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32x, configurable pwm irq optimization to reduce pwm irq load

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This commit is contained in:
kub 2019-10-11 00:02:23 +02:00
parent 86c16afd45
commit 20d2358ab1
4 changed files with 32 additions and 6 deletions
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35
pico/32x/pwm.c
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@ -14,13 +14,18 @@ static struct {
int irq_reload;
int doing_fifo;
int silent;
int irq_timer;
int irq_state;
short current[2];
} pwm;
enum { PWM_IRQ_LOCKED, PWM_IRQ_STOPPED, PWM_IRQ_LOW, PWM_IRQ_HIGH };
void p32x_pwm_ctl_changed(void)
{
int control = Pico32x.regs[0x30 / 2];
int cycles = Pico32x.regs[0x32 / 2];
int pwm_irq_opt = PicoIn.opt & POPT_PWM_IRQ_OPT;
cycles = (cycles - 1) & 0x0fff;
pwm.cycles = cycles;
@ -31,8 +36,10 @@ void p32x_pwm_ctl_changed(void)
if ((control & 0x0f) != 0)
pwm.mult = 0x10000 / cycles;
pwm.irq_reload = (control & 0x0f00) >> 8;
pwm.irq_reload = ((pwm.irq_reload - 1) & 0x0f) + 1;
pwm.irq_timer = (control & 0x0f00) >> 8;
pwm.irq_timer = ((pwm.irq_timer - 1) & 0x0f) + 1;
pwm.irq_reload = pwm.irq_timer;
pwm.irq_state = pwm_irq_opt ? PWM_IRQ_STOPPED: PWM_IRQ_LOCKED;
if (Pico32x.pwm_irq_cnt == 0)
Pico32x.pwm_irq_cnt = pwm.irq_reload;
@ -104,6 +111,11 @@ static void consume_fifo_do(SH2 *sh2, unsigned int m68k_cycles,
if (--Pico32x.pwm_irq_cnt == 0) {
Pico32x.pwm_irq_cnt = pwm.irq_reload;
do_pwm_irq(sh2, m68k_cycles);
} else if (Pico32x.pwm_p[1] == 0 && pwm.irq_state >= PWM_IRQ_LOW) {
// buffer underrun. Reduce reload rate if above programmed setting.
if (pwm.irq_reload > pwm.irq_timer)
pwm.irq_reload--;
pwm.irq_state = PWM_IRQ_LOW;
}
}
Pico32x.pwm_cycle_p = m68k_cycles * 3 - sh2_cycles_diff;
@ -221,10 +233,22 @@ void p32x_pwm_write16(unsigned int a, unsigned int d,
case 6/2: // R ch
fifo = Pico32xMem->pwm_fifo[1];
idx = Pico32xMem->pwm_index[1];
if (Pico32x.pwm_p[1] < 3)
if (Pico32x.pwm_p[1] < 3) {
if (pwm.irq_state == PWM_IRQ_STOPPED)
pwm.irq_state = PWM_IRQ_LOW;
if (Pico32x.pwm_p[1] == 2 && pwm.irq_state >= PWM_IRQ_LOW) {
// buffer full. If there was no buffer underrun after last fill,
// try increasing reload rate to reduce IRQs
if (pwm.irq_reload < 3 && pwm.irq_state == PWM_IRQ_HIGH)
pwm.irq_reload ++;
pwm.irq_state = PWM_IRQ_HIGH;
}
Pico32x.pwm_p[1]++;
else {
// fifo[(idx+1) % 4] = fifo[idx];
} else {
// buffer overflow. Some roms always fill the complete buffer even if
// reload rate is set below max. Lock reload rate to programmed setting.
pwm.irq_reload = pwm.irq_timer;
pwm.irq_state = PWM_IRQ_LOCKED;
idx = (idx+1) % 4;
Pico32xMem->pwm_index[0] = idx;
}
@ -236,7 +260,6 @@ void p32x_pwm_write16(unsigned int a, unsigned int d,
if (Pico32x.pwm_p[0] < 3)
Pico32x.pwm_p[0]++;
else {
// fifo[(idx+1) % 4] = fifo[idx];
idx = (idx+1) % 4;
Pico32xMem->pwm_index[0] = idx;
}