From e7ff3f9af6bff4b8b1885aa75204b67dbbfe496f Mon Sep 17 00:00:00 2001
From: Pascal Massimino <pascal.massimino@gmail.com>
Date: Thu, 21 Apr 2011 13:32:45 -0700
Subject: [PATCH] merge two ITransforms together when applicable and change the
 TTransform to return the sum directly.

output is bitwise the same, speed up 1-2%. This is preparatory to a
more efficient SSE2 implementation.

Change-Id: I0bcdf05808c93420fbe9dcb75e5e7e55a4ae5b89
---
 src/enc/dsp.c     | 40 ++++++++++++++++++++++++----------------
 src/enc/quant.c   | 14 +++++++-------
 src/enc/vp8enci.h |  5 ++++-
 3 files changed, 35 insertions(+), 24 deletions(-)

diff --git a/src/enc/dsp.c b/src/enc/dsp.c
index 45f977c9..aca199e0 100644
--- a/src/enc/dsp.c
+++ b/src/enc/dsp.c
@@ -49,7 +49,8 @@ static const int kC1 = 20091 + (1 << 16);
 static const int kC2 = 35468;
 #define MUL(a, b) (((a) * (b)) >> 16)
 
-static void ITransform(const uint8_t* ref, const int16_t* in, uint8_t* dst) {
+static inline void ITransformOne(const uint8_t* ref, const int16_t* in,
+                                 uint8_t* dst) {
   int C[4 * 4], *tmp;
   int i;
   tmp = C;
@@ -80,6 +81,13 @@ static void ITransform(const uint8_t* ref, const int16_t* in, uint8_t* dst) {
     tmp++;
   }
 }
+static void ITransform(const uint8_t* ref, const int16_t* in, uint8_t* dst,
+                       int do_two) {
+  ITransformOne(ref, in, dst);
+  if (do_two) {
+    ITransformOne(ref + 4, in + 16, dst + 4);
+  }
+}
 
 static void FTransform(const uint8_t* src, const uint8_t* ref, int16_t* out) {
   int i;
@@ -526,9 +534,12 @@ VP8Metric VP8SSE4x4 = SSE4x4;
 // reconstructed samples.
 
 // Hadamard transform
-static void TTransform(const uint8_t* in, int16_t* out) {
+// Returns the weighted sum of the absolute value of transformed coefficients.
+static int TTransform(const uint8_t* in, const uint16_t* w) {
+  int sum = 0;
   int tmp[16];
   int i;
+  // horizontal pass
   for (i = 0; i < 4; ++i, in += BPS) {
     const int a0 = (in[0] + in[2]) << 2;
     const int a1 = (in[1] + in[3]) << 2;
@@ -539,7 +550,8 @@ static void TTransform(const uint8_t* in, int16_t* out) {
     tmp[2 + i * 4] = a3 - a2;
     tmp[3 + i * 4] = a0 - a1;
   }
-  for (i = 0; i < 4; ++i) {
+  // vertical pass
+  for (i = 0; i < 4; ++i, ++w) {
     const int a0 = (tmp[0 + i] + tmp[8 + i]);
     const int a1 = (tmp[4 + i] + tmp[12+ i]);
     const int a2 = (tmp[4 + i] - tmp[12+ i]);
@@ -548,24 +560,20 @@ static void TTransform(const uint8_t* in, int16_t* out) {
     const int b1 = a3 + a2;
     const int b2 = a3 - a2;
     const int b3 = a0 - a1;
-    out[ 0 + i] = (b0 + (b0 < 0) + 3) >> 3;
-    out[ 4 + i] = (b1 + (b1 < 0) + 3) >> 3;
-    out[ 8 + i] = (b2 + (b2 < 0) + 3) >> 3;
-    out[12 + i] = (b3 + (b3 < 0) + 3) >> 3;
+    // abs((b + (b<0) + 3) >> 3) = (abs(b) + 3) >> 3
+    sum += w[ 0] * ((abs(b0) + 3) >> 3);
+    sum += w[ 4] * ((abs(b1) + 3) >> 3);
+    sum += w[ 8] * ((abs(b2) + 3) >> 3);
+    sum += w[12] * ((abs(b3) + 3) >> 3);
   }
+  return sum;
 }
 
