40 lines
610 B
C
40 lines
610 B
C
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#include <dma.h>
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#include <ppu.h>
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#include <bus.h>
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typedef struct {
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bool active;
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u8 byte;
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u8 value;
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u8 start_delay;
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} dma_context;
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static dma_context ctx;
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void dma_start(u8 start) {
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ctx.active = true;
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ctx.byte = 0;
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ctx.start_delay = 2;
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ctx.value = start;
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}
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void dma_tick() {
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if (!ctx.active) {
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return;
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}
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if (ctx.start_delay) {
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ctx.start_delay--;
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return;
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}
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ppu_oam_write(ctx.byte, bus_read((ctx.value * 0x100) + ctx.byte));
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ctx.byte++;
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ctx.active = ctx.byte < 0xA0;
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}
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bool dma_transferring() {
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return ctx.active;
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}
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