
61
62  {   // precompute clamped levels and contexts, packed to 8b.
63    const __m128i zero = _mm_setzero_si128();
64    const __m128i kCst2 = _mm_set1_epi8(2);
65    const __m128i kCst67 = _mm_set1_epi8(MAX_VARIABLE_LEVEL);
66    const __m128i c0 = _mm_loadu_si128((const __m128i*)&res->coeffs[0]);
67    const __m128i c1 = _mm_loadu_si128((const __m128i*)&res->coeffs[8]);
68    const __m128i D0 = _mm_sub_epi16(zero, c0);
69    const __m128i D1 = _mm_sub_epi16(zero, c1);
70    const __m128i E0 = _mm_max_epi16(c0, D0);   // abs(v), 16b
71    const __m128i E1 = _mm_max_epi16(c1, D1);
72    const __m128i F = _mm_packs_epi16(E0, E1);
73    const __m128i G = _mm_min_epu8(F, kCst2);    // context = 0,1,2
74    const __m128i H = _mm_min_epu8(F, kCst67);   // clamp_level in [0..67]
75
76    _mm_storeu_si128((__m128i*)&ctxs[0], G);
77    _mm_storeu_si128((__m128i*)&levels[0], H);
78
79    _mm_storeu_si128((__m128i*)&abs_levels[0], E0);
80    _mm_storeu_si128((__m128i*)&abs_levels[8], E1);
81  }
82  for (; n < res->last; ++n) {
83    const int ctx = ctxs[n];
84    const int level = levels[n];
85    const int flevel = abs_levels[n];   // full level
86    cost += VP8LevelFixedCosts[flevel] + t[level];  // simplified VP8LevelCost()
87    t = costs[n + 1][ctx];
88  }
89  // Last coefficient is always non-zero
90  {
91    const int level = levels[n];
92    const int flevel = abs_levels[n];
93    assert(flevel != 0);
94    cost += VP8LevelFixedCosts[flevel] + t[level];
95    if (n < 15) {
96      const int b = VP8EncBands[n + 1];
97      const int ctx = ctxs[n];
98      const int last_p0 = res->prob[b][ctx][0];
99      cost += VP8BitCost(0, last_p0);
100    }
101  }
102  return cost;
103}
104
105//------------------------------------------------------------------------------
106// Entry point
107
108extern void VP8EncDspCostInitSSE2(void);
109
110WEBP_TSAN_IGNORE_FUNCTION void VP8EncDspCostInitSSE2(void) {
111  VP8SetResidualCoeffs = SetResidualCoeffsSSE2;
112  VP8GetResidualCost = GetResidualCostSSE2;
113}
114
115#else  // !WEBP_USE_SSE2
116
117WEBP_DSP_INIT_STUB(VP8EncDspCostInitSSE2)
118
119#endif  // WEBP_USE_SSE2
120