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chore: implement more than just 1 cycle per mem access

This commit is contained in:
Rekai Nyangadzayi Musuka 2022-06-16 22:35:42 -03:00
parent cc8c1c1e21
commit 460f8308a7
2 changed files with 19 additions and 2 deletions
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17
src/Bus.zig
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@ -21,6 +21,19 @@ const log = std.log.scoped(.Bus);
const createDmaTuple = @import("bus/dma.zig").create;
const createTimerTuple = @import("bus/timer.zig").create;
const rotr = @import("util.zig").rotr;
const timings: [2][0x10]u8 = [_][0x10]u8{
// BIOS, Unused, EWRAM, IWRAM, I/0, PALRAM, VRAM, OAM, ROM0, ROM0, ROM1, ROM1, ROM2, ROM2, SRAM, Unused
[_]u8{ 1, 1, 3, 1, 1, 1, 1, 1, 5, 5, 5, 5, 5, 5, 5, 5 }, // 8-bit & 16-bit
[_]u8{ 1, 1, 6, 1, 1, 2, 2, 1, 8, 8, 8, 8, 8, 8, 8, 8 }, // 32-bit
};
pub const fetch_timings: [2][0x10]u8 = [_][0x10]u8{
// BIOS, Unused, EWRAM, IWRAM, I/0, PALRAM, VRAM, OAM, ROM0, ROM0, ROM1, ROM1, ROM2, ROM2, SRAM, Unused
[_]u8{ 1, 1, 3, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 5, 5 }, // 8-bit & 16-bit
[_]u8{ 1, 1, 6, 1, 1, 2, 2, 1, 4, 4, 4, 4, 4, 4, 8, 8 }, // 32-bit
};
const Self = @This();
pak: GamePak,
@ -112,7 +125,7 @@ fn readBios(self: *Self, comptime T: type, address: u32) T {
pub fn read(self: *Self, comptime T: type, address: u32) T {
const page = @truncate(u8, address >> 24);
const align_addr = alignAddress(T, address);
self.sched.tick += 1;
defer self.sched.tick += timings[@boolToInt(T == u32)][@truncate(u4, page)];
return switch (page) {
// General Internal Memory
@ -147,7 +160,7 @@ pub fn read(self: *Self, comptime T: type, address: u32) T {
pub fn write(self: *Self, comptime T: type, address: u32, value: T) void {
const page = @truncate(u8, address >> 24);
const align_addr = alignAddress(T, address);
self.sched.tick += 1;
defer self.sched.tick += timings[@boolToInt(T == u32)][@truncate(u4, page)];
switch (page) {
// General Internal Memory

4
src/cpu.zig
View File

@ -330,6 +330,10 @@ pub const Arm7tdmi = struct {
comptime std.debug.assert(T == u32 or T == u16); // Opcode may be 32-bit (ARM) or 16-bit (THUMB)
defer self.r[15] += if (T == u32) 4 else 2;
// FIXME: You better hope this is optimized out
const tick_cache = self.sched.tick;
defer self.sched.tick = tick_cache + Bus.fetch_timings[@boolToInt(T == u32)][@truncate(u4, self.r[15] >> 24)];
return self.bus.read(T, self.r[15]);
}