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.

1 files changed, 1 insertions, 1 deletions

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 {