Avoid code duplication between mace3_decode_frame() and mace6_decode_frame()

Originally committed as revision 15568 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mace.c

@@ -241,8 +241,9 @@ static int mace3_decode_frame(AVCodecContext *avctx,
     int16_t *samples = data;
     MACEContext *ctx = avctx->priv_data;
     int i, j, k, l;
+    int is_mace3 = (avctx->codec_id == CODEC_ID_MACE3);
 
-    if (*data_size < 2 * 3 * buf_size) {
+    if (*data_size < (3 * buf_size << (2-is_mace3))) {
         av_log(avctx, AV_LOG_ERROR, "Output buffer too small!\n");
         return -1;
     }
@@ -250,51 +251,28 @@ static int mace3_decode_frame(AVCodecContext *avctx,
     for(i = 0; i < avctx->channels; i++) {
         int16_t *output = samples + i;
 
-        for (j=0; j < buf_size / 2 / avctx->channels; j++)
-            for (k=0; k < 2; k++) {
-                uint8_t pkt = buf[i*2 + j*2*avctx->channels + k];
-                uint8_t val[3] = {pkt & 7, (pkt >> 3) & 3, pkt >> 5};
+        for (j=0; j < buf_size / (avctx->channels << is_mace3); j++)
+            for (k=0; k < (1 << is_mace3); k++) {
+                uint8_t pkt = buf[(i << is_mace3) +
+                                  (j*avctx->channels << is_mace3) + k];
+
+                uint8_t val[2][3] = {{pkt >> 5, (pkt >> 3) & 3, pkt & 7 },
+                                     {pkt & 7 , (pkt >> 3) & 3, pkt >> 5}};
 
                 for (l=0; l < 3; l++) {
-                    chomp3(&ctx->chd[i], output, val[l], l, avctx->channels);
-                    output += avctx->channels;
+                    if (is_mace3)
+                        chomp3(&ctx->chd[i], output, val[1][l], l,
+                               avctx->channels);
+                    else
+                        chomp6(&ctx->chd[i], output, val[0][l], l,
+                               avctx->channels);
+
+                    output += avctx->channels << (1-is_mace3);
                 }
             }
     }
 
-    *data_size = 2 * 3 * buf_size;
-
-    return buf_size;
-}
-
-static int mace6_decode_frame(AVCodecContext *avctx,
-                              void *data, int *data_size,
-                              const uint8_t *buf, int buf_size)
-{
-    int16_t *samples = data;
-    MACEContext *ctx = avctx->priv_data;
-    int i, j, l;
-
-    if (*data_size < 2 * 6 * buf_size) {
-        av_log(avctx, AV_LOG_ERROR, "Output buffer too small!\n");
-        return -1;
-    }
-
-    for(i = 0; i < avctx->channels; i++) {
-        int16_t *output = samples + i;
-
-        for (j = 0; j < buf_size / avctx->channels; j++) {
-            uint8_t pkt = buf[i + j*avctx->channels];
-            uint8_t val[3] = {pkt >> 5, (pkt >> 3) & 3, pkt & 7};
-
-            for (l=0; l < 3; l++) {
-                chomp6(&ctx->chd[i], output, val[l], l, avctx->channels);
-                output += avctx->channels << 1;
-            }
-        }
-    }
-
-    *data_size = 2 * 6 * buf_size;
+    *data_size = 3 * buf_size << (2-is_mace3);
 
     return buf_size;
 }
@@ -319,7 +297,7 @@ AVCodec mace6_decoder = {
     mace_decode_init,
     NULL,
     NULL,
-    mace6_decode_frame,
+    mace3_decode_frame,
     .long_name = NULL_IF_CONFIG_SMALL("MACE (Macintosh Audio Compression/Expansion) 6:1"),
 };