MIPS: dspr2: added optimization for function GetResidualCost

set/get residual C functions moved to new file in src/dsp
mips32 version of GetResidualCost moved to new file

Change-Id: I7cebb7933a89820ff28c187249a9181f281081d2

src/dsp/cost.c

@@ -0,0 +1,105 @@
+// Copyright 2014 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.
+// -----------------------------------------------------------------------------
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include "./dsp.h"
+#include "../enc/cost.h"
+
+//------------------------------------------------------------------------------
+// Mode costs
+
+static int GetResidualCost(int ctx0, const VP8Residual* const res) {
+  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];
+  const uint16_t* t = res->cost[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);
+  }
+  for (; n < res->last; ++n) {
+    const int v = abs(res->coeffs[n]);
+    const int b = VP8EncBands[n + 1];
+    const int ctx = (v >= 2) ? 2 : v;
+    cost += VP8LevelCost(t, v);
+    t = res->cost[b][ctx];
+  }
+  // Last coefficient is always non-zero
+  {
+    const int v = abs(res->coeffs[n]);
+    assert(v != 0);
+    cost += VP8LevelCost(t, v);
+    if (n < 15) {
+      const int b = VP8EncBands[n + 1];
+      const int ctx = (v == 1) ? 1 : 2;
+      const int last_p0 = res->prob[b][ctx][0];
+      cost += VP8BitCost(0, last_p0);
+    }
+  }
+  return cost;
+}
+
+static void SetResidualCoeffs(const int16_t* const coeffs,
+                              VP8Residual* const res) {
+  int n;
+  res->last = -1;
+  assert(res->first == 0 || coeffs[0] == 0);
+  for (n = 15; n >= 0; --n) {
+    if (coeffs[n]) {
+      res->last = n;
+      break;
+    }
+  }
+  res->coeffs = coeffs;
+}
+
+//------------------------------------------------------------------------------
+// init function
+
+VP8GetResidualCostFunc VP8GetResidualCost;
+VP8SetResidualCoeffsFunc VP8SetResidualCoeffs;
+
+extern void VP8EncDspCostInitMIPS32(void);
+extern void VP8EncDspCostInitMIPSdspR2(void);
+
+#if defined(WEBP_USE_SSE2)
+extern void VP8SetResidualCoeffsSSE2(const int16_t* const coeffs,
+                                     VP8Residual* const res);
+#endif  // WEBP_USE_SSE2
+
+void VP8EncDspCostInit(void) {
+  VP8GetResidualCost = GetResidualCost;
+  VP8SetResidualCoeffs = SetResidualCoeffs;
+
+  // If defined, use CPUInfo() to overwrite some pointers with faster versions.
+  if (VP8GetCPUInfo != NULL) {
+#if defined(WEBP_USE_MIPS32)
+    if (VP8GetCPUInfo(kMIPS32)) {
+      VP8EncDspCostInitMIPS32();
+    }
+#endif
+#if defined(WEBP_USE_MIPS_DSP_R2)
+    if (VP8GetCPUInfo(kMIPSdspR2)) {
+      VP8EncDspCostInitMIPSdspR2();
+    }
+#endif
+#if defined(WEBP_USE_SSE2)
+    if (VP8GetCPUInfo(kSSE2)) {
+      VP8SetResidualCoeffs = VP8SetResidualCoeffsSSE2;
+    }
+#endif
+  }
+}
+
+//------------------------------------------------------------------------------