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core, improve pico save/load (ADPCM state, page, etc)
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@irixxxx
irixxxx committed Jan 23, 2024
1 parent 8ff5eee commit 0e1726c
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Showing 5 changed files with 136 additions and 78 deletions.
7 changes: 2 additions & 5 deletions pico/pico.h
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Original file line number Diff line number Diff line change
Expand Up @@ -150,17 +150,14 @@ void PicoGetInternal(pint_t which, pint_ret_t *ret);
struct PicoEState;

// pico.c
#define XPCM_BUFFER_SIZE (320+160)
#define XPCM_BUFFER_SIZE 64
typedef struct
{
int pen_pos[2];
int page;
// internal
int fifo_bytes; // bytes in FIFO
int fifo_bytes_prev;
int fifo_line_bytes; // float part, << 16
int line_counter;
unsigned short r1, r12;
unsigned int reserved[3];
unsigned char xpcm_buffer[XPCM_BUFFER_SIZE+4];
unsigned char *xpcm_ptr;
} picohw_state;
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1 change: 1 addition & 0 deletions pico/pico/pico.c
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@ picohw_state PicoPicohw;
PICO_INTERNAL void PicoReratePico(void)
{
PicoPicoPCMRerate();
PicoPicohw.xpcm_ptr = PicoPicohw.xpcm_buffer + PicoPicohw.fifo_bytes;
}

static void PicoLinePico(void)
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155 changes: 98 additions & 57 deletions pico/pico/xpcm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -42,14 +42,23 @@ static const int step_deltas[16][16] =

static const int state_deltas[16] = { -1, -1, 0, 0, 1, 2, 2, 3, -1, -1, 0, 0, 1, 2, 2, 3 };

static int sample = 0, state = 0;
static s32 stepsamples = (44100LL<<16)/ADPCM_CLOCK;
static s32 samplepos;
static int samplegain;
s32 stepsamples = (44100LL<<16)/ADPCM_CLOCK;

static int startpin, irqenable;
static enum { RESET, START, HDR, COUNT } portstate = RESET;
static int rate, silence, nibbles, highlow, cache;
static struct xpcm_state {
s32 samplepos; // leftover duration for current sample wrt sndrate, Q16
int sample; // current sample
short state; // ADPCM engine state
short samplegain; // programmable gain

char startpin; // value on the !START pin
char irqenable; // IRQ enabled?

char portstate; // data stream state
short silence; // silence blocks still to be played
short rate, nibbles; // ADPCM nibbles still to be played
unsigned char highlow, cache; // nibble selector and cache
} xpcm;
enum { RESET, START, HDR, COUNT }; // portstate


// SEGA Pico specific filtering
Expand All @@ -58,8 +67,8 @@ static int rate, silence, nibbles, highlow, cache;
#define FP(f) (int)((f)*(1<<QB)) // convert to fixpoint

static struct iir2 { // 2nd order IIR
s32 a[2], gain; // coefficients
s32 y[3], x[3]; // filter history
s32 a[2], gain; // coefficients
s32 x[3], y[3]; // filter history
} filters[4];
static struct iir2 *filter;

Expand All @@ -85,6 +94,7 @@ static int PicoPicoFilterApply(struct iir2 *iir, int sample)
if (!iir)
return sample;

// NB Butterworth specific!
iir->x[0] = iir->x[1]; iir->x[1] = iir->x[2];
iir->x[2] = sample * iir->gain; // Qb
iir->y[0] = iir->y[1]; iir->y[1] = iir->y[2];
Expand All @@ -99,21 +109,21 @@ static int PicoPicoFilterApply(struct iir2 *iir, int sample)
PICO_INTERNAL void PicoPicoPCMResetN(int pin)
{
if (!pin) {
portstate = RESET;
sample = samplepos = state = 0;
portstate = nibbles = silence = 0;
} else if (portstate == RESET)
portstate = START;
xpcm.portstate = RESET;
xpcm.sample = xpcm.samplepos = xpcm.state = 0;
xpcm.nibbles = xpcm.silence = 0;
} else if (xpcm.portstate == RESET)
xpcm.portstate = START;
}

PICO_INTERNAL void PicoPicoPCMStartN(int pin)
{
startpin = pin;
xpcm.startpin = pin;
}

PICO_INTERNAL int PicoPicoPCMBusyN(void)
{
return (portstate <= START);
return (xpcm.portstate <= START);
}


