Merge pull request #49 from FlorianWendelborn/0xflotus-circular-shift

feature(#44): Add Circular Shift

readme.md

@@ -59,7 +59,7 @@ or
 ## Table of Contents
 
 - [bits](#bits)
-  - operations ([and](#bitsand), [nand](#bitsnand), [nor](#bitsnor), [not](#bitsnot), [or](#bitsor), [xnor](#bitsxnor), [xor](#bitsxor))
+  - operations ([and](#bitsand), [circularShiftLeft](#bitscircularshiftleft), [circularShiftRight](#bitscircularshiftright), [nand](#bitsnand), [nor](#bitsnor), [not](#bitsnot), [or](#bitsor), [xnor](#bitsxnor), [xor](#bitsxor))
   - reduce operations ([reduceAnd](#bitsreduceand), [reduceNand](#bitsreducenand), [reduceNor](#bitsreducenor), [reduceOr](#bitsreduceor), [reduceXnor](#bitsreducexnor), [reduceXor](#bitsreducexor))
   - [toString](#bitstostring)
 - [buffer](#buffer)
@@ -104,6 +104,32 @@ bitwise.bits.and([1, 0, 0, 0, 1, 1, 0, 1], [0, 1, 1, 0, 0, 1, 0, 0])
 // [0, 0, 0, 0, 0, 1, 0, 0]
 ```
 
+### bits.circularShiftLeft
+
+```ts
+(bits: Array<0|1>, amount: number): Array<0|1>
+```
+
+Applies the bitwise `ROL` operation, expects two arrays of the same size and a shift amount and returns a new one.
+
+```js
+bitwise.bits.circularShiftLeft([0, 0, 0, 1, 1, 1, 1, 1], 1)
+// [0, 0, 1, 1, 1, 1, 1, 0]
+```
+
+### bits.circularShiftRight
+
+```ts
+(bits: Array<0|1>, amount: number): Array<0|1>
+```
+
+Applies the bitwise `ROR` operation, expects two arrays of the same size and a shift amount and returns a new one.
+
+```js
+bitwise.bits.circularShiftRight([0, 0, 0, 1, 1, 1, 1, 1], 1)
+// [1, 0, 0, 0, 1, 1, 1, 1]
+```
+
 ### bits.nand
 
 ```ts

source/bits/circular-shift-left.test.ts

@@ -0,0 +1,54 @@
+import { Bits } from '../types'
+import circularShiftLeft from './circular-shift-left'
+
+test('circularShiftLeft with amount 1', () => {
+	const testCases: Array<[Bits, Bits]> = [
+		[
+			[1, 0, 0, 0, 1, 1, 0, 1],
+			[0, 0, 0, 1, 1, 0, 1, 1],
+		],
+		[
+			[0, 0, 0, 1, 1, 1, 1, 1],
+			[0, 0, 1, 1, 1, 1, 1, 0],
+		],
+	]
+
+	for (const [input, expectedResult] of testCases)
+		expect(circularShiftLeft(input, 1)).toEqual(expectedResult)
+})
+
+test('circularShiftLeft with amount 2', () => {
+	const testCases: Array<[Bits, Bits]> = [
+		[
+			[1, 0, 0, 0, 1, 1, 0, 1],
+			[0, 0, 1, 1, 0, 1, 1, 0],
+		],
+		[
+			[0, 0, 0, 1, 1, 1, 1, 1],
+			[0, 1, 1, 1, 1, 1, 0, 0],
+		],
+	]
+
+	for (const [input, expectedResult] of testCases)
+		expect(circularShiftLeft(input, 2)).toEqual(expectedResult)
+})
+
+test('circularShiftLeft with amount 3', () => {
+	const testCases: Array<[Bits, Bits]> = [
+		[
+			[1, 0, 0, 0, 1, 1, 0, 1],
+			[0, 1, 1, 0, 1, 1, 0, 0],
+		],
+		[
+			[0, 0, 0, 1, 1, 1, 1, 1],
+			[1, 1, 1, 1, 1, 0, 0, 0],
+		],
+	]
+
+	for (const [input, expectedResult] of testCases)
+		expect(circularShiftLeft(input, 3)).toEqual(expectedResult)
+})
+
+test('circularShiftLeft throws when amount too large', () => {
+	expect(() => circularShiftLeft([0, 1], 3)).toThrow()
+})

