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#include <stdlib.h>
#include <string.h>
#include "dsl.h"
#include "util.h"
#include "SDL.h"
#include "SDL_mixer.h"
extern volatile int MV_MixPage;
static int DSL_ErrorCode = DSL_Ok;
static int mixer_initialized;
static void ( *_CallBackFunc )( void );
static volatile char *_BufferStart;
static int _BufferSize;
static int _NumDivisions;
static int _SampleRate;
static int _remainder;
static Mix_Chunk *blank;
static unsigned char *blank_buf;
/*
possible todo ideas: cache sdl/sdl mixer error messages.
*/
char *DSL_ErrorString( int ErrorNumber )
{
char *ErrorString;
switch (ErrorNumber) {
case DSL_Warning:
case DSL_Error:
ErrorString = DSL_ErrorString(DSL_ErrorCode);
break;
case DSL_Ok:
ErrorString = "SDL Driver ok.";
break;
case DSL_SDLInitFailure:
ErrorString = "SDL Audio initialization failed.";
break;
case DSL_MixerActive:
ErrorString = "SDL Mixer already initialized.";
break;
case DSL_MixerInitFailure:
ErrorString = "SDL Mixer initialization failed.";
break;
default:
ErrorString = "Unknown SDL Driver error.";
break;
}
return ErrorString;
}
static void DSL_SetErrorCode(int ErrorCode)
{
DSL_ErrorCode = ErrorCode;
}
int DSL_Init( void )
{
DSL_SetErrorCode(DSL_Ok);
if (SDL_InitSubSystem(SDL_INIT_AUDIO|SDL_INIT_NOPARACHUTE) < 0) {
DSL_SetErrorCode(DSL_SDLInitFailure);
return DSL_Error;
}
return DSL_Ok;
}
void DSL_Shutdown( void )
{
DSL_StopPlayback();
}
static void mixer_callback(int chan, void *stream, int len, void *udata)
{
Uint8 *stptr;
Uint8 *fxptr;
int copysize;
/* len should equal _BufferSize, else this is screwed up */
stptr = (Uint8 *)stream;
if (_remainder > 0) {
copysize = min(len, _remainder);
fxptr = (Uint8 *)(&_BufferStart[MV_MixPage *
_BufferSize]);
memcpy(stptr, fxptr+(_BufferSize-_remainder), copysize);
len -= copysize;
_remainder -= copysize;
stptr += copysize;
}
while (len > 0) {
/* new buffer */
_CallBackFunc();
fxptr = (Uint8 *)(&_BufferStart[MV_MixPage *
_BufferSize]);
copysize = min(len, _BufferSize);
memcpy(stptr, fxptr, copysize);
len -= copysize;
stptr += copysize;
}
_remainder = len;
}
int DSL_BeginBufferedPlayback( char *BufferStart,
int BufferSize, int NumDivisions, unsigned SampleRate,
int MixMode, void ( *CallBackFunc )( void ) )
{
Uint16 format;
int channels;
int chunksize;
int blah;
if (mixer_initialized) {
DSL_SetErrorCode(DSL_MixerActive);
return DSL_Error;
}
_CallBackFunc = CallBackFunc;
_BufferStart = BufferStart;
_BufferSize = (BufferSize / NumDivisions);
_NumDivisions = NumDivisions;
_SampleRate = SampleRate;
_remainder = 0;
format = (MixMode & SIXTEEN_BIT) ? AUDIO_S16LSB : AUDIO_U8;
channels = (MixMode & STEREO) ? 2 : 1;
/*
I find 50ms to be ideal, at least with my hardware. This clamping mechanism
was added because it seems the above remainder handling isn't so nice --kode54
*/
chunksize = (5 * SampleRate) / 100;
blah = _BufferSize;
if (MixMode & SIXTEEN_BIT) blah >>= 1;
if (MixMode & STEREO) blah >>= 1;
if (chunksize % blah) chunksize += blah - (chunksize % blah);
if (Mix_OpenAudio(SampleRate, format, channels, chunksize) < 0) {
DSL_SetErrorCode(DSL_MixerInitFailure);
return DSL_Error;
}
/*
Mix_SetPostMix(mixer_callback, NULL);
*/
/* have to use a channel because postmix will overwrite the music... */
Mix_RegisterEffect(0, mixer_callback, NULL, NULL);
/* create a dummy sample just to allocate that channel */
blank_buf = (Uint8 *)malloc(4096);
memset(blank_buf, 0, 4096);
blank = Mix_QuickLoad_RAW(blank_buf, 4096);
Mix_PlayChannel(0, blank, -1);
mixer_initialized = 1;
return DSL_Ok;
}
void DSL_StopPlayback( void )
{
if (mixer_initialized) {
Mix_HaltChannel(0);
}
if (blank != NULL) {
Mix_FreeChunk(blank);
}
blank = NULL;
if (blank_buf != NULL) {
free(blank_buf);
}
blank_buf = NULL;
if (mixer_initialized) {
Mix_CloseAudio();
}
mixer_initialized = 0;
}
unsigned DSL_GetPlaybackRate( void )
{
return _SampleRate;
}
uint32_t DisableInterrupts( void )
{
return 0;
}
void RestoreInterrupts( uint32_t flags )
{
}
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