SDL_audiocvt.c
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/*
SDL - Simple DirectMedia Layer
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Copyright (C) 1997-2006 Sam Lantinga
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library 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
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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Sam Lantinga
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slouken@libsdl.org
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*/
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#include "SDL_config.h"
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/* Functions for audio drivers to perform runtime conversion of audio format */
#include "SDL_audio.h"
/* Effectively mix right and left channels into a single channel */
void SDL_ConvertMono(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
Sint32 sample;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting to mono\n");
#endif
switch (format&0x8018) {
case AUDIO_U8: {
Uint8 *src, *dst;
src = cvt->buf;
dst = cvt->buf;
for ( i=cvt->len_cvt/2; i; --i ) {
sample = src[0] + src[1];
if ( sample > 255 ) {
*dst = 255;
} else {
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*dst = (Uint8)sample;
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}
src += 2;
dst += 1;
}
}
break;
case AUDIO_S8: {
Sint8 *src, *dst;
src = (Sint8 *)cvt->buf;
dst = (Sint8 *)cvt->buf;
for ( i=cvt->len_cvt/2; i; --i ) {
sample = src[0] + src[1];
if ( sample > 127 ) {
*dst = 127;
} else
if ( sample < -128 ) {
*dst = -128;
} else {
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*dst = (Sint8)sample;
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}
src += 2;
dst += 1;
}
}
break;
case AUDIO_U16: {
Uint8 *src, *dst;
src = cvt->buf;
dst = cvt->buf;
if ( (format & 0x1000) == 0x1000 ) {
for ( i=cvt->len_cvt/4; i; --i ) {
sample = (Uint16)((src[0]<<8)|src[1])+
(Uint16)((src[2]<<8)|src[3]);
if ( sample > 65535 ) {
dst[0] = 0xFF;
dst[1] = 0xFF;
} else {
dst[1] = (sample&0xFF);
sample >>= 8;
dst[0] = (sample&0xFF);
}
src += 4;
dst += 2;
}
} else {
for ( i=cvt->len_cvt/4; i; --i ) {
sample = (Uint16)((src[1]<<8)|src[0])+
(Uint16)((src[3]<<8)|src[2]);
if ( sample > 65535 ) {
dst[0] = 0xFF;
dst[1] = 0xFF;
} else {
dst[0] = (sample&0xFF);
sample >>= 8;
dst[1] = (sample&0xFF);
}
src += 4;
dst += 2;
}
}
}
break;
case AUDIO_S16: {
Uint8 *src, *dst;
src = cvt->buf;
dst = cvt->buf;
if ( (format & 0x1000) == 0x1000 ) {
for ( i=cvt->len_cvt/4; i; --i ) {
sample = (Sint16)((src[0]<<8)|src[1])+
(Sint16)((src[2]<<8)|src[3]);
if ( sample > 32767 ) {
dst[0] = 0x7F;
dst[1] = 0xFF;
} else
if ( sample < -32768 ) {
dst[0] = 0x80;
dst[1] = 0x00;
} else {
dst[1] = (sample&0xFF);
sample >>= 8;
dst[0] = (sample&0xFF);
}
src += 4;
dst += 2;
}
} else {
for ( i=cvt->len_cvt/4; i; --i ) {
sample = (Sint16)((src[1]<<8)|src[0])+
(Sint16)((src[3]<<8)|src[2]);
if ( sample > 32767 ) {
dst[1] = 0x7F;
dst[0] = 0xFF;
} else
if ( sample < -32768 ) {
dst[1] = 0x80;
dst[0] = 0x00;
} else {
dst[0] = (sample&0xFF);
sample >>= 8;
dst[1] = (sample&0xFF);
}
src += 4;
