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/*
* Direct Stream Digital (DSD) decoder
* based on BSD licensed dsd2pcm by Sebastian Gesemann
* Copyright (c) 2009, 2011 Sebastian Gesemann. All rights reserved.
* Copyright (c) 2014 Peter Ross
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavcodec/internal.h"
#include "libavcodec/mathops.h"
#include "avcodec.h"
#include "dsd_tablegen.h"
#include "dsd.h"
static av_cold void dsd_ctables_tableinit(void)
{
int t, e, m, sign;
double acc[CTABLES];
for (e = 0; e < 256; ++e) {
memset(acc, 0, sizeof(acc));
for (m = 0; m < 8; ++m) {
sign = (((e >> (7 - m)) & 1) * 2 - 1);
for (t = 0; t < CTABLES; ++t)
acc[t] += sign * htaps[t * 8 + m];
}
for (t = 0; t < CTABLES; ++t)
ctables[CTABLES - 1 - t][e] = acc[t];
}
}
av_cold void ff_init_dsd_data(void)
{
static int done = 0;
if (done)
return;
dsd_ctables_tableinit();
done = 1;
}
void ff_dsd2pcm_translate(DSDContext* s, size_t samples, int lsbf,
const uint8_t *src, ptrdiff_t src_stride,
float *dst, ptrdiff_t dst_stride)
{
uint8_t buf[FIFOSIZE];
unsigned pos, i;
uint8_t* p;
double sum;
pos = s->pos;
memcpy(buf, s->buf, sizeof(buf));
while (samples-- > 0) {
buf[pos] = lsbf ? ff_reverse[*src] : *src;
src += src_stride;
p = buf + ((pos - CTABLES) & FIFOMASK);
*p = ff_reverse[*p];
sum = 0.0;
for (i = 0; i < CTABLES; i++) {
uint8_t a = buf[(pos - i) & FIFOMASK];
uint8_t b = buf[(pos - (CTABLES*2 - 1) + i) & FIFOMASK];
sum += ctables[i][a] + ctables[i][b];
}
*dst = (float)sum;
dst += dst_stride;
pos = (pos + 1) & FIFOMASK;
}
s->pos = pos;
memcpy(s->buf, buf, sizeof(buf));
}
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