special version of sample formatting for common cases

diff --git a/src/flac/decode.c b/src/flac/decode.c
index 5ac21aa..d0f4585 100644 (file)
--- a/src/flac/decode.c
+++ b/src/flac/decode.c
@@ -904,29 +904,58 @@ FLAC__StreamDecoderWriteStatus write_callback(const FLAC__StreamDecoder *decoder
                                        &decoder_session->replaygain.dither_context
                                );
                        }
-                       else if(bps+shift == 8) {
-                               if(is_unsigned_samples) {
-                                       for(sample = wide_sample = 0; wide_sample < wide_samples; wide_sample++)
-                                               for(channel = 0; channel < channels; channel++, sample++)
-                                                       u8buffer[sample] = (FLAC__uint8)(buffer[channel][wide_sample] + 0x80);
-                               }
-                               else {
-                                       for(sample = wide_sample = 0; wide_sample < wide_samples; wide_sample++)
-                                               for(channel = 0; channel < channels; channel++, sample++)
-                                                       s8buffer[sample] = (FLAC__int8)(buffer[channel][wide_sample]);
-                               }
-                               bytes_to_write = sample;
+                       /* first some special code for common cases */
+                       else if(is_big_endian == is_big_endian_host_ && !is_unsigned_samples && channels == 2 && bps+shift == 16) {
+                               FLAC__int16 *buf1_ = s16buffer + 1;
+                               if(is_big_endian)
+                                       memcpy(s16buffer, ((FLAC__byte*)(buffer[0]))+2, sizeof(FLAC__int32) * wide_samples - 2);
+                               else
+                                       memcpy(s16buffer, buffer[0], sizeof(FLAC__int32) * wide_samples);
+                               for(sample = 0; sample < wide_samples; sample++, buf1_+=2)
+                                       *buf1_ = (FLAC__int16)buffer[1][sample];
+                               bytes_to_write = 4 * sample;
                        }
+                       else if(is_big_endian == is_big_endian_host_ && !is_unsigned_samples && channels == 1 && bps+shift == 16) {
+                               FLAC__int16 *buf1_ = s16buffer;
+                               for(sample = 0; sample < wide_samples; sample++)
+                                       *buf1_++ = (FLAC__int16)buffer[0][sample];
+                               bytes_to_write = 2 * sample;
+                       }
+                       /* generic code for the rest */
                        else if(bps+shift == 16) {
                                if(is_unsigned_samples) {
-                                       for(sample = wide_sample = 0; wide_sample < wide_samples; wide_sample++)
-                                               for(channel = 0; channel < channels; channel++, sample++)
-                                                       u16buffer[sample] = (FLAC__uint16)(buffer[channel][wide_sample] + 0x8000);
+                                       if(channels == 2) {
+                                               for(sample = wide_sample = 0; wide_sample < wide_samples; wide_sample++) {
+                                                       u16buffer[sample++] = (FLAC__uint16)(buffer[0][wide_sample] + 0x8000);
+                                                       u16buffer[sample++] = (FLAC__uint16)(buffer[1][wide_sample] + 0x8000);
+                                               }
+                                       }
+                                       else if(channels == 1) {
+                                               for(sample = wide_sample = 0; wide_sample < wide_samples; wide_sample++)
+                                                       u16buffer[sample++] = (FLAC__uint16)(buffer[0][wide_sample] + 0x8000);
+                                       }
+                                       else { /* works for any 'channels' but above flavors are faster for 1 and 2 */
+                                               for(sample = wide_sample = 0; wide_sample < wide_samples; wide_sample++)
+                                                       for(channel = 0; channel < channels; channel++, sample++)
+                                                               u16buffer[sample] = (FLAC__uint16)(buffer[channel][wide_sample] + 0x8000);
+                                       }
                                }
                                else {
-                                       for(sample = wide_sample = 0; wide_sample < wide_samples; wide_sample++)
-                                               for(channel = 0; channel < channels; channel++, sample++)
-                                                       s16buffer[sample] = (FLAC__int16)(buffer[channel][wide_sample]);
+                                       if(channels == 2) {
+                                               for(sample = wide_sample = 0; wide_sample < wide_samples; wide_sample++) {
+                                                       s16buffer[sample++] = (FLAC__int16)(buffer[0][wide_sample]);
+                                                       s16buffer[sample++] = (FLAC__int16)(buffer[1][wide_sample]);
+                                               }
+                                       }
+                                       else if(channels == 1) {
+                                               for(sample = wide_sample = 0; wide_sample < wide_samples; wide_sample++)
+                                                       s16buffer[sample++] = (FLAC__int16)(buffer[0][wide_sample]);
+                                       }
+                                       else { /* works for any 'channels' but above flavors are faster for 1 and 2 */
+                                               for(sample = wide_sample = 0; wide_sample < wide_samples; wide_sample++)
+                                                       for(channel = 0; channel < channels; channel++, sample++)
+                                                               s16buffer[sample] = (FLAC__int16)(buffer[channel][wide_sample]);
+                                       }
                                }
                                if(is_big_endian != is_big_endian_host_) {
                                        unsigned char tmp;
@@ -984,6 +1013,19 @@ FLAC__StreamDecoderWriteStatus write_callback(const FLAC__StreamDecoder *decoder
                                }
                                bytes_to_write = 3 * sample;
                        }
+                       else if(bps+shift == 8) {
+                               if(is_unsigned_samples) {
+                                       for(sample = wide_sample = 0; wide_sample < wide_samples; wide_sample++)
+                                               for(channel = 0; channel < channels; channel++, sample++)
+                                                       u8buffer[sample] = (FLAC__uint8)(buffer[channel][wide_sample] + 0x80);
+                               }
+                               else {
+                                       for(sample = wide_sample = 0; wide_sample < wide_samples; wide_sample++)
+                                               for(channel = 0; channel < channels; channel++, sample++)
+                                                       s8buffer[sample] = (FLAC__int8)(buffer[channel][wide_sample]);
+                               }
+                               bytes_to_write = sample;
+                       }
                        else {
                                FLAC__ASSERT(0);
                                /* double protection */