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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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46
src/cpu/thumb/format3.zig
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@@ -4,6 +4,11 @@ const Bus = @import("../../Bus.zig");
const Arm7tdmi = @import("../../cpu.zig").Arm7tdmi;
const InstrFn = @import("../../cpu.zig").ThumbInstrFn;
const add = @import("../arm/data_processing.zig").add;
const sub = @import("../arm/data_processing.zig").sub;
const cmp = @import("../arm/data_processing.zig").cmp;
const setLogicOpFlags = @import("../arm/data_processing.zig").setLogicOpFlags;
pub fn format3(comptime op: u2, comptime rd: u3) InstrFn {
return struct {
fn inner(cpu: *Arm7tdmi, _: *Bus, opcode: u16) void {
@@ -13,44 +18,11 @@ pub fn format3(comptime op: u2, comptime rd: u3) InstrFn {
0b00 => {
// MOV
cpu.r[rd] = offset;
cpu.cpsr.n.unset();
cpu.cpsr.z.write(offset == 0);
},
0b01 => {
// CMP
const left = cpu.r[rd];
const result = left -% offset;
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
cpu.cpsr.c.write(offset <= left);
cpu.cpsr.v.write(((left ^ result) & (~offset ^ result)) >> 31 & 1 == 1);
},
0b10 => {
// ADD
const left = cpu.r[rd];
var result: u32 = undefined;
const didOverflow = @addWithOverflow(u32, left, offset, &result);
cpu.r[rd] = result;
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
cpu.cpsr.c.write(didOverflow);
cpu.cpsr.v.write(((left ^ result) & (offset ^ result)) >> 31 & 1 == 1);
},
0b11 => {
// SUB
const left = cpu.r[rd];
const result = left -% offset;
cpu.r[rd] = result;
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
cpu.cpsr.c.write(offset <= left);
cpu.cpsr.v.write(((left ^ result) & (~offset ^ result)) >> 31 & 1 == 1);
setLogicOpFlags(true, cpu, offset);
},
0b01 => cmp(cpu, cpu.r[rd], offset), // CMP
0b10 => cpu.r[rd] = add(true, cpu, cpu.r[rd], offset), // ADD
0b11 => cpu.r[rd] = sub(true, cpu, cpu.r[rd], offset), // SUB
}
}
}.inner;