ALAC: use sign_extend() from mathops.h

Originally committed as revision 17739 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/alac.c

@@ -56,6 +56,7 @@
 #include "bitstream.h"
 #include "bytestream.h"
 #include "unary.h"
+#include "mathops.h"
 
 #define ALAC_EXTRADATA_SIZE 36
 #define MAX_CHANNELS 2
@@ -229,11 +230,6 @@ static void bastardized_rice_decompress(ALACContext *alac,
     }
 }
 
-static inline int32_t extend_sign32(int32_t val, int bits)
-{
-    return (val << (32 - bits)) >> (32 - bits);
-}
-
 static inline int sign_only(int v)
 {
     return v ? FFSIGN(v) : 0;
@@ -273,7 +269,7 @@ static void predictor_decompress_fir_adapt(int32_t *error_buffer,
             prev_value = buffer_out[i];
             error_value = error_buffer[i+1];
             buffer_out[i+1] =
-                extend_sign32((prev_value + error_value), readsamplesize);
+                sign_extend((prev_value + error_value), readsamplesize);
         }
         return;
     }
@@ -284,7 +280,7 @@ static void predictor_decompress_fir_adapt(int32_t *error_buffer,
             int32_t val;
 
             val = buffer_out[i] + error_buffer[i+1];
-            val = extend_sign32(val, readsamplesize);
+            val = sign_extend(val, readsamplesize);
             buffer_out[i+1] = val;
         }
 
@@ -319,7 +315,7 @@ static void predictor_decompress_fir_adapt(int32_t *error_buffer,
             outval = (1 << (predictor_quantitization-1)) + sum;
             outval = outval >> predictor_quantitization;
             outval = outval + buffer_out[0] + error_val;
-            outval = extend_sign32(outval, readsamplesize);
+            outval = sign_extend(outval, readsamplesize);
 
             buffer_out[predictor_coef_num+1] = outval;
 
@@ -545,7 +541,7 @@ static int alac_decode_frame(AVCodecContext *avctx,
                 int32_t audiobits;
 
                 audiobits = get_bits_long(&alac->gb, alac->setinfo_sample_size);
-                audiobits = extend_sign32(audiobits, alac->setinfo_sample_size);
+                audiobits = sign_extend(audiobits, alac->setinfo_sample_size);
 
                 alac->outputsamples_buffer[chan][i] = audiobits;
             }