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#includes it. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@29639 91177308-0d34-0410-b5e6-96231b3b80d8
311 lines
9.5 KiB
C++
311 lines
9.5 KiB
C++
//===-- llvm/Support/MathExtras.h - Useful math functions -------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains some functions that are useful for math stuff.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_MATHEXTRAS_H
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#define LLVM_SUPPORT_MATHEXTRAS_H
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#include "llvm/Support/DataTypes.h"
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#include "llvm/System/IncludeFile.h"
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namespace llvm {
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// NOTE: The following support functions use the _32/_64 extensions instead of
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// type overloading so that signed and unsigned integers can be used without
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// ambiguity.
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// Hi_32 - This function returns the high 32 bits of a 64 bit value.
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inline unsigned Hi_32(uint64_t Value) {
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return static_cast<unsigned>(Value >> 32);
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}
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// Lo_32 - This function returns the low 32 bits of a 64 bit value.
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inline unsigned Lo_32(uint64_t Value) {
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return static_cast<unsigned>(Value);
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}
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// is?Type - these functions produce optimal testing for integer data types.
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inline bool isInt8 (int Value) {
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return static_cast<signed char>(Value) == Value;
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}
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inline bool isUInt8 (int Value) {
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return static_cast<unsigned char>(Value) == Value;
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}
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inline bool isInt16 (int Value) {
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return static_cast<signed short>(Value) == Value;
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}
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inline bool isUInt16(int Value) {
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return static_cast<unsigned short>(Value) == Value;
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}
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inline bool isInt32 (int64_t Value) {
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return static_cast<signed int>(Value) == Value;
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}
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inline bool isUInt32(int64_t Value) {
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return static_cast<unsigned int>(Value) == Value;
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}
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// isMask_32 - This function returns true if the argument is a sequence of ones
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// starting at the least significant bit with the remainder zero (32 bit version.)
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// Ex. isMask_32(0x0000FFFFU) == true.
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inline const bool isMask_32(unsigned Value) {
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return Value && ((Value + 1) & Value) == 0;
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}
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// isMask_64 - This function returns true if the argument is a sequence of ones
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// starting at the least significant bit with the remainder zero (64 bit version.)
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inline const bool isMask_64(uint64_t Value) {
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return Value && ((Value + 1) & Value) == 0;
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}
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// isShiftedMask_32 - This function returns true if the argument contains a
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// sequence of ones with the remainder zero (32 bit version.)
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// Ex. isShiftedMask_32(0x0000FF00U) == true.
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inline const bool isShiftedMask_32(unsigned Value) {
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return isMask_32((Value - 1) | Value);
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}
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// isShiftedMask_64 - This function returns true if the argument contains a
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// sequence of ones with the remainder zero (64 bit version.)
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inline const bool isShiftedMask_64(uint64_t Value) {
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return isMask_64((Value - 1) | Value);
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}
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// isPowerOf2_32 - This function returns true if the argument is a power of
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// two > 0. Ex. isPowerOf2_32(0x00100000U) == true (32 bit edition.)
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inline bool isPowerOf2_32(unsigned Value) {
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return Value && !(Value & (Value - 1));
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}
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// isPowerOf2_64 - This function returns true if the argument is a power of two
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// > 0 (64 bit edition.)
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inline bool isPowerOf2_64(uint64_t Value) {
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return Value && !(Value & (Value - int64_t(1L)));
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}
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// ByteSwap_16 - This function returns a byte-swapped representation of the
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// 16-bit argument, Value.
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inline unsigned short ByteSwap_16(unsigned short Value) {
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unsigned short Hi = Value << 8;
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unsigned short Lo = Value >> 8;
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return Hi | Lo;
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}
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// ByteSwap_32 - This function returns a byte-swapped representation of the
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// 32-bit argument, Value.
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inline unsigned ByteSwap_32(unsigned Value) {
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unsigned Byte0 = Value & 0x000000FF;
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unsigned Byte1 = Value & 0x0000FF00;
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unsigned Byte2 = Value & 0x00FF0000;
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unsigned Byte3 = Value & 0xFF000000;
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return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24);
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}
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// ByteSwap_64 - This function returns a byte-swapped representation of the
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// 64-bit argument, Value.
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inline uint64_t ByteSwap_64(uint64_t Value) {
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uint64_t Hi = ByteSwap_32(unsigned(Value));
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uint64_t Lo = ByteSwap_32(unsigned(Value >> 32));
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return (Hi << 32) | Lo;
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}
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// CountLeadingZeros_32 - this function performs the platform optimal form of
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// counting the number of zeros from the most significant bit to the first one
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// bit. Ex. CountLeadingZeros_32(0x00F000FF) == 8.
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// Returns 32 if the word is zero.
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inline unsigned CountLeadingZeros_32(unsigned Value) {
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unsigned Count; // result
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#if __GNUC__ >= 4
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// PowerPC is defined for __builtin_clz(0)
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#if !defined(__ppc__) && !defined(__ppc64__)
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if (!Value) return 32;
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#endif
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Count = __builtin_clz(Value);
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#else
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if (!Value) return 32;
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Count = 0;
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// bisecton method for count leading zeros
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for (unsigned Shift = 32 >> 1; Shift; Shift >>= 1) {
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unsigned Tmp = Value >> Shift;
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if (Tmp) {
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Value = Tmp;
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} else {
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Count |= Shift;
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}
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}
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#endif
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return Count;
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}
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// CountLeadingZeros_64 - This function performs the platform optimal form
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// of counting the number of zeros from the most significant bit to the first
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// one bit (64 bit edition.)