dst += 2;
}
}
}
break;
}
cvt->len_cvt /= 2;
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
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/* Discard top 4 channels */
void SDL_ConvertStrip(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
Sint32 lsample, rsample;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting down to stereo\n");
#endif
switch (format&0x8018) {
case AUDIO_U8: {
Uint8 *src, *dst;
src = cvt->buf;
dst = cvt->buf;
for ( i=cvt->len_cvt/6; i; --i ) {
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dst[0] = src[0];
dst[1] = src[1];
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src += 6;
dst += 2;
}
}
break;
case AUDIO_S8: {
Sint8 *src, *dst;
src = (Sint8 *)cvt->buf;
dst = (Sint8 *)cvt->buf;
for ( i=cvt->len_cvt/6; i; --i ) {
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dst[0] = src[0];
dst[1] = src[1];
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src += 6;
dst += 2;
}
}
break;
case AUDIO_U16: {
Uint8 *src, *dst;
src = cvt->buf;
dst = cvt->buf;
if ( (format & 0x1000) == 0x1000 ) {
for ( i=cvt->len_cvt/12; i; --i ) {
lsample = (Uint16)((src[0]<<8)|src[1]);
rsample = (Uint16)((src[2]<<8)|src[3]);
dst[1] = (lsample&0xFF);
lsample >>= 8;
dst[0] = (lsample&0xFF);
dst[3] = (rsample&0xFF);
rsample >>= 8;
dst[2] = (rsample&0xFF);
src += 12;
dst += 4;
}
} else {
for ( i=cvt->len_cvt/12; i; --i ) {
lsample = (Uint16)((src[1]<<8)|src[0]);
rsample = (Uint16)((src[3]<<8)|src[2]);
dst[0] = (lsample&0xFF);
lsample >>= 8;
dst[1] = (lsample&0xFF);
dst[2] = (rsample&0xFF);
rsample >>= 8;
dst[3] = (rsample&0xFF);
src += 12;
dst += 4;
}
}
}
break;
case AUDIO_S16: {
Uint8 *src, *dst;
src = cvt->buf;
dst = cvt->buf;
if ( (format & 0x1000) == 0x1000 ) {
for ( i=cvt->len_cvt/12; i; --i ) {
lsample = (Sint16)((src[0]<<8)|src[1]);
rsample = (Sint16)((src[2]<<8)|src[3]);
dst[1] = (lsample&0xFF);
lsample >>= 8;
dst[0] = (lsample&0xFF);
dst[3] = (rsample&0xFF);
rsample >>= 8;
dst[2] = (rsample&0xFF);
src += 12;
dst += 4;
}
} else {
for ( i=cvt->len_cvt/12; i; --i ) {
lsample = (Sint16)((src[1]<<8)|src[0]);
rsample = (Sint16)((src[3]<<8)|src[2]);
dst[0] = (lsample&0xFF);
lsample >>= 8;
dst[1] = (lsample&0xFF);
dst[2] = (rsample&0xFF);
rsample >>= 8;
dst[3] = (rsample&0xFF);
src += 12;
dst += 4;
}
}
}
break;
}
cvt->len_cvt /= 3;
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
/* Discard top 2 channels of 6 */
void SDL_ConvertStrip_2(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
Sint32 lsample, rsample;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting 6 down to quad\n");
#endif
switch (format&0x8018) {
case AUDIO_U8: {
Uint8 *src, *dst;
src = cvt->buf;
dst = cvt->buf;
for ( i=cvt->len_cvt/4; i; --i ) {
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dst[0] = src[0];
dst[1] = src[1];
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src += 4;
dst += 2;
}
}
break;
case AUDIO_S8: {
Sint8 *src, *dst;
src = (Sint8 *)cvt->buf;
dst = (Sint8 *)cvt->buf;
for ( i=cvt->len_cvt/4; i; --i ) {
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dst[0] = src[0];
dst[1] = src[1];
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src += 4;
