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authorMax Kellermann <max@duempel.org>2008-09-28 18:37:43 +0200
committerEric Wong <normalperson@yhbt.net>2008-09-29 01:28:45 -0700
commit33df4c65594384c32f91f0445d80fb2453d5ff7a (patch)
treeebd0be82a11f2f835f2ed7f51a4a36300d9f590e
parentf471b4cfc5e4ad42e34f79daa81a2de217134517 (diff)
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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.
-rw-r--r--src/pcm_utils.c28
1 files changed, 18 insertions, 10 deletions
diff --git a/src/pcm_utils.c b/src/pcm_utils.c
index 3eb24d882..077010062 100644
--- a/src/pcm_utils.c
+++ b/src/pcm_utils.c
@@ -30,6 +30,20 @@ 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 AudioFormat * format,
int volume)
{
@@ -53,8 +67,7 @@ void pcm_volumeChange(char *buffer, int bufferSize, const AudioFormat * format,
temp32 += pcm_dither();
temp32 += 500;
temp32 /= 1000;
- *buffer16 = temp32 > 32767 ? 32767 :
- (temp32 < -32768 ? -32768 : temp32);
+ *buffer16 = pcm_range(temp32, 16);
buffer16++;
bufferSize -= 2;
}
@@ -66,8 +79,7 @@ void pcm_volumeChange(char *buffer, int bufferSize, const AudioFormat * format,
temp32 += pcm_dither();
temp32 += 500;
temp32 /= 1000;
- *buffer8 = temp32 > 127 ? 127 :
- (temp32 < -128 ? -128 : temp32);
+ *buffer8 = pcm_range(temp32, 8);
buffer8++;
bufferSize--;
}
@@ -97,9 +109,7 @@ 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;
@@ -115,9 +125,7 @@ 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--;