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atari: Do not use system interrupt for handling audio. Do it from use…
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…rspace, like RISCOS backend.
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@pmandin
pmandin committed Jul 28, 2014
1 parent f202686 commit f032668
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Showing 9 changed files with 269 additions and 577 deletions.
179 changes: 130 additions & 49 deletions src/audio/mint/SDL_mintaudio.c
View file
Expand Up @@ -35,54 +35,154 @@
#include <mint/cookie.h>

#include "SDL_audio.h"
#include "../SDL_audio_c.h"
#include "../SDL_sysaudio.h"

#include "../../video/ataricommon/SDL_atarimxalloc_c.h"

#include "SDL_mintaudio.h"
#include "SDL_mintaudio_stfa.h"

/* The audio device */

#define MAX_DMA_BUF 8

SDL_AudioDevice *SDL_MintAudio_device;
Uint8 *SDL_MintAudio_audiobuf[2]; /* Pointers to buffers */
unsigned long SDL_MintAudio_audiosize; /* Length of audio buffer=spec->size */
volatile unsigned short SDL_MintAudio_numbuf; /* Buffer to play */
volatile unsigned short SDL_MintAudio_mutex;
volatile unsigned long SDL_MintAudio_clocktics;
cookie_stfa_t *SDL_MintAudio_stfa;
unsigned short SDL_MintAudio_hasfpu;

static int SDL_MintAudio_num_upd; /* Number of calls to update function */
static int SDL_MintAudio_max_buf; /* Number of buffers to use */
static int SDL_MintAudio_numbuf; /* Buffer to play */

static void SDL_MintAudio_Callback(void);

/* MiNT thread variables */
SDL_bool SDL_MintAudio_mint_present;
SDL_bool SDL_MintAudio_quit_thread;
SDL_bool SDL_MintAudio_thread_finished;
long SDL_MintAudio_thread_pid;

/* Debug print info */
#define DEBUG_NAME "audio:mint: "
#if 0
#define DEBUG_PRINT(what) \
{ \
printf what; \
}
#else
#define DEBUG_PRINT(what)
#endif

/* Initialize DMA buffers */

int SDL_MintAudio_InitBuffers(SDL_AudioSpec *spec)
{
SDL_AudioDevice *this = SDL_MintAudio_device;

SDL_CalculateAudioSpec(spec);
MINTAUDIO_audiosize = spec->size * MAX_DMA_BUF;

/* Allocate memory for audio buffers in DMA-able RAM */
MINTAUDIO_audiobuf[0] = Atari_SysMalloc(2 * MINTAUDIO_audiosize, MX_STRAM);
if (MINTAUDIO_audiobuf[0]==NULL) {
SDL_SetError("SDL_MintAudio_OpenAudio: Not enough memory for audio buffer");
return (0);
}
MINTAUDIO_audiobuf[1] = MINTAUDIO_audiobuf[0] + MINTAUDIO_audiosize;
SDL_memset(MINTAUDIO_audiobuf[0], spec->silence, 2 * MINTAUDIO_audiosize);

DEBUG_PRINT((DEBUG_NAME "buffer 0 at 0x%p\n", MINTAUDIO_audiobuf[0]));
DEBUG_PRINT((DEBUG_NAME "buffer 1 at 0x%p\n", MINTAUDIO_audiobuf[1]));

SDL_MintAudio_numbuf = SDL_MintAudio_num_its = SDL_MintAudio_num_upd = 0;
SDL_MintAudio_max_buf = MAX_DMA_BUF;

return (1);
}

/* Destroy DMA buffers */

void SDL_MintAudio_FreeBuffers(void)
{
SDL_AudioDevice *this = SDL_MintAudio_device;

if (MINTAUDIO_audiobuf[0]) {
Mfree(MINTAUDIO_audiobuf[0]);
MINTAUDIO_audiobuf[0] = MINTAUDIO_audiobuf[1] = NULL;
}
}

/* Update buffers */

void SDL_AtariMint_UpdateAudio(void)
{
SDL_AudioDevice *this = SDL_MintAudio_device;

++SDL_MintAudio_num_upd;

/* No interrupt triggered? still playing current buffer */
if (SDL_MintAudio_num_its==0) {
return;
}

if (SDL_MintAudio_num_upd < (SDL_MintAudio_num_its<<2)) {
/* Too many interrupts per update, increase latency */
if (SDL_MintAudio_max_buf < MAX_DMA_BUF) {
SDL_MintAudio_max_buf <<= 1;
}
} else if (SDL_MintAudio_num_its < (SDL_MintAudio_num_upd<<2)) {
/* Too many updates per interrupt, decrease latency */
if (SDL_MintAudio_max_buf > 1) {
SDL_MintAudio_max_buf >>= 1;
}
}
MINTAUDIO_audiosize = this->spec.size * SDL_MintAudio_max_buf;