dst += 2;
}
}
break;
case AUDIO_U16: {
Uint8 *src, *dst;
src = cvt->buf;
dst = cvt->buf;
if ( (format & 0x1000) == 0x1000 ) {
for ( i=cvt->len_cvt/8; i; --i ) {
lsample = (Uint16)((src[0]<<8)|src[1]);
rsample = (Uint16)((src[2]<<8)|src[3]);
dst[1] = (lsample&0xFF);
lsample >>= 8;
dst[0] = (lsample&0xFF);
dst[3] = (rsample&0xFF);
rsample >>= 8;
dst[2] = (rsample&0xFF);
src += 8;
dst += 4;
}
} else {
for ( i=cvt->len_cvt/8; i; --i ) {
lsample = (Uint16)((src[1]<<8)|src[0]);
rsample = (Uint16)((src[3]<<8)|src[2]);
dst[0] = (lsample&0xFF);
lsample >>= 8;
dst[1] = (lsample&0xFF);
dst[2] = (rsample&0xFF);
rsample >>= 8;
dst[3] = (rsample&0xFF);
src += 8;
dst += 4;
}
}
}
break;
case AUDIO_S16: {
Uint8 *src, *dst;
src = cvt->buf;
dst = cvt->buf;
if ( (format & 0x1000) == 0x1000 ) {
for ( i=cvt->len_cvt/8; i; --i ) {
lsample = (Sint16)((src[0]<<8)|src[1]);
rsample = (Sint16)((src[2]<<8)|src[3]);
dst[1] = (lsample&0xFF);
lsample >>= 8;
dst[0] = (lsample&0xFF);
dst[3] = (rsample&0xFF);
rsample >>= 8;
dst[2] = (rsample&0xFF);
src += 8;
dst += 4;
}
} else {
for ( i=cvt->len_cvt/8; i; --i ) {
lsample = (Sint16)((src[1]<<8)|src[0]);
rsample = (Sint16)((src[3]<<8)|src[2]);
dst[0] = (lsample&0xFF);
lsample >>= 8;
dst[1] = (lsample&0xFF);
dst[2] = (rsample&0xFF);
rsample >>= 8;
dst[3] = (rsample&0xFF);
src += 8;
dst += 4;
}
}
}
break;
}
cvt->len_cvt /= 2;
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
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/* Duplicate a mono channel to both stereo channels */
void SDL_ConvertStereo(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting to stereo\n");
#endif
if ( (format & 0xFF) == 16 ) {
Uint16 *src, *dst;
src = (Uint16 *)(cvt->buf+cvt->len_cvt);
dst = (Uint16 *)(cvt->buf+cvt->len_cvt*2);
for ( i=cvt->len_cvt/2; i; --i ) {
dst -= 2;
src -= 1;
dst[0] = src[0];
dst[1] = src[0];
}
} else {
Uint8 *src, *dst;
src = cvt->buf+cvt->len_cvt;
dst = cvt->buf+cvt->len_cvt*2;
for ( i=cvt->len_cvt; i; --i ) {
dst -= 2;
src -= 1;
dst[0] = src[0];
dst[1] = src[0];
}
}
cvt->len_cvt *= 2;
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
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/* Duplicate a stereo channel to a pseudo-5.1 stream */
void SDL_ConvertSurround(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting stereo to surround\n");
#endif
switch (format&0x8018) {
case AUDIO_U8: {
Uint8 *src, *dst, lf, rf, ce;
src = (Uint8 *)(cvt->buf+cvt->len_cvt);
dst = (Uint8 *)(cvt->buf+cvt->len_cvt*3);
for ( i=cvt->len_cvt; i; --i ) {
dst -= 6;
src -= 2;
lf = src[0];
rf = src[1];
ce = (lf/2) + (rf/2);
dst[0] = lf;
dst[1] = rf;
dst[2] = lf - ce;
dst[3] = rf - ce;
dst[4] = ce;
dst[5] = ce;
}
}
break;
case AUDIO_S8: {
Sint8 *src, *dst, lf, rf, ce;
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src = (Sint8 *)cvt->buf+cvt->len_cvt;
dst = (Sint8 *)cvt->buf+cvt->len_cvt*3;
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for ( i=cvt->len_cvt; i; --i ) {
dst -= 6;
src -= 2;
lf = src[0];
rf = src[1];
ce = (lf/2) + (rf/2);
dst[0] = lf;
dst[1] = rf;
dst[2] = lf - ce;
dst[3] = rf - ce;
dst[4] = ce;
dst[5] = ce;
}
}
break;
case AUDIO_U16: {
