106 lines
2.0 KiB
C
106 lines
2.0 KiB
C
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#ifndef APU_H
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#define APU_H
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#include <stdint.h>
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struct pulse {
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/* $4000/$4004 */
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uint8_t duty : 2;
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uint8_t envelope : 1;
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uint8_t const_vol : 1;
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uint8_t envelope_vol : 4;
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/* $4001/$4005 */
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uint8_t sweep_enable : 1;
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uint8_t sweep_period : 3;
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uint8_t sweep_negative : 1;
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uint8_t sweep_shift_count : 3;
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/* $4002/$4006 */
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uint8_t timer_low;
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/* $4003/$4007 */
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uint8_t length_counter_load : 5;
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uint8_t timer_high : 3;
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};
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struct triangle {
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/* $4008 */
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uint8_t counter_disable : 1;
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uint8_t counter_reload : 7;
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/* $400A */
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uint8_t timer_low;
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/* $400B */
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uint8_t counter_load : 5;
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uint8_t timer_high : 3;
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};
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struct noise {
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/* $400C */
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uint8_t padding1 : 2;
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uint8_t loop_envelope : 1;
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uint8_t constant_volume : 1;
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uint8_t envelope_volume : 4;
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/* $400E */
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uint8_t loop_noise : 1;
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uint8_t padding2 : 3;
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uint8_t noise_period : 4;
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/* $400F */
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uint8_t length_counter_load : 5;
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uint8_t padding3 : 3;
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};
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struct dmc {
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/* $4010 */
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uint8_t irq_enable : 1;
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uint8_t loop : 1;
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uint8_t padding1 : 2;
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uint8_t frequency : 4;
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/* $4011 */
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uint8_t padding2 : 1;
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uint8_t load_counter : 7;
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/* $4012 */
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uint8_t sample_addr;
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/* $4013 */
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uint8_t sample_length;
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};
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struct apu {
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/* $4000-$4013 (write) */
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struct pulse pulse1;
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struct pulse pulse2;
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struct triangle triangle;
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struct noise noise;
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struct dmc dmc;
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/* $4015 (write) */
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struct control {
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uint8_t padding : 3;
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uint8_t dmc_enable : 1;
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uint8_t noise_enable : 1;
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uint8_t triangle_enable : 1;
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uint8_t pulse2_enable : 1;
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uint8_t pulse1_enable : 1;
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} control;
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/* $4015 (read) */
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struct status {
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uint8_t dmc_int : 1;
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uint8_t frame_int : 1;
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uint8_t padding : 1;
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uint8_t dmc_active : 1;
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uint8_t lc_noise : 1;
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uint8_t lc_triangle : 1;
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uint8_t lc_pulse2 : 1;
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uint8_t lc_pulse1 : 1;
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} status;
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/* $4017 (write) */
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struct frame_counter {
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uint8_t mode : 1;
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uint8_t irq_inhibit : 1;
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uint8_t padding : 6;
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} frame_counter;
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};
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extern struct apu apu;
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void apu_tick(void);
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uint8_t apu_read(uint16_t addr);
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void apu_write(uint16_t addr, uint8_t byte);
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#endif /* APU_H */
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