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"Bufferless" SB mixing
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@polpo
polpo committed Jan 27, 2024
1 parent 3f8f159 commit 3a783e3
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Showing 4 changed files with 41 additions and 66 deletions.
6 changes: 5 additions & 1 deletion sw/adlibplay.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,7 @@ extern "C" void OPL_Pico_Mix_callback(audio_buffer_t *);
extern void sbdsp_process(void);
extern void sbdsp_mix(audio_buffer_t *buffer);
extern uint16_t sbdsp_fifo_level();
extern int16_t sbdsp_sample();
#endif


Expand All @@ -104,7 +105,10 @@ void play_adlib() {

for (;;) {
struct audio_buffer *buffer = take_audio_buffer(ap, true);
sbdsp_mix(buffer);
// sbdsp_mix(buffer);
int16_t *samples = (int16_t *) buffer->buffer->bytes;
samples[0] = samples[1] = sbdsp_sample();
buffer->sample_count=1;
// putchar((unsigned char)buffer->buffer->bytes[1]);
give_audio_buffer(ap, buffer);
#ifdef USB_JOYSTICK
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4 changes: 4 additions & 0 deletions sw/opl/opl_pico.c
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Expand Up @@ -184,6 +184,10 @@ extern void TrackTimerCallback(void *track);
extern uint8_t restart_song_state;
#endif

void OPL_Pico_simple(int16_t *buffer, uint32_t nsamples) {
OPL_calc_buffer(emu8950_opl, buffer, nsamples);
}

void OPL_Pico_Mix_callback(audio_buffer_t *audio_buffer)
{
unsigned int filled, buffer_samples;
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4 changes: 2 additions & 2 deletions sw/pico_pic.c
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Original file line number Diff line number Diff line change
Expand Up @@ -30,8 +30,8 @@ int64_t PIC_HandleEvent(alarm_id_t id, void *user_data) {
return ret;
}
// A negative return value re-sets the alarm from the time when it initially triggered
/* return -(int64_t)ret; */
return (int64_t)ret;
return -(int64_t)ret;
/* return (int64_t)ret; */
#else
if (ret) {
event->deadline = time_us_32() + ret;
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93 changes: 30 additions & 63 deletions sw/sbplay.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ Author : Kevin Moonlight <[email protected]>
#include "isa_dma.h"

extern "C" void OPL_Pico_Mix_callback(audio_buffer_t *);
extern "C" void OPL_Pico_simple(int16_t *buffer, uint32_t nsamples);


irq_handler_t SBDSP_DMA_isr_pt;
Expand Down Expand Up @@ -167,95 +168,57 @@ void sbdsp_dma_enable() {
}
}

static bool done; // TODO I don't like this flag

uint32_t DSP_DMA_Event(Bitu val) {
if(sbdsp_fifo_half()) {
sbdsp.dma_interval_trim = 5;
}
else {
sbdsp.dma_interval_trim=-5;
}

DMA_Start_Write(&dma_config);
return 0;
}

void sbdsp_dma_isr(void) {
const uint32_t dma_data = DMA_Complete_Write(&dma_config);
uint16_t current_interval;
sbdsp_fifo_rx(dma_data & 0xFF);
uint32_t current_interval;
sbdsp.dma_sample_count_rx++;

if(sbdsp.dma_pause_duration) {
current_interval = sbdsp.dma_interval * sbdsp.dma_pause_duration;
sbdsp.dma_pause_duration=0;
}
else {
current_interval = sbdsp.dma_interval + sbdsp.dma_interval_trim;
current_interval = sbdsp.dma_interval;
}


if(sbdsp.dma_sample_count_rx <= sbdsp.dma_sample_count) {
PIC_AddEvent(DSP_DMA_Event,current_interval,1);
return current_interval;
}
else {
done = true;
if(sbdsp.autoinit) {
sbdsp.dma_sample_count_rx=0;
PIC_AddEvent(DSP_DMA_Event,current_interval,1);
return current_interval;
}
else {
sbdsp_dma_disable();
}
PIC_ActivateIRQ();
}
}
return 0;
}

static volatile uint8_t cur_sample; // TODO move to sbdsp struct

void sbdsp_mix(audio_buffer_t *buffer) {
uint16_t i,x,y,req_bytes,rx_bytes;
int16_t *samples, *opl_samples;
uint32_t offset;
uint32_t step;

uint64_t starting_offset;

char buf[1024];
buffer->sample_count=0;
samples = (int16_t *) buffer->buffer->bytes;
opl_samples = (int16_t *) opl_buffer->buffer->bytes;
if(sbdsp.dma_enabled) {
while(!sbdsp_fifo_level()) {//TODO: This is not ideal to block here.
}
if(1==1) {//sbdsp_fifo_level() >= 16 ) {//TODO: this will be problem at the end.
x = sbdsp_fifo_tx(buf,sbdsp.dma_transfer_size); //4
starting_offset = sbdsp.sample_offset >> 16;
for(i=0;i<(x*sbdsp.sample_factor);i++) {
y=(sbdsp.sample_offset >> 16) - starting_offset;
if(y >= x) break;
samples[(i<<1)+0] = buf[y]-0x80 << 4;
samples[(i<<1)+1] = buf[y]-0x80 << 4;
sbdsp.sample_offset += sbdsp.sample_step;
}
buffer->sample_count = i;
buffer->max_sample_count=i;
}
else {
buffer->sample_count=0;
}
}
void sbdsp_dma_isr(void) {
if (done) {
done = false;
PIC_ActivateIRQ();
}
const uint32_t dma_data = DMA_Complete_Write(&dma_config);
uint16_t current_interval;
cur_sample = dma_data & 0xFF;
}

if(!buffer->sample_count) {
buffer->sample_count=1;
for(x=0;x<buffer->sample_count*2;x++) samples[x]=0;
int16_t sbdsp_sample() {
int16_t snd16;
OPL_Pico_simple(&snd16, 1);
if (sbdsp.dma_enabled) {
snd16 += (int16_t)(cur_sample)-0x80 << 4;
}

opl_buffer->max_sample_count = buffer->sample_count;
OPL_Pico_Mix_callback(opl_buffer);
for(x=0;x<buffer->sample_count*2;x++) {
samples[x] += opl_samples[x];
}


return;
return snd16;
}

void sbdsp_init() {
Expand Down Expand Up @@ -328,8 +291,12 @@ void sbdsp_process(void) {
if(sbdsp.current_command_index==1) {
//printf("(0x40) DSP_SET_TIME_CONSTANT\n\r");
sbdsp.time_constant = sbdsp.inbox;
/*
sbdsp.sample_rate = 1000000ul / (256 - sbdsp.time_constant);
sbdsp.dma_interval = 1000000ul / sbdsp.sample_rate; // redundant.
*/
sbdsp.dma_interval = 256 - sbdsp.time_constant;
sbdsp.sample_rate = 1000000ul / sbdsp.dma_interval;
sbdsp.sample_step = sbdsp.sample_rate * 65535ul / OUTPUT_SAMPLERATE;
sbdsp.sample_factor = (OUTPUT_SAMPLERATE / sbdsp.sample_rate)+5; //Estimate

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