source/bits/circular-shift-left.ts

@@ -0,0 +1,25 @@
+import { Bits } from '../types'
+
+/**
+ * Circular Shift Left
+ *
+ * @example
+ * circularShiftLeft([1,0,1,1,0,1]) => [0,1,1,0,1,1]
+ *
+ * @see {@link https://en.wikipedia.org/wiki/Circular_shift}
+ *
+ * @param {Array} bits input data
+ * @param {number} amount how far should it be shifted
+ * @return {Array} [ROL bits]
+ */
+export default (bits: Bits, amount: number): Bits => {
+	const result: Bits = []
+
+	if (amount > bits.length)
+		throw new Error('shift amount can’t be larger than bits array length')
+
+	for (let i = 0; i < bits.length; i++)
+		result[(bits.length + i - amount) % bits.length] = bits[i]
+
+	return result
+}

source/bits/circular-shift-right.test.ts

@@ -0,0 +1,54 @@
+import { Bits } from '../types'
+import circularShiftRight from './circular-shift-right'
+
+test('circularShiftRight with amount 1', () => {
+	const testCases: Array<[Bits, Bits]> = [
+		[
+			[1, 0, 0, 0, 1, 1, 0, 1],
+			[1, 1, 0, 0, 0, 1, 1, 0],
+		],
+		[
+			[0, 0, 0, 1, 1, 1, 1, 1],
+			[1, 0, 0, 0, 1, 1, 1, 1],
+		],
+	]
+
+	for (const [input, expectedResult] of testCases)
+		expect(circularShiftRight(input, 1)).toEqual(expectedResult)
+})
+
+test('circularShiftRight with amount 2', () => {
+	const testCases: Array<[Bits, Bits]> = [
+		[
+			[1, 0, 0, 0, 1, 1, 0, 1],
+			[0, 1, 1, 0, 0, 0, 1, 1],
+		],
+		[
+			[0, 0, 0, 1, 1, 1, 1, 1],
+			[1, 1, 0, 0, 0, 1, 1, 1],
+		],
+	]
+
+	for (const [input, expectedResult] of testCases)
+		expect(circularShiftRight(input, 2)).toEqual(expectedResult)
+})
+
+test('circularShiftRight with amount 3', () => {
+	const testCases: Array<[Bits, Bits]> = [
+		[
+			[1, 0, 0, 0, 1, 1, 0, 1],
+			[1, 0, 1, 1, 0, 0, 0, 1],
+		],
+		[
+			[0, 0, 0, 1, 1, 1, 1, 1],
+			[1, 1, 1, 0, 0, 0, 1, 1],
+		],
+	]
+
+	for (const [input, expectedResult] of testCases)
+		expect(circularShiftRight(input, 3)).toEqual(expectedResult)
+})
+
+test('circularShiftRight throws when amount too large', () => {
+	expect(() => circularShiftRight([0, 1], 3)).toThrow()
+})

source/bits/circular-shift-right.ts

@@ -0,0 +1,25 @@
+import { Bits } from '../types'
+
+/**
+ * Circular Shift Right
+ *
+ * @example
+ * circularShiftRight([1,0,1,1,0,1]) => [1,1,0,1,1,0]
+ *
+ * @see {@link https://en.wikipedia.org/wiki/Circular_shift}
+ *
+ * @param {Array} bits input data
+ * @param {number} amount how far should it be shifted
+ * @return {Array} [ROR bits]
+ */
+export default (bits: Bits, amount: number): Bits => {
+	const result: Bits = []
+
+	if (amount > bits.length)
+		throw new Error('shift amount can’t be larger than bits array length')
+
+	for (let i = 0; i < bits.length; i++)
+		result[(i + amount) % bits.length] = bits[i]
+
+	return result
+}

source/bits/index.ts

@@ -1,4 +1,6 @@
 import and from './and'
+import circularShiftLeft from './circular-shift-left'
+import circularShiftRight from './circular-shift-right'
 import nand from './nand'
 import nor from './nor'
 import not from './not'
@@ -16,6 +18,8 @@ import xor from './xor'
 
 export {
 	and,
+	circularShiftLeft,
+	circularShiftRight,
 	nand,
 	nor,
 	not,
@@ -34,6 +38,8 @@ export {
 
 export default {
 	and,
+	circularShiftLeft,
+	circularShiftRight,
 	nand,
 	nor,
 	not,