From f3c77f5a31a3d9ba6ba559316b26e565417aa0eb Mon Sep 17 00:00:00 2001
From: Ben Bridle <bridle.benjamin@gmail.com>
Date: Sat, 18 May 2024 10:31:47 +1200
Subject: Fix SHF instruction
The wrong shifting operation was being used for the SHF operation. The
'wrapping' operations were shifting by the given distance, modulo eight,
which was yielding incorrect results for shift distances greater than
seven.
---
src/processor.rs | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
(limited to 'src')
diff --git a/src/processor.rs b/src/processor.rs
index cb1b2d5..9c9fb45 100644
--- a/src/processor.rs
+++ b/src/processor.rs
@@ -47,7 +47,7 @@ impl<D: DeviceBus> Processor<D> {
macro_rules! pc { () => { self.mem.read_pc() }; }
macro_rules! truth { ($x:expr) => { if $x {0xff} else {0x00} }; }
macro_rules! nyb { ($v:expr=>$h:ident,$l:ident) => { let $h=($v>>4); let $l=($v&0x0f); } }
- macro_rules! shf { ($x:expr,$y:expr) => { { nyb!($y=>l,r); $x.wrapping_shl(l as u32).wrapping_shr(r as u32) } } ; }
+ macro_rules! shf { ($x:expr,$y:expr) => { { nyb!($y=>l,r); $x.checked_shl(l as u32).unwrap_or(0).checked_shr(r as u32).unwrap_or(0) } } ; }
macro_rules! shc { ($x:expr,$y:expr) => { { nyb!($y=>l,r); $x.rotate_left( l as u32).rotate_right(r as u32) } }; }
for _ in 0..num_cycles {
--
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