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Bit query and bit rotation functions for Int, Long, Short, Byte

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#KT-12749
This commit is contained in:
Ilya Gorbunov
2019-05-05 06:15:00 +03:00
parent 32fc131d62
commit f8724654a1
8 changed files with 836 additions and 3 deletions
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libraries/stdlib/test/numbers/NumbersTest.kt
+192 -1
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@@ -5,6 +5,7 @@
package test.numbers
import kotlin.random.Random
import kotlin.test.*
object NumbersTestConstants {
@@ -199,6 +200,196 @@ class NumbersTest {
testSizes(UShort, UShort.SIZE_BYTES, UShort.SIZE_BITS, 2)
testSizes(UInt, UInt.SIZE_BYTES, UInt.SIZE_BITS, 4)
testSizes(ULong, ULong.SIZE_BYTES, ULong.SIZE_BITS, 8)
}
}
@Test
fun byteBits() {
fun test(value: Byte, oneBits: Int, leadingZeroes: Int, trailingZeroes: Int) {
assertEquals(oneBits, value.countOneBits())
assertEquals(leadingZeroes, value.countLeadingZeroBits())
assertEquals(trailingZeroes, value.countTrailingZeroBits())
val highestBit = if (leadingZeroes < Byte.SIZE_BITS) 1.shl(Byte.SIZE_BITS - leadingZeroes - 1).toByte() else 0
val lowestBit = if (trailingZeroes < Byte.SIZE_BITS) 1.shl(trailingZeroes).toByte() else 0
assertEquals(highestBit, value.takeHighestOneBit())
assertEquals(lowestBit, value.takeLowestOneBit())
}
test(0, 0, 8, 8)
test(1, 1, 7, 0)
test(2, 1, 6, 1)
test(0x44, 2, 1, 2)
test(0x80.toByte(), 1, 0, 7)
test(0xF0.toByte(), 4, 0, 4)
}
@Test
fun shortBits() {
fun test(value: Short, oneBits: Int, leadingZeroes: Int, trailingZeroes: Int) {
assertEquals(oneBits, value.countOneBits())
assertEquals(leadingZeroes, value.countLeadingZeroBits())
assertEquals(trailingZeroes, value.countTrailingZeroBits())
val highestBit = if (leadingZeroes < Short.SIZE_BITS) 1.shl(Short.SIZE_BITS - leadingZeroes - 1).toShort() else 0
val lowestBit = if (trailingZeroes < Short.SIZE_BITS) 1.shl(trailingZeroes).toShort() else 0
assertEquals(highestBit, value.takeHighestOneBit())
assertEquals(lowestBit, value.takeLowestOneBit())
}
test(0, 0, 16, 16)
test(1, 1, 15, 0)
test(2, 1, 14, 1)
test(0xF2, 5, 8, 1)
test(0x8000.toShort(), 1, 0, 15)
test(0xF200.toShort(), 5, 0, 9)
}
@Test
fun intBits() {
fun test(value: Int, oneBits: Int, leadingZeroes: Int, trailingZeroes: Int) {
assertEquals(oneBits, value.countOneBits())
assertEquals(leadingZeroes, value.countLeadingZeroBits())
assertEquals(trailingZeroes, value.countTrailingZeroBits())
val highestBit = if (leadingZeroes < Int.SIZE_BITS) 1.shl(Int.SIZE_BITS - leadingZeroes - 1) else 0
val lowestBit = if (trailingZeroes < Int.SIZE_BITS) 1.shl(trailingZeroes) else 0
assertEquals(highestBit, value.takeHighestOneBit())
assertEquals(lowestBit, value.takeLowestOneBit())
}
test(0, 0, 32, 32)
test(1, 1, 31, 0)
test(2, 1, 30, 1)
test(0xF002, 5, 16, 1)
test(0xF00F0000.toInt(), 8, 0, 16)
}
@Test
fun longBits() {
fun test(value: Long, oneBits: Int, leadingZeroes: Int, trailingZeroes: Int) {
assertEquals(oneBits, value.countOneBits())
assertEquals(leadingZeroes, value.countLeadingZeroBits())
assertEquals(trailingZeroes, value.countTrailingZeroBits())
val highestBit = if (leadingZeroes < Long.SIZE_BITS) 1L.shl(Long.SIZE_BITS - leadingZeroes - 1).toLong() else 0
val lowestBit = if (trailingZeroes < Long.SIZE_BITS) 1L.shl(trailingZeroes).toLong() else 0
