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chore: dedup code in THUMB instructions

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This commit is contained in:
Rekai Nyangadzayi Musuka
2022-01-29 20:05:27 -04:00
parent bce067557f
commit ae4023e51c
8 changed files with 33 additions and 62 deletions
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16
src/cpu/thumb/format5.zig
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@@ -4,6 +4,8 @@ const Bus = @import("../../Bus.zig");
const Arm7tdmi = @import("../../cpu.zig").Arm7tdmi;
const InstrFn = @import("../../cpu.zig").ThumbInstrFn;
const cmp = @import("../arm/data_processing.zig").cmp;
pub fn format5(comptime op: u2, comptime h1: u1, comptime h2: u1) InstrFn {
return struct {
fn inner(cpu: *Arm7tdmi, _: *Bus, opcode: u16) void {
@@ -11,24 +13,14 @@ pub fn format5(comptime op: u2, comptime h1: u1, comptime h2: u1) InstrFn {
const dst = @as(u4, h1) << 3 | (opcode & 0x7);
switch (op) {
0b01 => {
// CMP
const left = cpu.r[dst];
const right = cpu.r[src];
const result = left -% right;
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
cpu.cpsr.c.write(right <= left);
cpu.cpsr.v.write(((left ^ result) & (~right ^ result)) >> 31 & 1 == 1);
},
0b01 => cmp(cpu, cpu.r[dst], cpu.r[src]), // CMP
0b10 => cpu.r[dst] = cpu.r[src], // MOV
0b11 => {
// BX
cpu.cpsr.t.write(cpu.r[src] & 1 == 1);
cpu.r[15] = cpu.r[src] & 0xFFFF_FFFE;
},
else => std.debug.panic("[CPU] Op #{} is invalid for THUMB Format 5", .{op}),
else => std.debug.panic("[CPU|THUMB|Fmt5] {} is an invalid op", .{op}),
}
}
}.inner;