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.h"
20 #include "../enc/vp8enci.h"
21 #include "../utils/utils.h"
22
23 //------------------------------------------------------------------------------
24
SetResidualCoeffsSSE2(const int16_t * const coeffs,VP8Residual * const res)25 static 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
GetResidualCostSSE2(int ctx0,const VP8Residual * const res)45 static 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
108 extern void VP8EncDspCostInitSSE2(void);
109
VP8EncDspCostInitSSE2(void)110 WEBP_TSAN_IGNORE_FUNCTION void VP8EncDspCostInitSSE2(void) {
111 VP8SetResidualCoeffs = SetResidualCoeffsSSE2;
112 VP8GetResidualCost = GetResidualCostSSE2;
113 }
114
115 #else // !WEBP_USE_SSE2
116
117 WEBP_DSP_INIT_STUB(VP8EncDspCostInitSSE2)
118
119 #endif // WEBP_USE_SSE2
120