[FFmpeg-devel] [PATCH 2/3] avcodec/wmalosslessdec: optimize sign operation

[zhaoxiu.zeng]

>From b08b4a38c87000fe5549de96f65de6ba77740b30 Mon Sep 17 00:00:00 2001
From: Zeng Zhaoxiu <zhaoxiu.zeng at gmail.com>
Date: Fri, 13 Feb 2015 23:52:29 +0800
Subject: [PATCH 2/3] avcodec/wmalosslessdec: optimize sign operation

Signed-off-by: Zeng Zhaoxiu <zhaoxiu.zeng at gmail.com>
---
 libavcodec/wmalosslessdec.c | 34 ++++++++--------------------------
 1 file changed, 8 insertions(+), 26 deletions(-)

diff --git a/libavcodec/wmalosslessdec.c b/libavcodec/wmalosslessdec.c
index 9bd5e7b..1916594 100644
--- a/libavcodec/wmalosslessdec.c
+++ b/libavcodec/wmalosslessdec.c
@@ -175,6 +175,8 @@ typedef struct WmallDecodeCtx {
     int channel_coeffs[WMALL_MAX_CHANNELS][WMALL_BLOCK_MAX_SIZE];
 } WmallDecodeCtx;
 
+/** Get sign of integer (1 for positive, -1 for negative and 0 for zero) */
+#define WMASIGN(x) ((x > 0) - (x < 0))
 
 static av_cold int decode_init(AVCodecContext *avctx)
 {
@@ -631,22 +633,14 @@ static void mclms_update(WmallDecodeCtx *s, int icoef, int *pred)
             for (i = 0; i < order * num_channels; i++)
                 s->mclms_coeffs[i + ich * order * num_channels] +=
                     s->mclms_updates[s->mclms_recent + i];
-            for (j = 0; j < ich; j++) {
-                if (s->channel_residues[j][icoef] > 0)
-                    s->mclms_coeffs_cur[ich * num_channels + j] += 1;
-                else if (s->channel_residues[j][icoef] < 0)
-                    s->mclms_coeffs_cur[ich * num_channels + j] -= 1;
-            }
+            for (j = 0; j < ich; j++)
+                s->mclms_coeffs_cur[ich * num_channels + j] += WMASIGN(s->channel_residues[j][icoef]);
         } else if (pred_error < 0) {
             for (i = 0; i < order * num_channels; i++)
                 s->mclms_coeffs[i + ich * order * num_channels] -=
                     s->mclms_updates[s->mclms_recent + i];
-            for (j = 0; j < ich; j++) {
-                if (s->channel_residues[j][icoef] > 0)
-                    s->mclms_coeffs_cur[ich * num_channels + j] -= 1;
-                else if (s->channel_residues[j][icoef] < 0)
-                    s->mclms_coeffs_cur[ich * num_channels + j] += 1;
-            }
+            for (j = 0; j < ich; j++)
+                s->mclms_coeffs_cur[ich * num_channels + j] -= WMASIGN(s->channel_residues[j][icoef]);
         }
     }
 
@@ -658,11 +652,7 @@ static void mclms_update(WmallDecodeCtx *s, int icoef, int *pred)
         else if (s->channel_residues[ich][icoef] < -range)
             s->mclms_prevvalues[s->mclms_recent] = -range;
 
-        s->mclms_updates[s->mclms_recent] = 0;
-        if (s->channel_residues[ich][icoef] > 0)
-            s->mclms_updates[s->mclms_recent] = 1;
-        else if (s->channel_residues[ich][icoef] < 0)
-            s->mclms_updates[s->mclms_recent] = -1;
+        s->mclms_updates[s->mclms_recent] = WMASIGN(s->channel_residues[ich][icoef]);
     }
 
     if (s->mclms_recent == 0) {
@@ -724,12 +714,7 @@ static void lms_update(WmallDecodeCtx *s, int ich, int ilms, int input)
     }
 
     s->cdlms[ich][ilms].lms_prevvalues[recent] = av_clip(input, -range, range - 1);
-    if (!input)
-        s->cdlms[ich][ilms].lms_updates[recent] = 0;
-    else if (input < 0)
-        s->cdlms[ich][ilms].lms_updates[recent] = -s->update_speed[ich];
-    else
-        s->cdlms[ich][ilms].lms_updates[recent] = s->update_speed[ich];
+    s->cdlms[ich][ilms].lms_updates[recent] = WMASIGN(input) * s->update_speed[ich];
 
     s->cdlms[ich][ilms].lms_updates[recent + (order >> 4)] >>= 2;
     s->cdlms[ich][ilms].lms_updates[recent + (order >> 3)] >>= 1;
@@ -773,9 +758,6 @@ static void use_normal_update_speed(WmallDecodeCtx *s, int ich)
     s->update_speed[ich] = 8;
 }
 
-/** Get sign of integer (1 for positive, -1 for negative and 0 for zero) */
-#define WMASIGN(x) ((x > 0) - (x < 0))
-
 static void revert_cdlms(WmallDecodeCtx *s, int ch,
                          int coef_begin, int coef_end)
 {
-- 
2.1.0