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pcm_dither: pass an "end" pointer instead of a sample count

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This is easier and more efficient to loop on, because only two
variables get modified (src and dest).
This commit is contained in:
Max Kellermann 2011-10-09 12:37:32 +02:00
parent a47e9d1a4b
commit 20c6159c04
4 changed files with 16 additions and 21 deletions
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10
src/pcm_dither.c
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@ -72,10 +72,9 @@ pcm_dither_sample_24_to_16(int32_t sample, struct pcm_dither *dither)
void
pcm_dither_24_to_16(struct pcm_dither *dither,
int16_t *dest, const int32_t *src,
unsigned num_samples)
int16_t *dest, const int32_t *src, const int32_t *src_end)
{
while (num_samples-- > 0)
while (src < src_end)
*dest++ = pcm_dither_sample_24_to_16(*src++, dither);
}
@ -87,9 +86,8 @@ pcm_dither_sample_32_to_16(int32_t sample, struct pcm_dither *dither)
void
pcm_dither_32_to_16(struct pcm_dither *dither,
int16_t *dest, const int32_t *src,
unsigned num_samples)
int16_t *dest, const int32_t *src, const int32_t *src_end)
{
while (num_samples-- > 0)
while (src < src_end)
*dest++ = pcm_dither_sample_32_to_16(*src++, dither);
}

6
src/pcm_dither.h
View File

@ -36,12 +36,10 @@ pcm_dither_24_init(struct pcm_dither *dither)
void
pcm_dither_24_to_16(struct pcm_dither *dither,
int16_t *dest, const int32_t *src,
unsigned num_samples);
int16_t *dest, const int32_t *src, const int32_t *src_end);
void
pcm_dither_32_to_16(struct pcm_dither *dither,
int16_t *dest, const int32_t *src,
unsigned num_samples);
int16_t *dest, const int32_t *src, const int32_t *src_end);
#endif

17
src/pcm_format.c
View File

@ -35,18 +35,16 @@ pcm_convert_8_to_16(int16_t *out, const int8_t *in,
static void
pcm_convert_24_to_16(struct pcm_dither *dither,
int16_t *out, const int32_t *in,
unsigned num_samples)
int16_t *out, const int32_t *in, const int32_t *in_end)
{
pcm_dither_24_to_16(dither, out, in, num_samples);
pcm_dither_24_to_16(dither, out, in, in_end);
}
static void
pcm_convert_32_to_16(struct pcm_dither *dither,
int16_t *out, const int32_t *in,
unsigned num_samples)
int16_t *out, const int32_t *in, const int32_t *in_end)
{
pcm_dither_32_to_16(dither, out, in, num_samples);
pcm_dither_32_to_16(dither, out, in, in_end);
}
static int32_t *
@ -63,6 +61,7 @@ pcm_convert_to_16(struct pcm_buffer *buffer, struct pcm_dither *dither,
enum sample_format src_format, const void *src,
size_t src_size, size_t *dest_size_r)
{
const void *src_end = (const char *)src + src_size;
unsigned num_samples;
int16_t *dest;
int32_t *dest32;
@ -95,7 +94,7 @@ pcm_convert_to_16(struct pcm_buffer *buffer, struct pcm_dither *dither,
/* convert to 16 bit in-place */
*dest_size_r = num_samples * sizeof(*dest);
pcm_convert_24_to_16(dither, dest, dest32,
num_samples);
dest32 + num_samples);
return dest;
case SAMPLE_FORMAT_S24_P32:
@ -105,7 +104,7 @@ pcm_convert_to_16(struct pcm_buffer *buffer, struct pcm_dither *dither,
pcm_convert_24_to_16(dither, dest,
(const int32_t *)src,
num_samples);
(const int32_t *)src_end);
return dest;
case SAMPLE_FORMAT_S32:
@ -115,7 +114,7 @@ pcm_convert_to_16(struct pcm_buffer *buffer, struct pcm_dither *dither,
pcm_convert_32_to_16(dither, dest,
(const int32_t *)src,
num_samples);
(const int32_t *)src_end);
return dest;
}

4
test/test_pcm_dither.c
View File

@ -48,7 +48,7 @@ test_pcm_dither_24(void)
int16_t dest[N];
pcm_dither_24_to_16(&dither, dest, src, N);
pcm_dither_24_to_16(&dither, dest, src, src + N);
for (unsigned i = 0; i < N; ++i) {
g_assert_cmpint(dest[i], >=, (src[i] >> 8) - 8);
@ -70,7 +70,7 @@ test_pcm_dither_32(void)
int16_t dest[N];
pcm_dither_32_to_16(&dither, dest, src, N);
pcm_dither_32_to_16(&dither, dest, src, src + N);
for (unsigned i = 0; i < N; ++i) {
g_assert_cmpint(dest[i], >=, (src[i] >> 16) - 8);