From 1d62acf6af32f965587d3dc598a39d65a50d0c45 Mon Sep 17 00:00:00 2001
From: Djordje Pesut <djordje.pesut@imgtec.com>
Date: Tue, 22 Apr 2014 14:55:14 +0200
Subject: [PATCH] MIPS: MIPS32r1: Added optimization for HuffmanCost functions.

HuffmanCost and HuffmanCostCombined optimized and added
'const' to some variables from ExtraCost functions.

Change-Id: I28b2b357a06766bee78bdab294b5fc8c05ac120d
---
 src/dsp/lossless_mips32.c | 97 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 91 insertions(+), 6 deletions(-)

diff --git a/src/dsp/lossless_mips32.c b/src/dsp/lossless_mips32.c
index dc329118..a8d3ca7f 100644
--- a/src/dsp/lossless_mips32.c
+++ b/src/dsp/lossless_mips32.c
@@ -17,9 +17,10 @@
 
 #if defined(WEBP_USE_MIPS32)
 
+#include <assert.h>
 #include <math.h>
 #include <stdlib.h>
-#include <assert.h>
+#include <string.h>
 
 #define APPROX_LOG_WITH_CORRECTION_MAX  65536
 #define APPROX_LOG_MAX                   4096
@@ -108,8 +109,8 @@ static float FastLog2Slow(int v) {
 //   return (double)cost;
 static double ExtraCost(const int* const population, int length) {
   int i, temp0, temp1;
-  int* pop = (int*)&population[4];
-  const int* LoopEnd = (int*)&population[length];
+  const int* pop = &population[4];
+  const int* const LoopEnd = &population[length];
 
   __asm__ volatile(
     "mult   $zero,    $zero                  \n\t"
@@ -154,9 +155,9 @@ static double ExtraCost(const int* const population, int length) {
 static double ExtraCostCombined(const int* const X, const int* const Y,
                                 int length) {
   int i, temp0, temp1, temp2, temp3;
-  int* pX = (int*)&X[4];
-  int* pY = (int*)&Y[4];
-  const int* LoopEnd = (int*)&X[length];
+  const int* pX = &X[4];
+  const int* pY = &Y[4];
+  const int* const LoopEnd = &X[length];
 
   __asm__ volatile(
     "mult   $zero,    $zero                  \n\t"
@@ -188,6 +189,88 @@ static double ExtraCostCombined(const int* const X, const int* const Y,
   return (double)((int64_t)temp0 << 32 | temp1);
 }
 
+#define HUFFMAN_COST_PASS                                 \
+  __asm__ volatile(                                       \
+    "sll   %[temp1],  %[temp0],    3           \n\t"      \
+    "addiu %[temp3],  %[streak],   -3          \n\t"      \
+    "addu  %[temp2],  %[pstreaks], %[temp1]    \n\t"      \
+    "blez  %[temp3],  1f                       \n\t"      \
+    "srl   %[temp1],  %[temp1],    1           \n\t"      \
+    "addu  %[temp3],  %[pcnts],    %[temp1]    \n\t"      \
+    "lw    %[temp0],  4(%[temp2])              \n\t"      \
+    "lw    %[temp1],  0(%[temp3])              \n\t"      \
+    "addu  %[temp0],  %[temp0],    %[streak]   \n\t"      \
+    "addiu %[temp1],  %[temp1],    1           \n\t"      \
+    "sw    %[temp0],  4(%[temp2])              \n\t"      \
+    "sw    %[temp1],  0(%[temp3])              \n\t"      \
+    "b     2f                                  \n\t"      \
+  "1:                                          \n\t"      \
+    "lw    %[temp0],  0(%[temp2])              \n\t"      \
+    "addu  %[temp0],  %[temp0],    %[streak]   \n\t"      \
+    "sw    %[temp0],  0(%[temp2])              \n\t"      \
+  "2:                                          \n\t"      \
+    : [temp1]"=&r"(temp1), [temp2]"=&r"(temp2),           \
+      [temp3]"=&r"(temp3), [temp0]"+r"(temp0)             \
+    : [pstreaks]"r"(pstreaks), [pcnts]"r"(pcnts),         \
+      [streak]"r"(streak)                                 \
+    : "memory"                                            \
+  );
+
+// Returns the various RLE counts
+static VP8LStreaks HuffmanCostCount(const int* population, int length) {
+  int i;
+  int streak = 0;
+  VP8LStreaks stats;
+  int* const pstreaks = &stats.streaks[0][0];
+  int* const pcnts = &stats.counts[0];
+  int temp0, temp1, temp2, temp3;
+  memset(&stats, 0, sizeof(stats));
+  for (i = 0; i < length - 1; ++i) {
+    ++streak;
+    if (population[i] == population[i + 1]) {
+      continue;
+    }
+    temp0 = population[i] != 0;
+    HUFFMAN_COST_PASS
+    streak = 0;
+  }
+  ++streak;
+  temp0 = population[i] != 0;
+  HUFFMAN_COST_PASS
+
+  return stats;
+}
+
+static VP8LStreaks HuffmanCostCombinedCount(const int* X, const int* Y,
+                                            int length) {
+  int i;
+  int streak = 0;
+  VP8LStreaks stats;
+  int* const pstreaks = &stats.streaks[0][0];
+  int* const pcnts = &stats.counts[0];
+  int temp0, temp1, temp2, temp3;
+  memset(&stats, 0, sizeof(stats));
+  for (i = 0; i < length - 1; ++i) {
+    const int xy = X[i] + Y[i];
+    const int xy_next = X[i + 1] + Y[i + 1];
+    ++streak;
+    if (xy == xy_next) {
+      continue;
+    }
+    temp0 = xy != 0;
+    HUFFMAN_COST_PASS
+    streak = 0;
+  }
+  {
+    const int xy = X[i] + Y[i];
+    ++streak;
+    temp0 = xy != 0;
+    HUFFMAN_COST_PASS
+  }
+
+  return stats;
+}
+
 #endif  // WEBP_USE_MIPS32
 
 //------------------------------------------------------------------------------
@@ -201,5 +284,7 @@ void VP8LDspInitMIPS32(void) {
   VP8LFastLog2Slow = FastLog2Slow;
   VP8LExtraCost = ExtraCost;
   VP8LExtraCostCombined = ExtraCostCombined;
+  VP8LHuffmanCostCount = HuffmanCostCount;
+  VP8LHuffmanCostCombinedCount = HuffmanCostCombinedCount;
 #endif  // WEBP_USE_MIPS32
 }