Uint8 *src, *dst;
Uint16 lf, rf, ce, lr, rr;
src = cvt->buf+cvt->len_cvt;
dst = cvt->buf+cvt->len_cvt*3;
if ( (format & 0x1000) == 0x1000 ) {
for ( i=cvt->len_cvt/4; i; --i ) {
dst -= 12;
src -= 4;
lf = (Uint16)((src[0]<<8)|src[1]);
rf = (Uint16)((src[2]<<8)|src[3]);
ce = (lf/2) + (rf/2);
rr = lf - ce;
lr = rf - ce;
dst[1] = (lf&0xFF);
dst[0] = ((lf>>8)&0xFF);
dst[3] = (rf&0xFF);
dst[2] = ((rf>>8)&0xFF);
dst[1+4] = (lr&0xFF);
dst[0+4] = ((lr>>8)&0xFF);
dst[3+4] = (rr&0xFF);
dst[2+4] = ((rr>>8)&0xFF);
dst[1+8] = (ce&0xFF);
dst[0+8] = ((ce>>8)&0xFF);
dst[3+8] = (ce&0xFF);
dst[2+8] = ((ce>>8)&0xFF);
}
} else {
for ( i=cvt->len_cvt/4; i; --i ) {
dst -= 12;
src -= 4;
lf = (Uint16)((src[1]<<8)|src[0]);
rf = (Uint16)((src[3]<<8)|src[2]);
ce = (lf/2) + (rf/2);
rr = lf - ce;
lr = rf - ce;
dst[0] = (lf&0xFF);
dst[1] = ((lf>>8)&0xFF);
dst[2] = (rf&0xFF);
dst[3] = ((rf>>8)&0xFF);
dst[0+4] = (lr&0xFF);
dst[1+4] = ((lr>>8)&0xFF);
dst[2+4] = (rr&0xFF);
dst[3+4] = ((rr>>8)&0xFF);
dst[0+8] = (ce&0xFF);
dst[1+8] = ((ce>>8)&0xFF);
dst[2+8] = (ce&0xFF);
dst[3+8] = ((ce>>8)&0xFF);
}
}
}
break;
case AUDIO_S16: {
Uint8 *src, *dst;
Sint16 lf, rf, ce, lr, rr;
src = cvt->buf+cvt->len_cvt;
dst = cvt->buf+cvt->len_cvt*3;
if ( (format & 0x1000) == 0x1000 ) {
for ( i=cvt->len_cvt/4; i; --i ) {
dst -= 12;
src -= 4;
lf = (Sint16)((src[0]<<8)|src[1]);
rf = (Sint16)((src[2]<<8)|src[3]);
ce = (lf/2) + (rf/2);
rr = lf - ce;
lr = rf - ce;
dst[1] = (lf&0xFF);
dst[0] = ((lf>>8)&0xFF);
dst[3] = (rf&0xFF);
dst[2] = ((rf>>8)&0xFF);
dst[1+4] = (lr&0xFF);
dst[0+4] = ((lr>>8)&0xFF);
dst[3+4] = (rr&0xFF);
dst[2+4] = ((rr>>8)&0xFF);
dst[1+8] = (ce&0xFF);
dst[0+8] = ((ce>>8)&0xFF);
dst[3+8] = (ce&0xFF);
dst[2+8] = ((ce>>8)&0xFF);
}
} else {
for ( i=cvt->len_cvt/4; i; --i ) {
dst -= 12;
src -= 4;
lf = (Sint16)((src[1]<<8)|src[0]);
rf = (Sint16)((src[3]<<8)|src[2]);
ce = (lf/2) + (rf/2);
rr = lf - ce;
lr = rf - ce;
dst[0] = (lf&0xFF);
dst[1] = ((lf>>8)&0xFF);
dst[2] = (rf&0xFF);
dst[3] = ((rf>>8)&0xFF);
dst[0+4] = (lr&0xFF);
dst[1+4] = ((lr>>8)&0xFF);
dst[2+4] = (rr&0xFF);
dst[3+4] = ((rr>>8)&0xFF);
dst[0+8] = (ce&0xFF);
dst[1+8] = ((ce>>8)&0xFF);
dst[2+8] = (ce&0xFF);
dst[3+8] = ((ce>>8)&0xFF);
}
}
}
break;
}
cvt->len_cvt *= 3;
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
/* Duplicate a stereo channel to a pseudo-4.0 stream */
void SDL_ConvertSurround_4(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting stereo to quad\n");
#endif
switch (format&0x8018) {
case AUDIO_U8: {
Uint8 *src, *dst, lf, rf, ce;
src = (Uint8 *)(cvt->buf+cvt->len_cvt);
dst = (Uint8 *)(cvt->buf+cvt->len_cvt*2);
for ( i=cvt->len_cvt; i; --i ) {
dst -= 4;
src -= 2;
lf = src[0];
rf = src[1];
ce = (lf/2) + (rf/2);
dst[0] = lf;
dst[1] = rf;
dst[2] = lf - ce;
dst[3] = rf - ce;
}
}
break;
case AUDIO_S8: {
Sint8 *src, *dst, lf, rf, ce;
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src = (Sint8 *)cvt->buf+cvt->len_cvt;
dst = (Sint8 *)cvt->buf+cvt->len_cvt*2;
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for ( i=cvt->len_cvt; i; --i ) {
dst -= 4;
src -= 2;
lf = src[0];
rf = src[1];
ce = (lf/2) + (rf/2);
dst[0] = lf;
dst[1] = rf;
dst[2] = lf - ce;
