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pcm_utils: added pcm_range() 

Make the code more readable by moving the range checks to pcm_range().
gcc does quite a good job at optimizing it: the resulting binary is
exactly the same, although it contains a parametrized shift instead of
hard-coded boundaries.
This commit is contained in:
Max Kellermann 2008-09-28 18:37:43 +02:00
parent 5b5e46f5ef
commit 88aaa6b759
1 changed files with 18 additions and 10 deletions
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28
src/pcm_utils.c
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@ -31,6 +31,20 @@ pcm_dither(void)
return (rand() & 511) - (rand() & 511);
}
/**
* Check if the value is within the range of the provided bit size,
* and caps it if necessary.
*/
static mpd_sint32
pcm_range(mpd_sint32 sample, unsigned bits)
{
if (mpd_unlikely(sample < (-1 << (bits - 1))))
return -1 << (bits - 1);
if (mpd_unlikely(sample >= (1 << (bits - 1))))
return (1 << (bits - 1)) - 1;
return sample;
}
void pcm_volumeChange(char *buffer, int bufferSize,
const struct audio_format *format,
int volume)
@ -55,8 +69,7 @@ void pcm_volumeChange(char *buffer, int bufferSize,
temp32 += pcm_dither();
temp32 += 500;
temp32 /= 1000;
*buffer16 = temp32 > 32767 ? 32767 :
(temp32 < -32768 ? -32768 : temp32);
*buffer16 = pcm_range(temp32, 16);
buffer16++;
bufferSize -= 2;
}
@ -68,8 +81,7 @@ void pcm_volumeChange(char *buffer, int bufferSize,
temp32 += pcm_dither();
temp32 += 500;
temp32 /= 1000;
*buffer8 = temp32 > 127 ? 127 :
(temp32 < -128 ? -128 : temp32);
*buffer8 = pcm_range(temp32, 8);
buffer8++;
bufferSize--;
}
@ -99,9 +111,7 @@ static void pcm_add(char *buffer1, const char *buffer2, size_t bufferSize1,
temp32 += pcm_dither();
temp32 += 500;
temp32 /= 1000;
*buffer16_1 =
temp32 > 32767 ? 32767 : (temp32 <
-32768 ? -32768 : temp32);
*buffer16_1 = pcm_range(temp32, 16);
buffer16_1++;
buffer16_2++;
bufferSize1 -= 2;
@ -117,9 +127,7 @@ static void pcm_add(char *buffer1, const char *buffer2, size_t bufferSize1,
temp32 += pcm_dither();
temp32 += 500;
temp32 /= 1000;
*buffer8_1 =
temp32 > 127 ? 127 : (temp32 <
-128 ? -128 : temp32);
*buffer8_1 = pcm_range(temp32, 8);
buffer8_1++;
buffer8_2++;
bufferSize1--;