chore: replace unnecessarily complex sign extension implementation

This commit is contained in:
2022-02-28 20:38:50 -04:00
parent ddb68a7952
commit cb4d3a9a51
6 changed files with 19 additions and 41 deletions

View File

@@ -4,7 +4,7 @@ const Bus = @import("../../Bus.zig");
const Arm7tdmi = @import("../../cpu.zig").Arm7tdmi;
const InstrFn = @import("../../cpu.zig").ArmInstrFn;
const u32SignExtend = @import("../../util.zig").u32SignExtend;
const sext = @import("../../util.zig").sext;
pub fn halfAndSignedDataTransfer(comptime P: bool, comptime U: bool, comptime I: bool, comptime W: bool, comptime L: bool) InstrFn {
return struct {
@@ -42,14 +42,14 @@ pub fn halfAndSignedDataTransfer(comptime P: bool, comptime U: bool, comptime I:
},
0b10 => {
// LDRSB
result = u32SignExtend(8, bus.read8(address));
result = sext(8, bus.read8(address));
},
0b11 => {
// LDRSH
const value = if (address & 1 == 1) blk: {
break :blk u32SignExtend(8, bus.read8(address));
break :blk sext(8, bus.read8(address));
} else blk: {
break :blk u32SignExtend(16, bus.read16(address));
break :blk sext(16, bus.read16(address));
};
result = std.math.rotr(u32, value, 8 * (address & 1));