81 lines
2.5 KiB
C
81 lines
2.5 KiB
C
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#include "gb.h"
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#include "timing.h"
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#include "memory.h"
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void advance_cycles(GB_gameboy_t *gb, unsigned char cycles)
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{
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// Affected by speed boost
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if (gb->dma_cycles > cycles){
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gb->dma_cycles -= cycles;
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}
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else {
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gb->dma_cycles = 0;
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}
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if (gb->cgb_double_speed) {
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cycles >>=1;
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}
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// Not affected by speed boost
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gb->hdma_cycles += cycles;
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gb->display_cycles += cycles;
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gb->div_cycles += cycles;
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gb->tima_cycles += cycles;
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gb->apu_cycles += cycles;
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hdma_run(gb);
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timers_run(gb);
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apu_run(gb);
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}
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void timers_run(GB_gameboy_t *gb)
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{
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/* Standard Timers */
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static const unsigned long GB_TAC_RATIOS[] = {1024, 16, 64, 256};
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if (gb->div_cycles >= DIV_CYCLES) {
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gb->div_cycles -= DIV_CYCLES;
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gb->io_registers[GB_IO_DIV]++;
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}
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while (gb->tima_cycles >= GB_TAC_RATIOS[gb->io_registers[GB_IO_TAC] & 3]) {
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gb->tima_cycles -= GB_TAC_RATIOS[gb->io_registers[GB_IO_TAC] & 3];
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if (gb->io_registers[GB_IO_TAC] & 4) {
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gb->io_registers[GB_IO_TIMA]++;
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if (gb->io_registers[GB_IO_TIMA] == 0) {
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gb->io_registers[GB_IO_TIMA] = gb->io_registers[GB_IO_TMA];
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gb->io_registers[GB_IO_IF] |= 4;
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}
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}
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}
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/* RTC */
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if (gb->display_cycles >= LCDC_PERIOD) { /* Time is a syscall and therefore is slow, so we update the RTC
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only during vblanks. */
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if ((gb->rtc_high & 0x40) == 0) { /* is timer running? */
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time_t current_time = time(NULL);
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while (gb->last_rtc_second < current_time) {
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gb->last_rtc_second++;
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if (++gb->rtc_seconds == 60)
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{
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gb->rtc_seconds = 0;
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if (++gb->rtc_minutes == 60)
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{
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gb->rtc_minutes = 0;
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if (++gb->rtc_hours == 24)
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{
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gb->rtc_hours = 0;
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if (++gb->rtc_days == 0)
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{
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if (gb->rtc_high & 1) /* Bit 8 of days*/
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{
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gb->rtc_high |= 0x80; /* Overflow bit */
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}
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gb->rtc_high ^= 1;
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}
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}
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}
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}
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}
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}
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}
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}
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