1 //===-- llvm/Support/MathExtras.h - Useful math functions -------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains some functions that are useful for math stuff.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_SUPPORT_MATHEXTRAS_H
15 #define LLVM_SUPPORT_MATHEXTRAS_H
17 #include "llvm/Support/DataTypes.h"
21 // NOTE: The following support functions use the _32/_64 extensions instead of
22 // type overloading so that signed and unsigned integers can be used without
26 // Hi_32 - This function returns the high 32 bits of a 64 bit value.
27 inline unsigned Hi_32(uint64_t Value) {
28 return (unsigned)(Value >> 32);
31 // Lo_32 - This function returns the low 32 bits of a 64 bit value.
32 inline unsigned Lo_32(uint64_t Value) {
33 return (unsigned)Value;
36 // is?Type - these functions produce optimal testing for integer data types.
37 inline bool isInt8 (int Value) { return ( signed char )Value == Value; }
38 inline bool isUInt8 (int Value) { return (unsigned char )Value == Value; }
39 inline bool isInt16 (int Value) { return ( signed short)Value == Value; }
40 inline bool isUInt16(int Value) { return (unsigned short)Value == Value; }
41 inline bool isInt32 (int64_t Value) { return ( signed int )Value == Value; }
42 inline bool isUInt32(int64_t Value) { return (unsigned int )Value == Value; }
44 // isMask_32 - This function returns true if the argument is a sequence of ones
45 // starting at the least significant bit with the remainder zero (32 bit version.)
46 // Ex. isMask_32(0x0000FFFFU) == true.
47 inline const bool isMask_32(unsigned Value) {
48 return Value && ((Value + 1) & Value) == 0;
51 // isMask_64 - This function returns true if the argument is a sequence of ones
52 // starting at the least significant bit with the remainder zero (64 bit version.)
53 inline const bool isMask_64(uint64_t Value) {
54 return Value && ((Value + 1) & Value) == 0;
57 // isShiftedMask_32 - This function returns true if the argument contains a
58 // sequence of ones with the remainder zero (32 bit version.)
59 // Ex. isShiftedMask_32(0x0000FF00U) == true.
60 inline const bool isShiftedMask_32(unsigned Value) {
61 return isMask_32((Value - 1) | Value);
64 // isShiftedMask_64 - This function returns true if the argument contains a
65 // sequence of ones with the remainder zero (64 bit version.)
66 inline const bool isShiftedMask_64(uint64_t Value) {
67 return isMask_64((Value - 1) | Value);
70 // isPowerOf2_32 - This function returns true if the argument is a power of
71 // two > 0. Ex. isPowerOf2_32(0x00100000U) == true (32 bit edition.)
72 inline bool isPowerOf2_32(unsigned Value) {
73 return Value && !(Value & (Value - 1));
76 // isPowerOf2_64 - This function returns true if the argument is a power of two
77 // > 0 (64 bit edition.)
78 inline bool isPowerOf2_64(uint64_t Value) {
79 return Value && !(Value & (Value - 1LL));
82 // CountLeadingZeros_32 - this function performs the platform optimal form of
83 // counting the number of zeros from the most significant bit to the first one
84 // bit. Ex. CountLeadingZeros_32(0x00F000FF) == 8.
85 // Returns 32 if the word is zero.
86 // CountLeadingZeros_32 - this function performs the platform optimal form
87 // of counting the number of zeros from the most significant bit to the first
88 // one bit. Ex. CountLeadingZeros_32(0x00F000FF) == 8.
89 // Returns 32 if the word is zero.
90 inline unsigned CountLeadingZeros_32(unsigned Value) {
91 unsigned Count; // result
93 // PowerPC is defined for __builtin_clz(0)
94 #if !defined(__ppc__) && !defined(__ppc64__)
95 if (!Value) return 32;
97 Count = __builtin_clz(Value);
99 if (!Value) return 32;
101 // bisecton method for count leading zeros
102 for (unsigned Shift = 32 >> 1; Shift; Shift >>= 1) {
103 unsigned Tmp = Value >> Shift;
114 // CountLeadingZeros_64 - This function performs the platform optimal form
115 // of counting the number of zeros from the most significant bit to the first
116 // one bit (64 bit edition.)
117 // Returns 64 if the word is zero.
118 inline unsigned CountLeadingZeros_64(uint64_t Value) {
119 unsigned Count; // result
121 // PowerPC is defined for __builtin_clzll(0)
122 #if !defined(__ppc__) && !defined(__ppc64__)
123 if (!Value) return 64;
125 Count = __builtin_clzll(Value);
127 if (sizeof(long) == sizeof(int64_t)) {
128 if (!Value) return 64;
130 // bisecton method for count leading zeros
131 for (uint64_t Shift = 64 >> 1; Shift; Shift >>= 1) {
132 uint64_t Tmp = Value >> Shift;
141 unsigned Hi = Hi_32(Value);
143 // if some bits in hi portion
145 // leading zeros in hi portion plus all bits in lo portion
146 Count = CountLeadingZeros_32(Hi);
149 unsigned Lo = Lo_32(Value);
150 // same as 32 bit value
151 Count = CountLeadingZeros_32(Lo)+32;
158 // Log2_32 - This function returns the floor log base 2 of the specified value,
159 // -1 if the value is zero. (32 bit edition.)
160 // Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1
161 inline unsigned Log2_32(unsigned Value) {
162 return 31 - CountLeadingZeros_32(Value);
165 // Log2_64 - This function returns the floor log base 2 of the specified value,
166 // -1 if the value is zero. (64 bit edition.)
167 inline unsigned Log2_64(uint64_t Value) {
168 return 63 - CountLeadingZeros_64(Value);
171 // BitsToDouble - This function takes a 64-bit integer and returns the bit
172 // equivalent double.
173 inline double BitsToDouble(uint64_t Bits) {
182 // BitsToFloat - This function takes a 32-bit integer and returns the bit
184 inline float BitsToFloat(unsigned Bits) {
193 // DoubleToBits - This function takes a double and returns the bit
194 // equivalent 64-bit integer.
195 inline uint64_t DoubleToBits(double Double) {
204 // FloatToBits - This function takes a float and returns the bit
205 // equivalent 32-bit integer.
206 inline unsigned FloatToBits(float Float) {
215 // Platform-independent wrappers for the C99 isnan() function.
217 int IsNAN (double d);
219 // Platform-independent wrappers for the C99 isinf() function.
221 int IsInf (double d);
223 } // End llvm namespace