 static int Disto4x4(const uint8_t* const a, const uint8_t* const b,
                     const uint16_t* const w) {
-  int16_t tmp1[16], tmp2[16];
-  int k;
-  int D;
-  TTransform(a, tmp1);
-  TTransform(b, tmp2);
-  D = 0;
-  for (k = 0; k < 16; ++k)
-    D += w[k] * (abs(tmp2[k]) - abs(tmp1[k]));
-  return (abs(D) + 8) >> 4;
+  const int sum1 = TTransform(a, w);
+  const int sum2 = TTransform(b, w);
+  return (abs(sum2 - sum1) + 8) >> 4;
 }
 
 static int Disto16x16(const uint8_t* const a, const uint8_t* const b,
diff --git a/src/enc/quant.c b/src/enc/quant.c
index e4399194..31ec8144 100644
--- a/src/enc/quant.c
+++ b/src/enc/quant.c
@@ -615,8 +615,8 @@ static int ReconstructIntra16(VP8EncIterator* const it,
 
   // Transform back
   VP8ITransformWHT(dc_tmp, tmp[0]);
-  for (n = 0; n < 16; ++n) {
-    VP8ITransform(ref + VP8Scan[n], tmp[n], yuv_out + VP8Scan[n]);
+  for (n = 0; n < 16; n += 2) {
+    VP8ITransform(ref + VP8Scan[n], tmp[n], yuv_out + VP8Scan[n], 1);
   }
 
   return nz;
@@ -642,7 +642,7 @@ static int ReconstructIntra4(VP8EncIterator* const it,
   } else {
     nz = VP8EncQuantizeBlock(tmp, levels, 0, &dqm->y1_);
   }
-  VP8ITransform(ref, tmp, yuv_out);
+  VP8ITransform(ref, tmp, yuv_out, 0);
   return nz;
 }
 
@@ -666,8 +666,8 @@ static int ReconstructUV(VP8EncIterator* const it, VP8ModeScore* const rd,
         for (x = 0; x < 2; ++x, ++n) {
           const int ctx = it->top_nz_[4 + ch + x] + it->left_nz_[4 + ch + y];
           const int non_zero =
-            TrellisQuantizeBlock(it, tmp[n], rd->uv_levels[n], ctx, 2, &dqm->uv_,
-                                 dqm->lambda_trellis_uv_);
+            TrellisQuantizeBlock(it, tmp[n], rd->uv_levels[n], ctx, 2,
+                                 &dqm->uv_, dqm->lambda_trellis_uv_);
           it->top_nz_[4 + ch + x] = it->left_nz_[4 + ch + y] = non_zero;
           nz |= non_zero << n;
         }
@@ -679,8 +679,8 @@ static int ReconstructUV(VP8EncIterator* const it, VP8ModeScore* const rd,
     }
   }
 
-  for (n = 0; n < 8; ++n) {
-    VP8ITransform(ref + VP8Scan[16 + n], tmp[n], yuv_out + VP8Scan[16 + n]);
+  for (n = 0; n < 8; n += 2) {
+    VP8ITransform(ref + VP8Scan[16 + n], tmp[n], yuv_out + VP8Scan[16 + n], 1);
   }
   return (nz << 16);
 }
diff --git a/src/enc/vp8enci.h b/src/enc/vp8enci.h
index b19450d3..9ee6fc4e 100644
--- a/src/enc/vp8enci.h
+++ b/src/enc/vp8enci.h
@@ -416,7 +416,10 @@ int VP8Decimate(VP8EncIterator* const it, VP8ModeScore* const rd, int rd_opt);
 
   // in dsp.c
 // Transforms
-typedef void (*VP8Idct)(const uint8_t* ref, const int16_t* in, uint8_t* dst);
+// VP8Idct: Does one of two inverse transforms. If do_two is set, the transforms
+//          will be done for (ref, in, dst) and (ref + 4, in + 16, dst + 4).
+typedef void (*VP8Idct)(const uint8_t* ref, const int16_t* in, uint8_t* dst,
+                        int do_two);
 typedef void (*VP8Fdct)(const uint8_t* src, const uint8_t* ref, int16_t* out);
 typedef void (*VP8WHT)(const int16_t* in, int16_t* out);
 extern VP8Idct VP8ITransform;