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fix(cpu): allow for select values to overflow 

FuzzARM found these operations which panicked, when they should
have overflowed. These are now fixed

n = 8000
This commit is contained in:
Rekai Nyangadzayi Musuka 2022-10-21 05:12:12 -03:00
parent af10c1b076
commit b4e0682801
2 changed files with 3 additions and 3 deletions
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2
src/cpu/arm/data_processing.zig
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@ -145,7 +145,7 @@ fn armSbc(comptime S: bool, cpu: *Arm7tdmi, rd: u4, left: u32, right: u32, old_c
pub fn sbc(comptime S: bool, cpu: *Arm7tdmi, left: u32, right: u32, old_carry: u1) u32 {
// TODO: Make your own version (thanks peach.bot)
const subtrahend = @as(u64, right) - old_carry + 1;
const subtrahend = @as(u64, right) -% old_carry +% 1;
const result = @truncate(u32, left -% subtrahend);
if (S) {

4
src/cpu/arm/multiply_long.zig
View File

@ -15,14 +15,14 @@ pub fn multiplyLong(comptime U: bool, comptime A: bool, comptime S: bool) InstrF
if (U) {
// Signed (WHY IS IT U THEN?)
var result: i64 = @as(i64, @bitCast(i32, cpu.r[rm])) * @as(i64, @bitCast(i32, cpu.r[rs]));
if (A) result += @bitCast(i64, @as(u64, cpu.r[rd_hi]) << 32 | @as(u64, cpu.r[rd_lo]));
if (A) result +%= @bitCast(i64, @as(u64, cpu.r[rd_hi]) << 32 | @as(u64, cpu.r[rd_lo]));
cpu.r[rd_hi] = @bitCast(u32, @truncate(i32, result >> 32));
cpu.r[rd_lo] = @bitCast(u32, @truncate(i32, result));
} else {
// Unsigned
var result: u64 = @as(u64, cpu.r[rm]) * @as(u64, cpu.r[rs]);
if (A) result += @as(u64, cpu.r[rd_hi]) << 32 | @as(u64, cpu.r[rd_lo]);
if (A) result +%= @as(u64, cpu.r[rd_hi]) << 32 | @as(u64, cpu.r[rd_lo]);
cpu.r[rd_hi] = @truncate(u32, result >> 32);
cpu.r[rd_lo] = @truncate(u32, result);