28 lines
837 B
Zig
28 lines
837 B
Zig
const std = @import("std");
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const util = @import("../../util.zig");
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const Bus = @import("../../Bus.zig");
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const Arm7tdmi = @import("../../cpu.zig").Arm7tdmi;
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const InstrFn = @import("../../cpu.zig").InstrFn;
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pub fn branch(comptime L: bool) InstrFn {
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return struct {
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fn inner(cpu: *Arm7tdmi, _: *Bus, opcode: u32) void {
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if (L) {
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// TODO: Debugging beeg.gba w/ MGBA seems to suggest that I don't do anything here
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cpu.r[14] = cpu.r[15];
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}
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cpu.r[15] = cpu.fakePC() +% util.u32SignExtend(24, opcode << 2);
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}
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}.inner;
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}
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pub fn branchAndExchange(cpu: *Arm7tdmi, _: *Bus, opcode: u32) void {
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const rn = opcode & 0xF;
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cpu.cpsr.t.write(cpu.r[rn] & 1 == 1);
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// TODO: Is this how I should do it?
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cpu.r[15] = cpu.r[rn] & 0xFFFF_FFFE;
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}
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