SDL_MintAudio_num_its = 0;
SDL_MintAudio_num_upd = 0;

SDL_MintAudio_numbuf ^= 1;

/* Fill new buffer */
SDL_MintAudio_Callback();

/* And swap to it */
(*MINTAUDIO_swapbuf)(MINTAUDIO_audiobuf[SDL_MintAudio_numbuf], MINTAUDIO_audiosize);
}

/* The callback function, called by each driver whenever needed */

void SDL_MintAudio_Callback(void)
static void SDL_MintAudio_Callback(void)
{
SDL_AudioDevice *this = SDL_MintAudio_device;
Uint8 *buffer;
SDL_AudioDevice *audio = SDL_MintAudio_device;
int i;

buffer = SDL_MintAudio_audiobuf[SDL_MintAudio_numbuf];
SDL_memset(buffer, audio->spec.silence, audio->spec.size);
buffer = MINTAUDIO_audiobuf[SDL_MintAudio_numbuf];
SDL_memset(buffer, this->spec.silence, this->spec.size * SDL_MintAudio_max_buf);

if (audio->paused)
if (this->paused)
return;

if (audio->convert.needed) {
int silence;
for (i=0; i<SDL_MintAudio_max_buf; i++) {
if (this->convert.needed) {
int silence;

if ( this->convert.src_format == AUDIO_U8 ) {
silence = 0x80;
} else {
silence = 0;
}
SDL_memset(this->convert.buf, silence, this->convert.len);
this->spec.callback(this->spec.userdata,
(Uint8 *)this->convert.buf,this->convert.len);
SDL_ConvertAudio(&this->convert);
SDL_memcpy(buffer, this->convert.buf, this->convert.len_cvt);

if ( audio->convert.src_format == AUDIO_U8 ) {
silence = 0x80;
buffer += this->convert.len_cvt;
} else {
silence = 0;
this->spec.callback(this->spec.userdata, buffer, this->spec.size);

buffer += this->spec.size;
}
SDL_memset(audio->convert.buf, silence, audio->convert.len);
audio->spec.callback(audio->spec.userdata,
(Uint8 *)audio->convert.buf,audio->convert.len);
SDL_ConvertAudio(&audio->convert);
SDL_memcpy(buffer, audio->convert.buf, audio->convert.len_cvt);
} else {
audio->spec.callback(audio->spec.userdata, buffer, audio->spec.size);
}
}

Expand Down Expand Up @@ -141,45 +241,26 @@ int SDL_MintAudio_SearchFrequency(_THIS, int desired_freq)
return MINTAUDIO_freqcount-1;
}

/* Check if FPU is present */
void SDL_MintAudio_CheckFpu(void)
{
long cookie_fpu;

SDL_MintAudio_hasfpu = 0;
if (Getcookie(C__FPU, &cookie_fpu) != C_FOUND) {
return;
}
switch ((cookie_fpu>>16)&0xfffe) {
case 2:
case 4:
case 6:
case 8:
case 16:
SDL_MintAudio_hasfpu = 1;
break;
}
}

/* The thread function, used under MiNT with xbios */
int SDL_MintAudio_Thread(long param)
{
SndBufPtr pointers;
SDL_bool buffers_filled[2] = {SDL_FALSE, SDL_FALSE};
SDL_AudioDevice *this = SDL_MintAudio_device;

SDL_MintAudio_thread_finished = SDL_FALSE;
while (!SDL_MintAudio_quit_thread) {
if (Buffptr(&pointers)!=0)
continue;

