Binary uint8 reversal

Author: BenderScript

binary_uint8_reversal/main.go

@@ -0,0 +1,56 @@
+/*
+Binary integer order reversal. This is twist on the well-known string reversal. The idea is to swap
+the actual bits.
+
+Go has a function that provides this functionality but this is home grown
+
+*/
+
+package main
+
+import (
+	"fmt"
+)
+
+type test struct {
+	original uint8
+	expected uint8
+}
+
+var tests []test
+
+func main() {
+
+	for _, t := range tests {
+		reversed := reverseUInt8(t)
+		if reversed == t.expected {
+			fmt.Printf("%d is the reverse of %d \n", t.expected, t.original)
+		} else {
+			panic("Not properly reversed")
+		}
+	}
+}
+
+func reverseUInt8(t test) (rev uint8) {
+	var oneUint8, bit uint8
+	oneUint8 = byte(0b00000001)
+
+	rev = t.original
+	for n := 7; n >= 4; n-- {
+		lBit := (rev >> n) & oneUint8
+		rBit := (rev >> (7 - n)) & oneUint8
+		// Could actually be a constant
+		bit = ^(oneUint8 << (7 - n)) //all ones but one bit
+		rev = (rev & bit) | lBit<<(7-n)
+		bit = ^(oneUint8 << n) //all ones but one bit
+		rev = (rev & bit) | rBit<<n
+	}
+	return
+}
+
+func init() {
+	tests = append(tests, test{85, 170})
+	tests = append(tests, test{0, 0})
+	tests = append(tests, test{255, 255})
+	tests = append(tests, test{240, 15})
+}