Implement micro optimisations for unary operators

A 1% speed increase was observed when testing a tight decrementing loop
with these optimisations.

1 files changed, 36 insertions, 0 deletions

diff --git a/src/stack.rs b/src/stack.rs
index 14e1799..2862b72 100644
--- a/src/stack.rs
+++ b/src/stack.rs
@@ -50,3 +50,39 @@ impl Stack {
         self.sp = 0;
     }
 }
+
+use std::ops::Not;
+
+impl Stack {
+    pub fn inc_u8(&mut self) {
+        let sp = self.sp.wrapping_sub(1) as usize;
+        self.mem[sp] = self.mem[sp].wrapping_add(1);
+    }
+
+    pub fn dec_u8(&mut self) {
+        let sp = self.sp.wrapping_sub(1) as usize;
+        self.mem[sp] = self.mem[sp].wrapping_sub(1);
+    }
+
+    pub fn not_u8(&mut self) {
+        let sp = self.sp.wrapping_sub(1) as usize;
+        self.mem[sp] = self.mem[sp].not();
+    }
+
+    pub fn not_u16(&mut self) {
+        let sp = self.sp.wrapping_sub(1) as usize;
+        self.mem[sp] = self.mem[sp].not();
+        let sp = self.sp.wrapping_sub(2) as usize;
+        self.mem[sp] = self.mem[sp].not();
+    }
+
+    pub fn tal_u8(&mut self) {
+        let sp = self.sp.wrapping_sub(1) as usize;
+        self.mem[sp] = self.mem[sp].count_ones() as u8;
+    }
+
+    pub fn rev_u8(&mut self) {
+        let sp = self.sp.wrapping_sub(1) as usize;
+        self.mem[sp] = self.mem[sp].reverse_bits();
+    }
+}