if (( (unsigned long)pointers.play>=(unsigned long)SDL_MintAudio_audiobuf[0])
&& ( (unsigned long)pointers.play<=(unsigned long)SDL_MintAudio_audiobuf[1]))
if (( (unsigned long)pointers.play>=(unsigned long)MINTAUDIO_audiobuf[0])
&& ( (unsigned long)pointers.play<=(unsigned long)MINTAUDIO_audiobuf[1]))
{
/* DMA is reading buffer #0, setup buffer #1 if not already done */
if (!buffers_filled[1]) {
SDL_MintAudio_numbuf = 1;
SDL_MintAudio_Callback();
Setbuffer(0, SDL_MintAudio_audiobuf[1], SDL_MintAudio_audiobuf[1] + SDL_MintAudio_audiosize);
Setbuffer(0, MINTAUDIO_audiobuf[1], MINTAUDIO_audiobuf[1] + MINTAUDIO_audiosize);
buffers_filled[1]=SDL_TRUE;
buffers_filled[0]=SDL_FALSE;
}
Expand All @@ -188,7 +269,7 @@ int SDL_MintAudio_Thread(long param)
if (!buffers_filled[0]) {
SDL_MintAudio_numbuf = 0;
SDL_MintAudio_Callback();
Setbuffer(0, SDL_MintAudio_audiobuf[0], SDL_MintAudio_audiobuf[0] + SDL_MintAudio_audiosize);
Setbuffer(0, MINTAUDIO_audiobuf[0], MINTAUDIO_audiobuf[0] + MINTAUDIO_audiosize);
buffers_filled[0]=SDL_TRUE;
buffers_filled[1]=SDL_FALSE;
}
Expand Down
39 changes: 23 additions & 16 deletions src/audio/mint/SDL_mintaudio.h
View file
Expand Up @@ -48,15 +48,23 @@ typedef struct {

struct SDL_PrivateAudioData {
mint_frequency_t frequencies[MINTAUDIO_maxfreqs];
int freq_count; /* Number of frequencies in the array */
int numfreq; /* Number of selected frequency */
int freq_count; /* Number of frequencies in the array */
int numfreq; /* Number of selected frequency */

Uint8 *audiobuf[2]; /* DMA buffers */
int audiosize; /* and their size, variable depending on latency */

void (*swapbuf)(Uint8 *nextbuf, int nextsize); /* Routine to swap DMA buffers */
};

/* Old variable names */

#define MINTAUDIO_frequencies (this->hidden->frequencies)
#define MINTAUDIO_freqcount (this->hidden->freq_count)
#define MINTAUDIO_numfreq (this->hidden->numfreq)
#define MINTAUDIO_freqcount (this->hidden->freq_count)
#define MINTAUDIO_numfreq (this->hidden->numfreq)
#define MINTAUDIO_swapbuf (this->hidden->swapbuf)
#define MINTAUDIO_audiobuf (this->hidden->audiobuf)
#define MINTAUDIO_audiosize (this->hidden->audiosize)

/* _MCH cookie (values>>16) */
enum {
Expand Down Expand Up @@ -85,13 +93,6 @@ enum {

/* Variables */
extern SDL_AudioDevice *SDL_MintAudio_device;
extern Uint8 *SDL_MintAudio_audiobuf[2]; /* Pointers to buffers */
extern unsigned long SDL_MintAudio_audiosize; /* Length of audio buffer=spec->size */
extern volatile unsigned short SDL_MintAudio_numbuf; /* Buffer to play */
extern volatile unsigned short SDL_MintAudio_mutex;
extern cookie_stfa_t *SDL_MintAudio_stfa;
extern volatile unsigned long SDL_MintAudio_clocktics;
extern unsigned short SDL_MintAudio_hasfpu; /* To preserve fpu registers if needed */

/* MiNT thread variables */
extern SDL_bool SDL_MintAudio_mint_present;
Expand All @@ -100,19 +101,25 @@ extern SDL_bool SDL_MintAudio_thread_finished;
extern long SDL_MintAudio_thread_pid;

/* Functions */
void SDL_MintAudio_Callback(void);
void SDL_AtariMint_UpdateAudio(void);

int SDL_MintAudio_InitBuffers(SDL_AudioSpec *spec);
void SDL_MintAudio_FreeBuffers(void);
void SDL_MintAudio_AddFrequency(_THIS, Uint32 frequency, Uint32 clock,
Uint32 prediv, int gpio_bits);
int SDL_MintAudio_SearchFrequency(_THIS, int desired_freq);
void SDL_MintAudio_CheckFpu(void);

/* MiNT thread functions */
int SDL_MintAudio_Thread(long param);
void SDL_MintAudio_WaitThread(void);

/* ASM interrupt functions */
void SDL_MintAudio_GsxbInterrupt(void);
void SDL_MintAudio_EmptyGsxbInterrupt(void);
/*--- SDL_mintaudio_it.S stuff ---*/

/* Variables */
extern volatile unsigned long SDL_MintAudio_clocktics;
extern volatile unsigned long SDL_MintAudio_num_its;

/* Functions */
void SDL_MintAudio_XbiosInterruptMeasureClock(void);
void SDL_MintAudio_XbiosInterrupt(void);
void SDL_MintAudio_Dma8Interrupt(void);
Expand Down

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