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dsd2pcm: move the bit reversing code to a generic library

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Instead of doing run-time initialisation, use a constant lookup table.
This commit is contained in:
Max Kellermann
2012-03-21 08:44:43 +01:00
parent 08ce24ec3f
commit c1d0a8b5ce
4 changed files with 73 additions and 8 deletions
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12
src/dsd2pcm/dsd2pcm.c
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@@ -1,3 +1,5 @@
#include "util/bit_reverse.h"
#include <stdlib.h>
#include <string.h>
@@ -84,7 +86,6 @@ static const double htaps[HTAPS] = {
};
static float ctables[CTABLES][256];
static unsigned char bitreverse[256];
static int precalculated = 0;
static void precalc(void)
@@ -92,11 +93,6 @@ static void precalc(void)
int t, e, m, k;
double acc;
if (precalculated) return;
for (t=0, e=0; t<256; ++t) {
bitreverse[t] = e;
for (m=128; m && !((e^=m)&m); m>>=1)
;
}
for (t=0; t<CTABLES; ++t) {
k = HTAPS - t*8;
if (k>8) k=8;
@@ -170,10 +166,10 @@ extern void dsd2pcm_translate(
lsbf = lsbf ? 1 : 0;
while (samples-- > 0) {
bite1 = *src & 0xFFu;
if (lsbf) bite1 = bitreverse[bite1];
if (lsbf) bite1 = bit_reverse(bite1);
ptr->fifo[ffp] = bite1; src += src_stride;
p = ptr->fifo + ((ffp-CTABLES) & FIFOMASK);
*p = bitreverse[*p & 0xFF];
*p = bit_reverse(*p);
acc = 0;
for (i=0; i<CTABLES; ++i) {
bite1 = ptr->fifo[(ffp -i) & FIFOMASK] & 0xFF;