paoda/zba
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

feat: implement S (when rd != 15) for several data processing instructions

Browse Source
This commit is contained in:
Rekai Nyangadzayi Musuka
2022-01-05 15:45:52 -05:00
parent 28a70d0112
commit 5037b8f0cc
3 changed files with 52 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
src/cpu/barrel_shifter.zig
View File

@@ -4,7 +4,7 @@ const arm = @import("../cpu.zig");
const Arm7tdmi = arm.Arm7tdmi;
const CPSR = arm.CPSR;
pub inline fn exec(cpu: *Arm7tdmi, opcode: u32) u32 {
pub inline fn exec(comptime S: bool, cpu: *Arm7tdmi, opcode: u32) u32 {
var shift_amt: u8 = undefined;
if (opcode >> 4 & 1 == 1) {
shift_amt = @truncate(u8, cpu.r[opcode >> 8 & 0xF]);
@@ -14,12 +14,22 @@ pub inline fn exec(cpu: *Arm7tdmi, opcode: u32) u32 {
const rm = cpu.r[opcode & 0xF];
return switch (@truncate(u2, opcode >> 5)) {
0b00 => logical_left(&cpu.cpsr, rm, shift_amt),
0b01 => logical_right(&cpu.cpsr, rm, shift_amt),
0b10 => arithmetic_right(&cpu.cpsr, rm, shift_amt),
0b11 => rotate_right(&cpu.cpsr, rm, shift_amt),
};
if (S) {
return switch (@truncate(u2, opcode >> 5)) {
0b00 => logical_left(&cpu.cpsr, rm, shift_amt),
0b01 => logical_right(&cpu.cpsr, rm, shift_amt),
0b10 => arithmetic_right(&cpu.cpsr, rm, shift_amt),
0b11 => rotate_right(&cpu.cpsr, rm, shift_amt),
};
} else {
var dummy = CPSR{ .raw = 0x0000_0000 };
return switch (@truncate(u2, opcode >> 5)) {
0b00 => logical_left(&dummy, rm, shift_amt),
0b01 => logical_right(&dummy, rm, shift_amt),
0b10 => arithmetic_right(&dummy, rm, shift_amt),
0b11 => rotate_right(&dummy, rm, shift_amt),
};
}
}
pub inline fn logical_left(cpsr: *CPSR, rm: u32, shift_byte: u8) u32 {