dst[3] = rf - ce;
}
}
break;
case AUDIO_U16: {
Uint8 *src, *dst;
Uint16 lf, rf, ce, lr, rr;
src = cvt->buf+cvt->len_cvt;
dst = cvt->buf+cvt->len_cvt*2;
if ( (format & 0x1000) == 0x1000 ) {
for ( i=cvt->len_cvt/4; i; --i ) {
dst -= 8;
src -= 4;
lf = (Uint16)((src[0]<<8)|src[1]);
rf = (Uint16)((src[2]<<8)|src[3]);
ce = (lf/2) + (rf/2);
rr = lf - ce;
lr = rf - ce;
dst[1] = (lf&0xFF);
dst[0] = ((lf>>8)&0xFF);
dst[3] = (rf&0xFF);
dst[2] = ((rf>>8)&0xFF);
dst[1+4] = (lr&0xFF);
dst[0+4] = ((lr>>8)&0xFF);
dst[3+4] = (rr&0xFF);
dst[2+4] = ((rr>>8)&0xFF);
}
} else {
for ( i=cvt->len_cvt/4; i; --i ) {
dst -= 8;
src -= 4;
lf = (Uint16)((src[1]<<8)|src[0]);
rf = (Uint16)((src[3]<<8)|src[2]);
ce = (lf/2) + (rf/2);
rr = lf - ce;
lr = rf - ce;
dst[0] = (lf&0xFF);
dst[1] = ((lf>>8)&0xFF);
dst[2] = (rf&0xFF);
dst[3] = ((rf>>8)&0xFF);
dst[0+4] = (lr&0xFF);
dst[1+4] = ((lr>>8)&0xFF);
dst[2+4] = (rr&0xFF);
dst[3+4] = ((rr>>8)&0xFF);
}
}
}
break;
case AUDIO_S16: {
Uint8 *src, *dst;
Sint16 lf, rf, ce, lr, rr;
src = cvt->buf+cvt->len_cvt;
dst = cvt->buf+cvt->len_cvt*2;
if ( (format & 0x1000) == 0x1000 ) {
for ( i=cvt->len_cvt/4; i; --i ) {
dst -= 8;
src -= 4;
lf = (Sint16)((src[0]<<8)|src[1]);
rf = (Sint16)((src[2]<<8)|src[3]);
ce = (lf/2) + (rf/2);
rr = lf - ce;
lr = rf - ce;
dst[1] = (lf&0xFF);
dst[0] = ((lf>>8)&0xFF);
dst[3] = (rf&0xFF);
dst[2] = ((rf>>8)&0xFF);
dst[1+4] = (lr&0xFF);
dst[0+4] = ((lr>>8)&0xFF);
dst[3+4] = (rr&0xFF);
dst[2+4] = ((rr>>8)&0xFF);
}
} else {
for ( i=cvt->len_cvt/4; i; --i ) {
dst -= 8;
src -= 4;
lf = (Sint16)((src[1]<<8)|src[0]);
rf = (Sint16)((src[3]<<8)|src[2]);
ce = (lf/2) + (rf/2);
rr = lf - ce;
lr = rf - ce;
dst[0] = (lf&0xFF);
dst[1] = ((lf>>8)&0xFF);
dst[2] = (rf&0xFF);
dst[3] = ((rf>>8)&0xFF);
dst[0+4] = (lr&0xFF);
dst[1+4] = ((lr>>8)&0xFF);
dst[2+4] = (rr&0xFF);
dst[3+4] = ((rr>>8)&0xFF);
}
}
}
break;
}
cvt->len_cvt *= 2;
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
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/* Convert 8-bit to 16-bit - LSB */
void SDL_Convert16LSB(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
Uint8 *src, *dst;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting to 16-bit LSB\n");
#endif
src = cvt->buf+cvt->len_cvt;
dst = cvt->buf+cvt->len_cvt*2;
for ( i=cvt->len_cvt; i; --i ) {
src -= 1;
dst -= 2;
dst[1] = *src;
dst[0] = 0;
}
format = ((format & ~0x0008) | AUDIO_U16LSB);
cvt->len_cvt *= 2;
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
/* Convert 8-bit to 16-bit - MSB */
void SDL_Convert16MSB(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
Uint8 *src, *dst;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting to 16-bit MSB\n");
#endif
src = cvt->buf+cvt->len_cvt;
dst = cvt->buf+cvt->len_cvt*2;
for ( i=cvt->len_cvt; i; --i ) {
src -= 1;
dst -= 2;
dst[0] = *src;
dst[1] = 0;
}
format = ((format & ~0x0008) | AUDIO_U16MSB);
cvt->len_cvt *= 2;
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
/* Convert 16-bit to 8-bit */
void SDL_Convert8(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
Uint8 *src, *dst;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting to 8-bit\n");
#endif
src = cvt->buf;
