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minor optimizations

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This commit is contained in:
Josh Coalson 2007-01-24 04:23:53 +00:00
parent 92e43175e3
commit f5dd47832d
1 changed files with 37 additions and 28 deletions
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65
src/libFLAC/fixed.c
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@ -34,6 +34,7 @@
#endif
#include <math.h>
#include <string.h>
#include "private/bitmath.h"
#include "private/fixed.h"
#include "FLAC/assert.h"
@ -355,32 +356,36 @@ void FLAC__fixed_compute_residual(const FLAC__int32 data[], unsigned data_len, u
switch(order) {
case 0:
for(i = 0; i < idata_len; i++) {
residual[i] = data[i];
}
FLAC__ASSERT(sizeof(residual[0]) == sizeof(data[0]));
memcpy(residual, data, sizeof(residual[0])*data_len);
break;
case 1:
for(i = 0; i < idata_len; i++) {
for(i = 0; i < idata_len; i++)
residual[i] = data[i] - data[i-1];
}
break;
case 2:
for(i = 0; i < idata_len; i++) {
/* == data[i] - 2*data[i-1] + data[i-2] */
for(i = 0; i < idata_len; i++)
#if 1 /* OPT: may be faster with some compilers on some systems */
residual[i] = data[i] - (data[i-1] << 1) + data[i-2];
}
#else
residual[i] = data[i] - 2*data[i-1] + data[i-2];
#endif
break;
case 3:
for(i = 0; i < idata_len; i++) {
/* == data[i] - 3*data[i-1] + 3*data[i-2] - data[i-3] */
for(i = 0; i < idata_len; i++)
#if 1 /* OPT: may be faster with some compilers on some systems */
residual[i] = data[i] - (((data[i-1]-data[i-2])<<1) + (data[i-1]-data[i-2])) - data[i-3];
}
#else
residual[i] = data[i] - 3*data[i-1] + 3*data[i-2] - data[i-3];
#endif
break;
case 4:
for(i = 0; i < idata_len; i++) {
/* == data[i] - 4*data[i-1] + 6*data[i-2] - 4*data[i-3] + data[i-4] */
for(i = 0; i < idata_len; i++)
#if 1 /* OPT: may be faster with some compilers on some systems */
residual[i] = data[i] - ((data[i-1]+data[i-3])<<2) + ((data[i-2]<<2) + (data[i-2]<<1)) + data[i-4];
}
#else
residual[i] = data[i] - 4*data[i-1] + 6*data[i-2] - 4*data[i-3] + data[i-4];
#endif
break;
default:
FLAC__ASSERT(0);
@ -393,32 +398,36 @@ void FLAC__fixed_restore_signal(const FLAC__int32 residual[], unsigned data_len,
switch(order) {
case 0:
for(i = 0; i < idata_len; i++) {
data[i] = residual[i];
}
FLAC__ASSERT(sizeof(residual[0]) == sizeof(data[0]));
memcpy(data, residual, sizeof(residual[0])*data_len);
break;
case 1:
for(i = 0; i < idata_len; i++) {
for(i = 0; i < idata_len; i++)
data[i] = residual[i] + data[i-1];
}
break;
case 2:
for(i = 0; i < idata_len; i++) {
/* == residual[i] + 2*data[i-1] - data[i-2] */
for(i = 0; i < idata_len; i++)
#if 1 /* OPT: may be faster with some compilers on some systems */
data[i] = residual[i] + (data[i-1]<<1) - data[i-2];
}
#else
data[i] = residual[i] + 2*data[i-1] - data[i-2];
#endif
break;
case 3:
for(i = 0; i < idata_len; i++) {
/* residual[i] + 3*data[i-1] - 3*data[i-2]) + data[i-3] */
for(i = 0; i < idata_len; i++)
#if 1 /* OPT: may be faster with some compilers on some systems */
data[i] = residual[i] + (((data[i-1]-data[i-2])<<1) + (data[i-1]-data[i-2])) + data[i-3];
}
#else
data[i] = residual[i] + 3*data[i-1] - 3*data[i-2] + data[i-3];
#endif
break;
case 4:
for(i = 0; i < idata_len; i++) {
/* == residual[i] + 4*data[i-1] - 6*data[i-2] + 4*data[i-3] - data[i-4] */
for(i = 0; i < idata_len; i++)
#if 1 /* OPT: may be faster with some compilers on some systems */
data[i] = residual[i] + ((data[i-1]+data[i-3])<<2) - ((data[i-2]<<2) + (data[i-2]<<1)) - data[i-4];
}
#else
data[i] = residual[i] + 4*data[i-1] - 6*data[i-2] + 4*data[i-3] - data[i-4];
#endif
break;
default:
FLAC__ASSERT(0);