Initial commit, with some added boiler plate.

2026-05-15 11:14:28 +02:00
parent 6ec91bee2e
commit 4fec0b5d94
6 changed files with 157 additions and 0 deletions
@@ -0,0 +1,84 @@
+package machine
+
+import "core:os"
+import "core:log"
+
+System :: struct {
+    // 4kb ram
+    memory: [4096]u8,
+    // 16 general purpose 8bit registers 0 -> F
+    v: [16]u8,
+    // Call stack, up to 16, 2 byte addresses.
+    stack: [16]u16,
+    // Stack pointer
+    sp: u8,
+    // index register
+    i: u16,
+    // PC program counter
+    pc: u16,
+    // 64x32-pixel monochrome display
+    display: [64][32]u8,
+    keypad: [16]bool,
+    delay_timer: u8,
+    sound_timer: u8,
+}
+
+FONT_SET := [80]u8 {
+    0xF0, 0x90, 0x90, 0x90, 0xF0,		// 0
+    0x20, 0x60, 0x20, 0x20, 0x70,		// 1
+    0xF0, 0x10, 0xF0, 0x80, 0xF0,		// 2
+    0xF0, 0x10, 0xF0, 0x10, 0xF0,		// 3
+    0x90, 0x90, 0xF0, 0x10, 0x10,		// 4
+    0xF0, 0x80, 0xF0, 0x10, 0xF0,		// 5
+    0xF0, 0x80, 0xF0, 0x90, 0xF0,		// 6
+    0xF0, 0x10, 0x20, 0x40, 0x40,		// 7
+    0xF0, 0x90, 0xF0, 0x90, 0xF0,		// 8
+    0xF0, 0x90, 0xF0, 0x10, 0xF0,		// 9
+    0xF0, 0x90, 0xF0, 0x90, 0x90,		// A
+    0xE0, 0x90, 0xE0, 0x90, 0xE0,		// B
+    0xF0, 0x80, 0x80, 0x80, 0xF0,		// C
+    0xE0, 0x90, 0x90, 0x90, 0xE0,		// D
+    0xF0, 0x80, 0xF0, 0x80, 0xF0,		// E
+    0xF0, 0x80, 0xF0, 0x80, 0x80		// F
+}
+
+init :: proc() -> System {
+    log.info("Booting chip 8 cpu")
+
+    // Structs are zero initialized so timers, sp etc are good.
+    s := System { pc = 0x200 }
+
+    // load fonts into the memory
+    for v, i in FONT_SET {
+        s.memory[i] = v
+    }
+
+    return s
+}
+
+load_rom :: proc(s: ^System, file_path: string) -> os.Error {
+    log.info("Loading rom from file")
+
+    data, read_err := os.read_entire_file(file_path, context.allocator)
+    if read_err != os.ERROR_NONE {
+        log.errorf("failed to read rom %v", read_err)
+        return read_err
+    }
+    defer delete(data)
+
+    for byte,i in data {
+        s.memory[0x200 + i] = byte
+    }
+
+    log.infof("First few bytes: %X %X %X %X", s.memory[0x200], s.memory[0x201], s.memory[0x202], s.memory[0x203])
+
+    return nil
+}
+
+// fetch decode execute loop
+run :: proc(s: ^System) {
+    log.info("=== TODO loop ===")
+    // maybe needs a few functions for the 'screen' ie raylib.
+    // also a cycle function or something that will do the ops
+}
+