This repository has been archived by the owner on Feb 11, 2021. It is now read-only.
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 */
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void SDLCALL
SDL_ConvertMono (SDL_AudioCVT * cvt, Uint16 format)
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int i;
Sint32 sample;
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#ifdef DEBUG_CONVERT
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fprintf (stderr, "Converting to mono\n");
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#endif
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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 {
*dst = (Uint8) sample;
}
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 {
*dst = (Sint8) sample;
}
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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}
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/* Discard top 4 channels */
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void SDLCALL
SDL_ConvertStrip (SDL_AudioCVT * cvt, Uint16 format)
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int i;
Sint32 lsample, rsample;
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#ifdef DEBUG_CONVERT
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fprintf (stderr, "Converting down to stereo\n");
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switch (format & 0x8018) {
case AUDIO_U8:
{
Uint8 *src, *dst;
src = cvt->buf;
dst = cvt->buf;
for (i = cvt->len_cvt / 6; i; --i) {
dst[0] = src[0];
dst[1] = src[1];
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) {
dst[0] = src[0];
dst[1] = src[1];
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);
}
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}
/* Discard top 2 channels of 6 */
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void SDLCALL
SDL_ConvertStrip_2 (SDL_AudioCVT * cvt, Uint16 format)
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int i;
Sint32 lsample, rsample;
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#ifdef DEBUG_CONVERT
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fprintf (stderr, "Converting 6 down to quad\n");
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switch (format & 0x8018) {
case AUDIO_U8:
{
Uint8 *src, *dst;
src = cvt->buf;
dst = cvt->buf;
for (i = cvt->len_cvt / 4; i; --i) {
dst[0] = src[0];
dst[1] = src[1];
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) {
dst[0] = src[0];
dst[1] = src[1];
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 */
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void SDLCALL
SDL_ConvertStereo (SDL_AudioCVT * cvt, Uint16 format)
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{
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#ifdef DEBUG_CONVERT
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fprintf (stderr, "Converting to stereo\n");
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#endif
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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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}
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/* Duplicate a stereo channel to a pseudo-5.1 stream */
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void SDLCALL
SDL_ConvertSurround (SDL_AudioCVT * cvt, Uint16 format)
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#ifdef DEBUG_CONVERT
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fprintf (stderr, "Converting stereo to surround\n");
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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;
src = (Sint8 *) cvt->buf + cvt->len_cvt;
dst = (Sint8 *) 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_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);
}
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}
/* Duplicate a stereo channel to a pseudo-4.0 stream */
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void SDLCALL
SDL_ConvertSurround_4 (SDL_AudioCVT * cvt, Uint16 format)
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#ifdef DEBUG_CONVERT
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fprintf (stderr, "Converting stereo to quad\n");
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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;
src = (Sint8 *) cvt->buf + cvt->len_cvt;
dst = (Sint8 *) 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_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);
}
793
/* Convert 8-bit to 16-bit - LSB */
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795
void SDLCALL
SDL_Convert16LSB (SDL_AudioCVT * cvt, Uint16 format)
796
{
797
798
int i;
Uint8 *src, *dst;
799
800
#ifdef DEBUG_CONVERT
801
fprintf (stderr, "Converting to 16-bit LSB\n");
802
#endif
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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);
}
816
}
818
/* Convert 8-bit to 16-bit - MSB */
819
820
void SDLCALL
SDL_Convert16MSB (SDL_AudioCVT * cvt, Uint16 format)
821
{
822
823
int i;
Uint8 *src, *dst;
824
825
#ifdef DEBUG_CONVERT
826
fprintf (stderr, "Converting to 16-bit MSB\n");
827
#endif
828
829
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831
832
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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);
}
841
842
843
}
/* Convert 16-bit to 8-bit */
844
845
void SDLCALL
SDL_Convert8 (SDL_AudioCVT * cvt, Uint16 format)
846
{
847
848
int i;
Uint8 *src, *dst;
849
850
#ifdef DEBUG_CONVERT
851
fprintf (stderr, "Converting to 8-bit\n");
852
#endif
853
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859
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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);
}
868
869
870
}
/* Toggle signed/unsigned */
871
872
void SDLCALL
SDL_ConvertSign (SDL_AudioCVT * cvt, Uint16 format)
873
{
874
875
int i;
Uint8 *data;
876
877
#ifdef DEBUG_CONVERT
878
fprintf (stderr, "Converting audio signedness\n");
879
#endif
880
881
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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);
}
898
899
900
}
/* Toggle endianness */
901
902
void SDLCALL
SDL_ConvertEndian (SDL_AudioCVT * cvt, Uint16 format)
903
{
904
905
int i;
Uint8 *data, tmp;
906
907
#ifdef DEBUG_CONVERT
908
fprintf (stderr, "Converting audio endianness\n");
909
#endif
910
911
912
913
914
915
916
917
918
919
920
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);
}
921
922
923
}
/* Convert rate up by multiple of 2 */
924
925
void SDLCALL
SDL_RateMUL2 (SDL_AudioCVT * cvt, Uint16 format)
926
{
927
928
int i;
Uint8 *src, *dst;
929
930
#ifdef DEBUG_CONVERT
931
fprintf (stderr, "Converting audio rate * 2\n");
932
#endif
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
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958
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);
}
959
960
}
961
962
/* Convert rate up by multiple of 2, for stereo */
963
964
void SDLCALL
SDL_RateMUL2_c2 (SDL_AudioCVT * cvt, Uint16 format)
966
967
int i;
Uint8 *src, *dst;
968
969
#ifdef DEBUG_CONVERT
970
fprintf (stderr, "Converting audio rate * 2\n");
972
973
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975
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978
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980
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987
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999
1000
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;