Expand All @@ -125,14 +135,14 @@ PICO_INTERNAL void PicoPicoPCMRerate(void)
stepsamples = ((u64)PicoIn.sndRate<<16)/ADPCM_CLOCK;

// compute filter coefficients, cutoff at half the ADPCM sample rate
PicoPicoFilterCoeff(&filters[1], 5000/2, PicoIn.sndRate); // 5-6 KHz
PicoPicoFilterCoeff(&filters[2], 8000/2, PicoIn.sndRate); // 8-12 KHz
PicoPicoFilterCoeff(&filters[3], 14000/2, PicoIn.sndRate); // 14-16 KHz
PicoPicoFilterCoeff(&filters[1], 6000/2, PicoIn.sndRate); // 5-6 KHz
PicoPicoFilterCoeff(&filters[2], 9000/2, PicoIn.sndRate); // 8-12 KHz
PicoPicoFilterCoeff(&filters[3], 15000/2, PicoIn.sndRate); // 14-16 KHz
}

PICO_INTERNAL void PicoPicoPCMGain(int gain)
{
samplegain = gain*4;
xpcm.samplegain = gain*4;
}

PICO_INTERNAL void PicoPicoPCMFilter(int index)
Expand All @@ -144,32 +154,35 @@ PICO_INTERNAL void PicoPicoPCMFilter(int index)

PICO_INTERNAL void PicoPicoPCMIrqEn(int enable)
{
irqenable = (enable ? 3 : 0);
xpcm.irqenable = (enable ? 3 : 0);
}

// TODO need an interupt pending mask?
PICO_INTERNAL int PicoPicoIrqAck(int level)
{
return (PicoPicohw.fifo_bytes < FIFO_IRQ_THRESHOLD && level != irqenable ? irqenable : 0);
return (PicoPicohw.fifo_bytes < FIFO_IRQ_THRESHOLD && level != xpcm.irqenable
? xpcm.irqenable : 0);
}


// adpcm operation

#define apply_filter(v) PicoPicoFilterApply(filter, v)

// compute next ADPCM sample
#define do_sample(nibble) \
{ \
sample += step_deltas[state][nibble]; \
state += state_deltas[nibble]; \
state = (state < 0 ? 0 : state > 15 ? 15 : state); \
xpcm.sample += step_deltas[xpcm.state][nibble]; \
xpcm.state += state_deltas[nibble]; \
xpcm.state = (xpcm.state < 0 ? 0 : xpcm.state > 15 ? 15 : xpcm.state); \
}

// writes samples with sndRate, nearest neighbour resampling, filtering
#define write_sample(buffer, length, stereo) \
{ \
while (samplepos > 0 && length > 0) { \
int val = Limit(samplegain*sample, 16383, -16384); \
samplepos -= 1<<16; \
while (xpcm.samplepos > 0 && length > 0) { \
int val = Limit(xpcm.samplegain*xpcm.sample, 16383, -16384); \
xpcm.samplepos -= 1<<16; \
length --; \
if (buffer) { \
int out = apply_filter(val); \
Expand All @@ -191,56 +204,56 @@ PICO_INTERNAL void PicoPicoPCMUpdate(short *buffer, int length, int stereo)
// loop over FIFO data, generating ADPCM samples
while (length > 0 && src < lim)
{
if (silence > 0) {
silence --;
sample = 0;
samplepos += stepsamples*256;
if (xpcm.silence > 0) {
xpcm.silence --;
xpcm.sample = 0;
xpcm.samplepos += stepsamples*256;

} else if (nibbles > 0) {
nibbles --;
} else if (xpcm.nibbles > 0) {
xpcm.nibbles --;

if (highlow)
cache = *src++;
if (xpcm.highlow)
xpcm.cache = *src++;
else
cache <<= 4;
highlow = !highlow;
xpcm.cache <<= 4;
xpcm.highlow = !xpcm.highlow;

do_sample((cache & 0xf0) >> 4);
samplepos += stepsamples*rate;
do_sample((xpcm.cache & 0xf0) >> 4);
xpcm.samplepos += stepsamples*xpcm.rate;