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// Returns 64 if the word is zero.
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inline unsigned CountLeadingZeros_64(uint64_t Value) {
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unsigned Count; // result
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#if __GNUC__ >= 4
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// PowerPC is defined for __builtin_clzll(0)
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#if !defined(__ppc__) && !defined(__ppc64__)
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if (!Value) return 64;
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#endif
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Count = __builtin_clzll(Value);
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#else
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if (sizeof(long) == sizeof(int64_t)) {
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if (!Value) return 64;
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Count = 0;
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// bisecton method for count leading zeros
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for (uint64_t Shift = 64 >> 1; Shift; Shift >>= 1) {
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uint64_t Tmp = Value >> Shift;
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if (Tmp) {
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Value = Tmp;
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} else {
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Count |= Shift;
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}
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}
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} else {
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// get hi portion
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unsigned Hi = Hi_32(Value);
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// if some bits in hi portion
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if (Hi) {
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// leading zeros in hi portion plus all bits in lo portion
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Count = CountLeadingZeros_32(Hi);
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} else {
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// get lo portion
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unsigned Lo = Lo_32(Value);
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// same as 32 bit value
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Count = CountLeadingZeros_32(Lo)+32;
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}
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}
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#endif
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return Count;
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}
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// CountTrailingZeros_32 - this function performs the platform optimal form of
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// counting the number of zeros from the least significant bit to the first one
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// bit. Ex. CountTrailingZeros_32(0xFF00FF00) == 8.
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// Returns 32 if the word is zero.
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inline unsigned CountTrailingZeros_32(unsigned Value) {
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return 32 - CountLeadingZeros_32(~Value & (Value - 1));
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}
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// CountTrailingZeros_64 - This function performs the platform optimal form
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// of counting the number of zeros from the least significant bit to the first
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// one bit (64 bit edition.)
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// Returns 64 if the word is zero.
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inline unsigned CountTrailingZeros_64(uint64_t Value) {
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return 64 - CountLeadingZeros_64(~Value & (Value - 1));
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}
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// CountPopulation_32 - this function counts the number of set bits in a value.
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// Ex. CountPopulation(0xF000F000) = 8
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// Returns 0 if the word is zero.
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inline unsigned CountPopulation_32(unsigned Value) {
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unsigned x, t;
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x = Value - ((Value >> 1) & 0x55555555);
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t = ((x >> 2) & 0x33333333);
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x = (x & 0x33333333) + t;
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x = (x + (x >> 4)) & 0x0F0F0F0F;
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x = x + (x << 8);
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x = x + (x << 16);
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return x >> 24;
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}
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// CountPopulation_64 - this function counts the number of set bits in a value,
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// (64 bit edition.)
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inline unsigned CountPopulation_64(uint64_t Value) {
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return CountPopulation_32(unsigned(Value >> 32)) +
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CountPopulation_32(unsigned(Value));
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}
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// Log2_32 - This function returns the floor log base 2 of the specified value,
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// -1 if the value is zero. (32 bit edition.)
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// Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1, Log2_32(6) == 2
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inline unsigned Log2_32(unsigned Value) {
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return 31 - CountLeadingZeros_32(Value);
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}
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// Log2_64 - This function returns the floor log base 2 of the specified value,
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// -1 if the value is zero. (64 bit edition.)
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inline unsigned Log2_64(uint64_t Value) {
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return 63 - CountLeadingZeros_64(Value);
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}
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// Log2_32_Ceil - This function returns the ceil log base 2 of the specified
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// value, 32 if the value is zero. (32 bit edition).
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// Ex. Log2_32_Ceil(32) == 5, Log2_32_Ceil(1) == 0, Log2_32_Ceil(6) == 3
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inline unsigned Log2_32_Ceil(unsigned Value) {
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return 32-CountLeadingZeros_32(Value-1);
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}
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// Log2_64 - This function returns the ceil log base 2 of the specified value,
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// 64 if the value is zero. (64 bit edition.)
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inline unsigned Log2_64_Ceil(uint64_t Value) {
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return 64-CountLeadingZeros_64(Value-1);
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}
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// BitsToDouble - This function takes a 64-bit integer and returns the bit
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// equivalent double.
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inline double BitsToDouble(uint64_t Bits) {
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union {
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uint64_t L;
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double D;
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} T;
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T.L = Bits;
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return T.D;
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}
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// BitsToFloat - This function takes a 32-bit integer and returns the bit
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// equivalent float.
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inline float BitsToFloat(uint32_t Bits) {
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union {
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uint32_t I;
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float F;
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} T;
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T.I = Bits;
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return T.F;
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}
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// DoubleToBits - This function takes a double and returns the bit
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// equivalent 64-bit integer.
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inline uint64_t DoubleToBits(double Double) {
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union {
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uint64_t L;
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double D;
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} T;
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T.D = Double;
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return T.L;
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}
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// FloatToBits - This function takes a float and returns the bit
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// equivalent 32-bit integer.
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inline uint32_t FloatToBits(float Float) {
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union {
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uint32_t I;
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float F;
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} T;
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T.F = Float;
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return T.I;
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}
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// Platform-independent wrappers for the C99 isnan() function.
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int IsNAN (float f);
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int IsNAN (double d);
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// Platform-independent wrappers for the C99 isinf() function.
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int IsInf (float f);
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int IsInf (double d);
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} // End llvm namespace
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#endif
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