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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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10
src/cpu/thumb/format16.zig
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@@ -3,20 +3,24 @@ const std = @import("std");
const Bus = @import("../../Bus.zig");
const Arm7tdmi = @import("../../cpu.zig").Arm7tdmi;
const InstrFn = @import("../../cpu.zig").ThumbInstrFn;
const checkCond = @import("../../cpu.zig").checkCond;
const u32SignExtend = @import("../../util.zig").u32SignExtend;
pub fn format16(comptime cond: u4) InstrFn {
return struct {
fn inner(cpu: *Arm7tdmi, _: *Bus, opcode: u16) void {
const offset = (opcode & 0xFF) << 1;
// B
const offset = u32SignExtend(8, opcode & 0xFF) << 1;
const do_execute = switch (cond) {
const should_execute = switch (cond) {
0xE, 0xF => std.debug.panic("[CPU/THUMB] Undefined conditional branch with condition {}", .{cond}),
else => checkCond(cpu.cpsr, cond),
};
if (do_execute) cpu.r[15] = (cpu.fakePC() & 0xFFFF_FFFC) +% u32SignExtend(8, offset);
if (should_execute) {
cpu.r[15] = (cpu.fakePC() & 0xFFFF_FFFC) +% offset;
}
}
}.inner;
}