28 lines
763 B
Zig
28 lines
763 B
Zig
const std = @import("std");
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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").ArmInstrFn;
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const sext = @import("../../util.zig").sext;
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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) cpu.r[14] = cpu.r[15] - 4;
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cpu.r[15] +%= sext(u32, u24, opcode) << 2;
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cpu.pipe.flush();
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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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const thumb = cpu.r[rn] & 1 == 1;
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cpu.r[15] = cpu.r[rn] & if (thumb) ~@as(u32, 1) else ~@as(u32, 3);
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cpu.cpsr.t.write(thumb);
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cpu.pipe.flush();
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}
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