56 lines
1.4 KiB
C
56 lines
1.4 KiB
C
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#include <stdio.h>
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#include <string.h>
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#include "apu.h"
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struct apu apu = {0};
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void
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apu_init(void)
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{
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memset(&apu, 0, sizeof(apu));
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}
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uint8_t
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apu_read(uint16_t addr)
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{
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switch (addr) {
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/* pulse1 */
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case 0x4000:
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return (apu.pulse1.duty << 6) | (apu.pulse1.envelope << 5)
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| (apu.pulse1.const_vol << 4) | apu.pulse1.envelope_vol;
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case 0x4001:
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return (apu.pulse1.sweep_enable << 7) | (apu.pulse1.sweep_period << 4)
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| (apu.pulse1.sweep_negative << 3) | apu.pulse1.sweep_shift_count;
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case 0x4002:
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return apu.pulse1.timer_low;
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case 0x4003:
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return (apu.pulse1.length_counter_load << 3) | apu.pulse1.timer_high;
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/* pulse2 */
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case 0x4004:
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return (apu.pulse2.duty << 6) | (apu.pulse2.envelope << 5)
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| (apu.pulse2.const_vol << 4) | apu.pulse2.envelope_vol;
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case 0x4005:
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return (apu.pulse1.sweep_enable << 7) | (apu.pulse1.sweep_period << 4)
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| (apu.pulse1.sweep_negative << 3) | apu.pulse1.sweep_shift_count;
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case 0x4006:
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return apu.pulse1.timer_low;
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case 0x4007:
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return (apu.pulse1.length_counter_load << 3) | apu.pulse1.timer_high;
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/* status */
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case 0x4015:
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return (apu.status.dmc_int << 7) | (apu.status.frame_int << 6)
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| (apu.status.dmc_active << 4) | (apu.status.lc_noise << 3)
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| (apu.status.lc_triangle << 2) | (apu.status.lc_pulse2 << 1)
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| apu.status.lc_pulse1;
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default:
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fprintf(stderr, "Invalid APU read at $%04X!\n", addr);
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return 0;
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};
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}
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void
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apu_write(uint16_t addr, uint8_t byte)
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{
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}
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