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32x pwm, tiny optimization

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This commit is contained in:
kub 2020-04-13 22:22:33 +02:00
parent 74cc7aebf6
commit bb0488a6ba
1 changed files with 11 additions and 11 deletions
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22
pico/32x/pwm.c
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@ -9,7 +9,7 @@
static struct { static struct {
int cycles; int cycles;
int mult; unsigned mult;
int ptr; int ptr;
int irq_reload; int irq_reload;
int doing_fifo; int doing_fifo;
@ -58,11 +58,11 @@ static void do_pwm_irq(SH2 *sh2, unsigned int m68k_cycles)
static int convert_sample(unsigned int v) static int convert_sample(unsigned int v)
{ {
if (v == 0)
return 0;
if (v > pwm.cycles) if (v > pwm.cycles)
v = pwm.cycles; v = pwm.cycles;
return (v * 2 - pwm.cycles) / 2 * pwm.mult; if (v == 0)
return 0;
return v * pwm.mult - 0x10000/2;
} }
#define consume_fifo(sh2, m68k_cycles) { \ #define consume_fifo(sh2, m68k_cycles) { \
@ -89,19 +89,21 @@ static void consume_fifo_do(SH2 *sh2, unsigned int m68k_cycles,
// this is for recursion from dreq1 writes // this is for recursion from dreq1 writes
pwm.doing_fifo = 1; pwm.doing_fifo = 1;
for (; sh2_cycles_diff >= pwm.cycles; sh2_cycles_diff -= pwm.cycles) while (sh2_cycles_diff >= pwm.cycles)
{ {
sh2_cycles_diff -= pwm.cycles;
if (Pico32x.pwm_p[0] > 0) { if (Pico32x.pwm_p[0] > 0) {
mem->pwm_index[0] = (mem->pwm_index[0]+1) % 4; mem->pwm_index[0] = (mem->pwm_index[0]+1) % 4;
Pico32x.pwm_p[0]--; Pico32x.pwm_p[0]--;
pwm.current[0] = convert_sample(fifo_l[mem->pwm_index[0]]); pwm.current[0] = convert_sample(fifo_l[mem->pwm_index[0]]);
sum |= pwm.current[0]; sum |= (u16)pwm.current[0];
} }
if (Pico32x.pwm_p[1] > 0) { if (Pico32x.pwm_p[1] > 0) {
mem->pwm_index[1] = (mem->pwm_index[1]+1) % 4; mem->pwm_index[1] = (mem->pwm_index[1]+1) % 4;
Pico32x.pwm_p[1]--; Pico32x.pwm_p[1]--;
pwm.current[1] = convert_sample(fifo_r[mem->pwm_index[1]]); pwm.current[1] = convert_sample(fifo_r[mem->pwm_index[1]]);
sum |= pwm.current[1]; sum |= (u16)pwm.current[1];
} }
mem->pwm[pwm.ptr * 2 ] = pwm.current[0]; mem->pwm[pwm.ptr * 2 ] = pwm.current[0];
@ -234,9 +236,7 @@ void p32x_pwm_write16(unsigned int a, unsigned int d,
fifo = Pico32xMem->pwm_fifo[1]; fifo = Pico32xMem->pwm_fifo[1];
idx = Pico32xMem->pwm_index[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) if (Pico32x.pwm_p[1] == 2 && 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, // buffer full. If there was no buffer underrun after last fill,
// try increasing reload rate to reduce IRQs // try increasing reload rate to reduce IRQs
if (pwm.irq_reload < 3 && pwm.irq_state == PWM_IRQ_HIGH) if (pwm.irq_reload < 3 && pwm.irq_state == PWM_IRQ_HIGH)
@ -250,7 +250,7 @@ void p32x_pwm_write16(unsigned int a, unsigned int d,
pwm.irq_reload = pwm.irq_timer; pwm.irq_reload = pwm.irq_timer;
pwm.irq_state = PWM_IRQ_LOCKED; pwm.irq_state = PWM_IRQ_LOCKED;
idx = (idx+1) % 4; idx = (idx+1) % 4;
Pico32xMem->pwm_index[0] = idx; Pico32xMem->pwm_index[1] = idx;
} }
fifo[(idx+Pico32x.pwm_p[1]) % 4] = (d - 1) & 0x0fff; fifo[(idx+Pico32x.pwm_p[1]) % 4] = (d - 1) & 0x0fff;
if (a != 8) break; // fallthrough if MONO if (a != 8) break; // fallthrough if MONO