assertEquals(highestBit, value.takeHighestOneBit())
assertEquals(lowestBit, value.takeLowestOneBit())
}
test(0, 0, 64, 64)
test(1, 1, 63, 0)
test(2, 1, 62, 1)
test(0xF002, 5, 48, 1)
test(0xF00F0000L, 8, 32, 16)
test(0x1111_3333_EEEE_0000L, 4 + 8 + 12, 3, 17)
}
@Test
fun intRotate() {
fun test(value: Int, n: Int, expected: Int) {
assertEquals(expected, value.rotateLeft(n))
assertEquals(expected, value.rotateRight(-n))
}
fun testCyclic(value: Int) {
for (n in -2 * Int.SIZE_BITS..2 * Int.SIZE_BITS) {
val rl = value.rotateLeft(n)
val rr = value.rotateRight(-n)
assertEquals(rl, rr)
assertEquals(rl, value.rotateLeft(n % Int.SIZE_BITS))
assertEquals(rr, value.rotateRight((-n) % Int.SIZE_BITS))
assertEquals(value, value.rotateLeft(n).rotateLeft(-n))
assertEquals(value, value.rotateRight(n).rotateRight(-n))
}
}
test(0x7_3422345, 4, 0x3422345_7)
test(0x7342234_5, -4, 0x5_7342234)
test(0x73422345, 1, 0xE684468A.toInt())
repeat(100) {
testCyclic(Random.nextInt())
}
}
@Test
fun byteRotate() {
fun test(value: Byte, n: Int, expected: Byte) {
assertEquals(expected, value.rotateLeft(n))
assertEquals(expected, value.rotateRight(-n))
}
fun testCyclic(value: Byte) {
for (n in -2 * Byte.SIZE_BITS..2 * Byte.SIZE_BITS) {
val rl = value.rotateLeft(n)
val rr = value.rotateRight(-n)
assertEquals(rl, rr)
assertEquals(rl, value.rotateLeft(n % Byte.SIZE_BITS))
assertEquals(rr, value.rotateRight((-n) % Byte.SIZE_BITS))
assertEquals(value, value.rotateLeft(n).rotateLeft(-n))
assertEquals(value, value.rotateRight(n).rotateRight(-n))
}
}
test(0x73, 4, 0x37)
test(0x73, -3, 0x6E)
test(0x73, 1, 0xE6.toByte())
test(0xE6.toByte(), 1, 0xCD.toByte())
repeat(100) {
testCyclic(Random.nextInt().toByte())
}
}
@Test
fun longRotate() {
fun test(value: Long, n: Int, expected: Long) {
assertEquals(expected, value.rotateLeft(n))
assertEquals(expected, value.rotateRight(-n))
}
fun testCyclic(value: Long) {
for (n in -2 * Long.SIZE_BITS..2 * Long.SIZE_BITS) {
val rl = value.rotateLeft(n)
val rr = value.rotateRight(-n)
assertEquals(rl, rr)
assertEquals(rl, value.rotateLeft(n % Long.SIZE_BITS))
assertEquals(rr, value.rotateRight((-n) % Long.SIZE_BITS))
assertEquals(value, value.rotateLeft(n).rotateLeft(-n))
assertEquals(value, value.rotateRight(n).rotateRight(-n))
}
}
test(0x7372ABAC_DEEF0123, 4, 0x372ABAC_DEEF01237)
test(0x88888888_44444444U.toLong(), -3, 0x91111111_08888888u.toLong())
test(0x88888888_44444444U.toLong(), 1, 0x11111110_88888889)
repeat(100) {
testCyclic(Random.nextLong())
}
}
@Test
fun shortRotate() {
fun test(value: Short, n: Int, expected: Short) {
assertEquals(expected, value.rotateLeft(n))
assertEquals(expected, value.rotateRight(-n))
}
fun testCyclic(value: Short) {
for (n in -2 * Short.SIZE_BITS..2 * Short.SIZE_BITS) {
val rl = value.rotateLeft(n)
val rr = value.rotateRight(-n)
assertEquals(rl, rr)
assertEquals(rl, value.rotateLeft(n % Short.SIZE_BITS))
assertEquals(rr, value.rotateRight((-n) % Short.SIZE_BITS))
assertEquals(value, value.rotateLeft(n).rotateLeft(-n))
assertEquals(value, value.rotateRight(n).rotateRight(-n))
}
}
test(0x7361, 4, 0x3617)
test(0x7361, -3, 0b001_0111_0011_0110_0)
test(0x7361, 1, 0b111_0011_0110_0001_0.toShort())
test(0xE6C2.toShort(), 1, 0b11_0011_0110_0001_01.toShort())
repeat(100) {
testCyclic(Random.nextInt().toShort())
}
}
}