87 lines
1.7 KiB
Odin
87 lines
1.7 KiB
Odin
package machine
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// System struct, init, constants, fontset
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System :: struct {
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// 4kb ram
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memory: [4096]u8,
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// 16 general purpose 8bit registers 0 -> F
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v: [16]u8,
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// Call stack, up to 16, 2 byte addresses.
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stack: [16]u16,
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// Stack pointer
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sp: u8,
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// index register
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i: u16,
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// PC program counter
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pc: u16,
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// 64x32-pixel monochrome display
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display: [32][64]u8,
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// Keypad
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keypad: [16]bool,
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// -1 = no key pressed, 0-15 = key index
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current_key: i16,
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// Timers
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delay_timer: u8,
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sound_timer: u8,
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}
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FONT_SET := [80]u8 {
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0xF0, 0x90, 0x90, 0x90, 0xF0, // 0
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0x20, 0x60, 0x20, 0x20, 0x70, // 1
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0xF0, 0x10, 0xF0, 0x80, 0xF0, // 2
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0xF0, 0x10, 0xF0, 0x10, 0xF0, // 3
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0x90, 0x90, 0xF0, 0x10, 0x10, // 4
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0xF0, 0x80, 0xF0, 0x10, 0xF0, // 5
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0xF0, 0x80, 0xF0, 0x90, 0xF0, // 6
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0xF0, 0x10, 0x20, 0x40, 0x40, // 7
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0xF0, 0x90, 0xF0, 0x90, 0xF0, // 8
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0xF0, 0x90, 0xF0, 0x10, 0xF0, // 9
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0xF0, 0x90, 0xF0, 0x90, 0x90, // A
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0xE0, 0x90, 0xE0, 0x90, 0xE0, // B
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0xF0, 0x80, 0x80, 0x80, 0xF0, // C
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0xE0, 0x90, 0x90, 0x90, 0xE0, // D
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0xF0, 0x80, 0xF0, 0x80, 0xF0, // E
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0xF0, 0x80, 0xF0, 0x80, 0x80 // F
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}
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init :: proc() -> System {
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// log.info("Booting chip 8 cpu")
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// Structs are zero initialized so timers, sp etc are good.
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s := System { pc = 0x200 }
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// load fonts into the memory
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for v, i in FONT_SET {
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s.memory[i] = v
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}
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return s
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}
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run_machine :: proc(s: ^System, cycles: int) {
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// CPU cycles
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for _ in 0..<cycles {
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handle_input(s)
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cycle(s)
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}
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}
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reset_machine :: proc(s: ^System) {
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s.memory = {}
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s.v = {}
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s.stack = {}
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s.sp = 0
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s.i = 0
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s.pc = 0x200
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s.display = {}
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s.keypad = {}
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s.current_key = -1
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s.delay_timer = 0
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s.sound_timer = 0
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for v, i in FONT_SET {
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s.memory[i] = v
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}
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}
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