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Actual implementations for bit functions

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This commit is contained in:
Ilya Gorbunov
2019-06-21 05:16:17 +03:00
parent 0146589725
commit ff4c932e67
2 changed files with 151 additions and 3 deletions
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runtime/src/main/kotlin/kotlin/Numbers.kt
+151
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@@ -101,3 +101,154 @@ public actual inline fun Float.Companion.fromBits(bits: Int): Float = kotlin.fro
@PublishedApi
@TypedIntrinsic(IntrinsicType.REINTERPRET)
internal external fun fromBits(bits: Int): Float
/**
* Counts the number of set bits in the binary representation of this [Int] number.
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Int.countOneBits(): Int {
var v = this
v = (v and 0x55555555) + (v.ushr(1) and 0x55555555)
v = (v and 0x33333333) + (v.ushr(2) and 0x33333333)
v = (v and 0x0F0F0F0F) + (v.ushr(4) and 0x0F0F0F0F)
v = (v and 0x00FF00FF) + (v.ushr(8) and 0x00FF00FF)
v = (v and 0x0000FFFF) + (v.ushr(16))
return v
}
/**
* Counts the number of consecutive most significant bits that are zero in the binary representation of this [Int] number.
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Int.countLeadingZeroBits(): Int = TODO()
/**
* Counts the number of consecutive least significant bits that are zero in the binary representation of this [Int] number.
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Int.countTrailingZeroBits(): Int = TODO()
// Int.SIZE_BITS - (this or -this).inv().countLeadingZeroBits()
/**
* Returns a number having a single bit set in the position of the most significant set bit of this [Int] number,
* or zero, if this number is zero.
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Int.takeHighestOneBit(): Int =
if (this == 0) 0 else 1.shl(Int.SIZE_BITS - 1 - countLeadingZeroBits())
/**
* Returns a number having a single bit set in the position of the least significant set bit of this [Int] number,
* or zero, if this number is zero.
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Int.takeLowestOneBit(): Int =
this and -this
/**
* Rotates the binary representation of this [Int] number left by the specified [bitCount] number of bits.
* The most significant bits pushed out from the left side reenter the number as the least significant bits on the right side.
*
* Rotating the number left by a negative bit count is the same as rotating it right by the negated bit count:
* `number.rotateLeft(-n) == number.rotateRight(n)`
*
* Rotating by a multiple of [Int.SIZE_BITS] (32) returns the same number, or more generally
* `number.rotateLeft(n) == number.rotateLeft(n % 32)`
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Int.rotateLeft(bitCount: Int): Int =
shl(bitCount) or ushr(Int.SIZE_BITS - bitCount)
/**
* Rotates the binary representation of this [Int] number right by the specified [bitCount] number of bits.
* The least significant bits pushed out from the right side reenter the number as the most significant bits on the left side.
*
* Rotating the number right by a negative bit count is the same as rotating it left by the negated bit count:
* `number.rotateRight(-n) == number.rotateLeft(n)`
*
* Rotating by a multiple of [Int.SIZE_BITS] (32) returns the same number, or more generally
* `number.rotateRight(n) == number.rotateRight(n % 32)`
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Int.rotateRight(bitCount: Int): Int =
shl(Int.SIZE_BITS - bitCount) or ushr(bitCount)
/**
* Counts the number of set bits in the binary representation of this [Long] number.
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Long.countOneBits(): Int = TODO()
// high.countOneBits() + low.countOneBits()
/**
* Counts the number of consecutive most significant bits that are zero in the binary representation of this [Long] number.
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Long.countLeadingZeroBits(): Int = TODO()
/**
* Counts the number of consecutive least significant bits that are zero in the binary representation of this [Long] number.
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Long.countTrailingZeroBits(): Int = TODO()
/**
* Returns a number having a single bit set in the position of the most significant set bit of this [Long] number,
* or zero, if this number is zero.
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Long.takeHighestOneBit(): Long = TODO()
/**
* Returns a number having a single bit set in the position of the least significant set bit of this [Long] number,
* or zero, if this number is zero.
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Long.takeLowestOneBit(): Long =
this and -this
/**
* Rotates the binary representation of this [Long] number left by the specified [bitCount] number of bits.
* The most significant bits pushed out from the left side reenter the number as the least significant bits on the right side.
*
* Rotating the number left by a negative bit count is the same as rotating it right by the negated bit count:
* `number.rotateLeft(-n) == number.rotateRight(n)`
*
* Rotating by a multiple of [Long.SIZE_BITS] (64) returns the same number, or more generally
* `number.rotateLeft(n) == number.rotateLeft(n % 64)`
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
public actual fun Long.rotateLeft(bitCount: Int): Long =
shl(bitCount) or ushr(Long.SIZE_BITS - bitCount)
/**
* Rotates the binary representation of this [Long] number right by the specified [bitCount] number of bits.
* The least significant bits pushed out from the right side reenter the number as the most significant bits on the left side.
*
* Rotating the number right by a negative bit count is the same as rotating it left by the negated bit count:
* `number.rotateRight(-n) == number.rotateLeft(n)`
*
* Rotating by a multiple of [Long.SIZE_BITS] (64) returns the same number, or more generally
* `number.rotateRight(n) == number.rotateRight(n % 64)`
*/
@SinceKotlin("1.3")
@ExperimentalStdlibApi
@kotlin.internal.InlineOnly
public actual inline fun Long.rotateRight(bitCount: Int): Long =
shl(Long.SIZE_BITS - bitCount) or ushr(bitCount)
runtime/src/main/kotlin/kotlin/random/Random.kt
-3
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@@ -36,8 +36,5 @@ internal object NativeRandom : Random() {
internal actual fun defaultPlatformRandom(): Random = NativeRandom
internal actual fun fastLog2(value: Int): Int =
31 - value.numberOfLeadingZeros()
internal actual fun doubleFromParts(hi26: Int, low27: Int): Double =
(hi26.toLong().shl(27) + low27) / (1L shl 53).toDouble()