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authorJeffrey Goode <jeffg7@gmail.com>2009-11-15 04:57:40 +0000
committerJeffrey Goode <jeffg7@gmail.com>2009-11-15 04:57:40 +0000
commit873c5b6d18dd691e5c096d3a52f8b4de7c2aabdf (patch)
tree5dc3c1bf897cb11de3839313f45ebe244766cf13 /apps/pcmbuf.c
parenta19000b594b5d8b51453f0393b21244e47212161 (diff)
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pcmbuf: consolidate some similar code
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@23628 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'apps/pcmbuf.c')
-rw-r--r--apps/pcmbuf.c103
1 files changed, 49 insertions, 54 deletions
diff --git a/apps/pcmbuf.c b/apps/pcmbuf.c
index 20eafb5865..f573a29e7c 100644
--- a/apps/pcmbuf.c
+++ b/apps/pcmbuf.c
@@ -705,25 +705,51 @@ static size_t find_chunk(size_t length, struct chunkdesc **chunk)
return length / 2;
}
-/* Fade samples in the PCM buffer */
-static void fade_block(int factor, size_t length, size_t *fade_sample,
- struct chunkdesc **fade_chunk)
+/* Returns the number of bytes _NOT_ mixed/faded */
+static size_t crossfade_mix_fade(int factor, size_t length, const char *buf,
+ size_t *out_sample, struct chunkdesc **out_chunk)
{
- while (length > 0 && *fade_chunk != NULL)
+ const int16_t *input_buf = (const int16_t *)buf;
+ int16_t *output_buf = (int16_t *)((*out_chunk)->addr);
+ int16_t *chunk_end = SKIPBYTES(output_buf, (*out_chunk)->size);
+ output_buf = &output_buf[*out_sample];
+ int32_t sample;
+
+ while (length)
{
- /* Fade one sample */
- int16_t *buf = (int16_t *)((*fade_chunk)->addr);
- int32_t sample = buf[*fade_sample];
- buf[(*fade_sample)++] = (sample * factor) >> 8;
- length -= 2;
-
- /* Move to the next chunk as needed */
- if (*fade_sample * 2 >= (*fade_chunk)->size)
+ /* fade left and right channel at once to keep buffer alignment */
+ int i;
+ for (i = 0; i < 2; i++)
+ {
+ if (input_buf)
+ /* fade the input buffer and mix into the chunk */
+ {
+ sample = *input_buf++;
+ sample = ((sample * factor) >> 8) + *output_buf;
+ *output_buf++ = clip_sample_16(sample);
+ }
+ else
+ /* fade the chunk only */
+ {
+ sample = *output_buf;
+ *output_buf++ = (sample * factor) >> 8;
+ }
+ }
+
+ length -= 4; /* 2 samples, each 16 bit -> 4 bytes */
+
+ /* move to next chunk as needed */
+ if (output_buf >= chunk_end)
{
- *fade_chunk = (*fade_chunk)->link;
- *fade_sample = 0;
+ *out_chunk = (*out_chunk)->link;
+ if (!(*out_chunk))
+ return length;
+ output_buf = (int16_t *)((*out_chunk)->addr);
+ chunk_end = SKIPBYTES(output_buf, (*out_chunk)->size);
}
}
+ *out_sample = output_buf - (int16_t *)((*out_chunk)->addr);
+ return 0;
}
/* Initializes crossfader, calculates all necessary parameters and performs
@@ -812,11 +838,13 @@ static void crossfade_start(void)
fade_out_rem -= block_rem;
- fade_block(factor, block_rem, &fade_out_sample, &fade_out_chunk);
+ crossfade_mix_fade(factor, block_rem, NULL,
+ &fade_out_sample, &fade_out_chunk);
}
/* zero out the rest of the buffer */
- fade_block(0, crossfade_rem, &fade_out_sample, &fade_out_chunk);
+ crossfade_mix_fade(0, crossfade_rem, NULL,
+ &fade_out_sample, &fade_out_chunk);
}
/* Initialize fade-in counters */
@@ -833,41 +861,6 @@ static void crossfade_start(void)
logf("crossfade_start done!");
}
-/* Returns the number of bytes _NOT_ mixed */
-static size_t crossfade_mix(int factor, const char *buf, size_t length)
-{
- const int16_t *input_buf = (const int16_t *)buf;
- int16_t *output_buf = (int16_t *)(crossfade_chunk->addr);
- int16_t *chunk_end = SKIPBYTES(output_buf, crossfade_chunk->size);
- output_buf = &output_buf[crossfade_sample];
- int32_t sample;
-
- while (length)
- {
- /* fade left and right channel at once to keep buffer alignment */
- int i;
- for (i = 0; i < 2; i++)
- {
- sample = *input_buf++;
- sample = ((sample * factor) >> 8) + *output_buf;
- *output_buf++ = clip_sample_16(sample);
- }
-
- length -= 4; /* 2 samples, each 16 bit -> 4 bytes */
-
- if (output_buf >= chunk_end)
- {
- crossfade_chunk = crossfade_chunk->link;
- if (!crossfade_chunk)
- return length;
- output_buf = (int16_t *)crossfade_chunk->addr;
- chunk_end = SKIPBYTES(output_buf, crossfade_chunk->size);
- }
- }
- crossfade_sample = output_buf - (int16_t *)crossfade_chunk->addr;
- return 0;
-}
-
/* Perform fade-in of new track */
static void write_to_crossfade(char *buf, size_t length)
{
@@ -892,7 +885,8 @@ static void write_to_crossfade(char *buf, size_t length)
{
/* Mix the data */
size_t fade_total = fade_rem;
- fade_rem = crossfade_mix(factor, buf, fade_rem);
+ fade_rem = crossfade_mix_fade(factor, fade_rem, buf,
+ &crossfade_sample, &crossfade_chunk);
length -= fade_total - fade_rem;
buf += fade_total - fade_rem;
if (!length)
@@ -913,8 +907,9 @@ static void write_to_crossfade(char *buf, size_t length)
{
/* Mix the data */
size_t mix_total = length;
- /* A factor of 256 means no fading */
- length = crossfade_mix(256, buf, length);
+ /* A factor of 256 means mix only, no fading */
+ length = crossfade_mix_fade(256, length, buf,
+ &crossfade_sample, &crossfade_chunk);
buf += mix_total - length;
if (!length)
return;