} else switch (portstate) {
} else switch (xpcm.portstate) {
case RESET:
sample = 0;
samplepos += length<<16;
xpcm.sample = 0;
xpcm.samplepos += length<<16;
break;
case START:
if (startpin) {
if (xpcm.startpin) {
if (*src)
portstate ++;
xpcm.portstate ++;
else // kill 0x00 bytes at stream start
src ++;
} else {
sample = 0;
samplepos += length<<16;
xpcm.sample = 0;
xpcm.samplepos += length<<16;
}
break;
case HDR:
srcval = *src++;
nibbles = silence = rate = 0;
highlow = 1;
xpcm.nibbles = xpcm.silence = xpcm.rate = 0;
xpcm.highlow = 1;
if (srcval == 0) { // terminator
// HACK, kill leftover odd byte to avoid restart (Minna de Odorou)
if (lim-src == 1) src++;
portstate = START;
xpcm.portstate = START;
} else switch (srcval >> 6) {
case 0: silence = (srcval & 0x3f) + 1; break;
case 1: rate = (srcval & 0x3f) + 1; nibbles = 256; break;
case 2: rate = (srcval & 0x3f) + 1; portstate = COUNT; break;
case 0: xpcm.silence = (srcval & 0x3f) + 1; break;
case 1: xpcm.rate = (srcval & 0x3f) + 1; xpcm.nibbles = 256; break;
case 2: xpcm.rate = (srcval & 0x3f) + 1; xpcm.portstate = COUNT; break;
case 3: break;
}
break;
case COUNT:
nibbles = *src++ + 1; portstate = HDR;
xpcm.nibbles = *src++ + 1; xpcm.portstate = HDR;
break;
}

Expand All @@ -255,14 +268,14 @@ PICO_INTERNAL void PicoPicoPCMUpdate(short *buffer, int length, int stereo)
elprintf(EL_PICOHW, "xpcm update: over %i", di);

if (!irq && di < FIFO_IRQ_THRESHOLD)
irq = irqenable;
irq = xpcm.irqenable;
PicoPicohw.fifo_bytes = di;
} else if (src == lim && src != PicoPicohw.xpcm_buffer) {
PicoPicohw.xpcm_ptr = PicoPicohw.xpcm_buffer;
elprintf(EL_PICOHW, "xpcm update: under %i", length);

if (!irq)
irq = irqenable;
irq = xpcm.irqenable;
PicoPicohw.fifo_bytes = 0;
}

Expand All @@ -275,11 +288,39 @@ PICO_INTERNAL void PicoPicoPCMUpdate(short *buffer, int length, int stereo)

if (buffer && length) {
// for underflow, use last sample to avoid clicks
int val = Limit(samplegain*sample, 16383, -16384);
int val = Limit(xpcm.samplegain*xpcm.sample, 16383, -16384);
while (length--) {
int out = apply_filter(val);
*buffer++ += out;
if (stereo) *buffer++ += out;
}
}
}

PICO_INTERNAL int PicoPicoPCMSave(void *buffer, int length)
{
u8 *bp = buffer;

if (length < sizeof(xpcm) + sizeof(filters)) {
elprintf(EL_ANOMALY, "save buffer too small?");
return 0;
}

memcpy(bp, &xpcm, sizeof(xpcm));
bp += sizeof(xpcm);
memcpy(bp, filters, sizeof(filters));
bp += sizeof(filters);
return (bp - (u8*)buffer);
}

PICO_INTERNAL void PicoPicoPCMLoad(void *buffer, int length)
{
u8 *bp = buffer;

if (length >= sizeof(xpcm))
memcpy(&xpcm, bp, sizeof(xpcm));
bp += sizeof(xpcm);
if (length >= sizeof(xpcm) + sizeof(filters))
memcpy(filters, bp, sizeof(filters));
bp += sizeof(filters);
}
2 changes: 2 additions & 0 deletions pico/pico_int.h
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Original file line number Diff line number Diff line change
Expand Up @@ -853,6 +853,8 @@ PICO_INTERNAL void PicoPicoPCMGain(int gain);
PICO_INTERNAL void PicoPicoPCMFilter(int index);
PICO_INTERNAL void PicoPicoPCMIrqEn(int enable);
PICO_INTERNAL void PicoPicoPCMRerate(void);
PICO_INTERNAL int PicoPicoPCMSave(void *buffer, int length);
PICO_INTERNAL void PicoPicoPCMLoad(void *buffer, int length);

// sek.c
PICO_INTERNAL void SekInit(void);
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