libwebp: update to 0.5.0

third_party/libwebp/dsp/cost_sse2.c

+// Copyright 2015 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.
+// -----------------------------------------------------------------------------
+//
+// SSE2 version of cost functions
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include "./dsp.h"
+
+#if defined(WEBP_USE_SSE2)
+#include <emmintrin.h>
+
+#include "../enc/cost.h"
+#include "../enc/vp8enci.h"
+#include "../utils/utils.h"
+
+//------------------------------------------------------------------------------
+
+static void SetResidualCoeffsSSE2(const int16_t* const coeffs,
+                                  VP8Residual* const res) {
+  const __m128i c0 = _mm_loadu_si128((const __m128i*)(coeffs + 0));
+  const __m128i c1 = _mm_loadu_si128((const __m128i*)(coeffs + 8));
+  // Use SSE2 to compare 16 values with a single instruction.
+  const __m128i zero = _mm_setzero_si128();
+  const __m128i m0 = _mm_packs_epi16(c0, c1);
+  const __m128i m1 = _mm_cmpeq_epi8(m0, zero);
+  // Get the comparison results as a bitmask into 16bits. Negate the mask to get
+  // the position of entries that are not equal to zero. We don't need to mask
+  // out least significant bits according to res->first, since coeffs[0] is 0
+  // if res->first > 0.
+  const uint32_t mask = 0x0000ffffu ^ (uint32_t)_mm_movemask_epi8(m1);
+  // The position of the most significant non-zero bit indicates the position of
+  // the last non-zero value.
+  assert(res->first == 0 || coeffs[0] == 0);
+  res->last = mask ? BitsLog2Floor(mask) : -1;
+  res->coeffs = coeffs;
+}
+
+static int GetResidualCostSSE2(int ctx0, const VP8Residual* const res) {
+  uint8_t levels[16], ctxs[16];
+  uint16_t abs_levels[16];
+  int n = res->first;
+  // should be prob[VP8EncBands[n]], but it's equivalent for n=0 or 1
+  const int p0 = res->prob[n][ctx0][0];
+  CostArrayPtr const costs = res->costs;
+  const uint16_t* t = costs[n][ctx0];
+  // bit_cost(1, p0) is already incorporated in t[] tables, but only if ctx != 0
+  // (as required by the syntax). For ctx0 == 0, we need to add it here or it'll
+  // be missing during the loop.
+  int cost = (ctx0 == 0) ? VP8BitCost(1, p0) : 0;
+
+  if (res->last < 0) {
+    return VP8BitCost(0, p0);
+  }
+
+  {   // precompute clamped levels and contexts, packed to 8b.
+    const __m128i zero = _mm_setzero_si128();
+    const __m128i kCst2 = _mm_set1_epi8(2);
+    const __m128i kCst67 = _mm_set1_epi8(MAX_VARIABLE_LEVEL);
+    const __m128i c0 = _mm_loadu_si128((const __m128i*)&res->coeffs[0]);
+    const __m128i c1 = _mm_loadu_si128((const __m128i*)&res->coeffs[8]);
+    const __m128i D0 = _mm_sub_epi16(zero, c0);
+    const __m128i D1 = _mm_sub_epi16(zero, c1);
+    const __m128i E0 = _mm_max_epi16(c0, D0);   // abs(v), 16b
+    const __m128i E1 = _mm_max_epi16(c1, D1);
+    const __m128i F = _mm_packs_epi16(E0, E1);
+    const __m128i G = _mm_min_epu8(F, kCst2);    // context = 0,1,2
+    const __m128i H = _mm_min_epu8(F, kCst67);   // clamp_level in [0..67]
+
+    _mm_storeu_si128((__m128i*)&ctxs[0], G);
+    _mm_storeu_si128((__m128i*)&levels[0], H);
+
+    _mm_storeu_si128((__m128i*)&abs_levels[0], E0);
+    _mm_storeu_si128((__m128i*)&abs_levels[8], E1);
+  }
+  for (; n < res->last; ++n) {
+    const int ctx = ctxs[n];
+    const int level = levels[n];
+    const int flevel = abs_levels[n];   // full level
+    cost += VP8LevelFixedCosts[flevel] + t[level];  // simplified VP8LevelCost()
+    t = costs[n + 1][ctx];
+  }
+  // Last coefficient is always non-zero
+  {
+    const int level = levels[n];
+    const int flevel = abs_levels[n];
+    assert(flevel != 0);
+    cost += VP8LevelFixedCosts[flevel] + t[level];
+    if (n < 15) {
+      const int b = VP8EncBands[n + 1];
+      const int ctx = ctxs[n];
+      const int last_p0 = res->prob[b][ctx][0];
+      cost += VP8BitCost(0, last_p0);
+    }
+  }
+  return cost;
+}
+
+//------------------------------------------------------------------------------
+// Entry point
+
+extern void VP8EncDspCostInitSSE2(void);
+
+WEBP_TSAN_IGNORE_FUNCTION void VP8EncDspCostInitSSE2(void) {
+  VP8SetResidualCoeffs = SetResidualCoeffsSSE2;
+  VP8GetResidualCost = GetResidualCostSSE2;
+}
+
+#else  // !WEBP_USE_SSE2
+
+WEBP_DSP_INIT_STUB(VP8EncDspCostInitSSE2)
+
+#endif  // WEBP_USE_SSE2