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

feat(cpu): implement format2 THUMB instructions

Browse Source
This commit is contained in:
Rekai Nyangadzayi Musuka
2022-01-29 18:46:27 -04:00
parent 4ca65caef0
commit 599e068c7e
3 changed files with 61 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
src/cpu/arm/data_processing.zig
View File

@@ -43,23 +43,7 @@ pub fn dataProcessing(comptime I: bool, comptime S: bool, comptime instrKind: u4
},
0x2 => cpu.r[rd] = sub(S, cpu, rd, op1, op2), // SUB
0x3 => cpu.r[rd] = sub(S, cpu, rd, op2, op1), // RSB
0x4 => {
// ADD
var result: u32 = undefined;
const didOverflow = @addWithOverflow(u32, op1, op2, &result);
cpu.r[rd] = result;
if (S) {
if (rd == 0xF) {
cpu.setCpsr(cpu.spsr.raw);
} else {
cpu.cpsr.n.write(result >> 31 & 1 == 1);
cpu.cpsr.z.write(result == 0);
cpu.cpsr.c.write(didOverflow);
cpu.cpsr.v.write(((op1 ^ result) & (op2 ^ result)) >> 31 & 1 == 1);
}
}
},
0x4 => cpu.r[rd] = add(S, cpu, rd, op1, op2), // ADD
0x5 => {
// ADC
var result: u32 = undefined;
@@ -181,7 +165,7 @@ fn sbc(comptime S: bool, cpu: *Arm7tdmi, rd: u4, left: u32, right: u32, old_carr
return result;
}
fn sub(comptime S: bool, cpu: *Arm7tdmi, rd: u4, left: u32, right: u32) u32 {
pub fn sub(comptime S: bool, cpu: *Arm7tdmi, rd: u4, left: u32, right: u32) u32 {
const result = left -% right;
if (S) {
@@ -198,6 +182,24 @@ fn sub(comptime S: bool, cpu: *Arm7tdmi, rd: u4, left: u32, right: u32) u32 {
return result;
}
pub fn add(comptime S: bool, cpu: *Arm7tdmi, rd: u4, left: u32, right: u32) u32 {
var result: u32 = undefined;
const didOverflow = @addWithOverflow(u32, left, right, &result);
if (S) {
if (rd == 0xF) {
cpu.setCpsr(cpu.spsr.raw);
} else {
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) & (right ^ result)) >> 31 & 1 == 1);
}
}
return result;
}
fn logicFlags(comptime S: bool, cpu: *Arm7tdmi, rd: u4, result: u32) void {
if (S) {
if (rd == 0xF) {