dst = cvt->buf;
if ( (format & 0x1000) != 0x1000 ) { /* Little endian */
++src;
}
for ( i=cvt->len_cvt/2; i; --i ) {
*dst = *src;
src += 2;
dst += 1;
}
format = ((format & ~0x9010) | AUDIO_U8);
cvt->len_cvt /= 2;
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
/* Toggle signed/unsigned */
void SDL_ConvertSign(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
Uint8 *data;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting audio signedness\n");
#endif
data = cvt->buf;
if ( (format & 0xFF) == 16 ) {
if ( (format & 0x1000) != 0x1000 ) { /* Little endian */
++data;
}
for ( i=cvt->len_cvt/2; i; --i ) {
*data ^= 0x80;
data += 2;
}
} else {
for ( i=cvt->len_cvt; i; --i ) {
*data++ ^= 0x80;
}
}
format = (format ^ 0x8000);
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
/* Toggle endianness */
void SDL_ConvertEndian(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
Uint8 *data, tmp;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting audio endianness\n");
#endif
data = cvt->buf;
for ( i=cvt->len_cvt/2; i; --i ) {
tmp = data[0];
data[0] = data[1];
data[1] = tmp;
data += 2;
}
format = (format ^ 0x1000);
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
/* Convert rate up by multiple of 2 */
void SDL_RateMUL2(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
Uint8 *src, *dst;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting audio rate * 2\n");
#endif
src = cvt->buf+cvt->len_cvt;
dst = cvt->buf+cvt->len_cvt*2;
switch (format & 0xFF) {
case 8:
for ( i=cvt->len_cvt; i; --i ) {
src -= 1;
dst -= 2;
dst[0] = src[0];
dst[1] = src[0];
}
break;
case 16:
for ( i=cvt->len_cvt/2; i; --i ) {
src -= 2;
dst -= 4;
dst[0] = src[0];
dst[1] = src[1];
dst[2] = src[0];
dst[3] = src[1];
}
break;
}
cvt->len_cvt *= 2;
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
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/* Convert rate up by multiple of 2, for stereo */
void SDL_RateMUL2_c2(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
Uint8 *src, *dst;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting audio rate * 2\n");
#endif
src = cvt->buf+cvt->len_cvt;
dst = cvt->buf+cvt->len_cvt*2;
switch (format & 0xFF) {
case 8:
for ( i=cvt->len_cvt/2; i; --i ) {
src -= 2;
dst -= 4;
dst[0] = src[0];
dst[1] = src[1];
dst[2] = src[0];
dst[3] = src[1];
}
break;
case 16:
for ( i=cvt->len_cvt/4; i; --i ) {
src -= 4;
dst -= 8;
dst[0] = src[0];
dst[1] = src[1];
dst[2] = src[2];
dst[3] = src[3];
dst[4] = src[0];
dst[5] = src[1];
dst[6] = src[2];
dst[7] = src[3];
}
break;
}
cvt->len_cvt *= 2;
if ( cvt->filters[++cvt->filter_index] ) {
cvt->filters[cvt->filter_index](cvt, format);
}
}
/* Convert rate up by multiple of 2, for quad */
void SDL_RateMUL2_c4(SDL_AudioCVT *cvt, Uint16 format)
{
int i;
Uint8 *src, *dst;
#ifdef DEBUG_CONVERT
fprintf(stderr, "Converting audio rate * 2\n");
#endif
src = cvt->buf+cvt->len_cvt;
dst = cvt->buf+cvt->len_cvt*2;
switch (format & 0xFF) {
case 8:
for ( i=cvt->len_cvt/4; i; --i ) {
src -= 4;
dst -= 8;
dst[0] = src[0];
dst[1] = src[1];
dst[2] = src[2];
dst[3] = src[3];
dst[4] = src[0];
dst[5] = src[1];
dst[6] = src[2];
dst[7] = src[3];
}
break;