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 type
22 // overloading so that signed and unsigned integers can be used without ambiguity.
25 // Hi_32 - This function returns the high 32 bits of a 64 bit value.
26 inline unsigned Hi_32(uint64_t Value) {
27 return (unsigned)(Value >> 32);
30 // Lo_32 - This function returns the low 32 bits of a 64 bit value.
31 inline unsigned Lo_32(uint64_t Value) {
32 return (unsigned)Value;
35 // is?Type - these functions produce optimal testing for integer data types.
36 inline bool isInt8 (int Value) { return ( signed char )Value == Value; }
37 inline bool isUInt8 (int Value) { return (unsigned char )Value == Value; }
38 inline bool isInt16 (int Value) { return ( signed short)Value == Value; }
39 inline bool isUInt16(int Value) { return (unsigned short)Value == Value; }
40 inline bool isInt32 (int64_t Value) { return ( signed int )Value == Value; }
41 inline bool isUInt32(int64_t Value) { return (unsigned int )Value == Value; }
43 // isMask_32 - This function returns true if the argument is a sequence of ones starting
44 // at the least significant bit with the remainder zero (32 bit version.)
45 // Ex. isMask_32(0x0000FFFFU) == true.
46 inline const bool isMask_32(unsigned Value) {
47 return Value && ((Value + 1) & Value) == 0;
50 // isMask_64 - This function returns true if the argument is a sequence of ones starting
51 // at the least significant bit with the remainder zero (64 bit version.)
52 inline const bool isMask_64(uint64_t Value) {
53 return Value && ((Value + 1) & Value) == 0;
56 // isShiftedMask_32 - This function returns true if the argument contains a sequence of ones
57 // with the remainder zero (32 bit version.)
58 // Ex. isShiftedMask_32(0x0000FF00U) == true.
59 inline const bool isShiftedMask_32(unsigned Value) {
60 return isMask_32((Value - 1) | Value);
63 // isShiftedMask_64 - This function returns true if the argument contains a sequence of ones
64 // with the remainder zero (64 bit version.)
65 inline const bool isShiftedMask_64(uint64_t Value) {
66 return isMask_64((Value - 1) | Value);
69 // isPowerOf2_32 - This function returns true if the argument is a power of two > 0.
70 // Ex. isPowerOf2_32(0x00100000U) == true (32 bit edition.)
71 inline bool isPowerOf2_32(unsigned Value) {
72 return Value && !(Value & (Value - 1));
75 // isPowerOf2_64 - This function returns true if the argument is a power of two > 0
77 inline bool isPowerOf2_64(uint64_t Value) {
78 return Value && !(Value & (Value - 1LL));
81 // CountLeadingZeros_32 - this function performs the platform optimal form
82 // of counting the number of zeros from the most significant bit to the first one bit.
83 // Ex. CountLeadingZeros_32(0x00F000FF) == 8.
84 // Returns 32 if the word is zero.
85 inline unsigned CountLeadingZeros_32(unsigned Value) {
86 unsigned Count; // result
88 // PowerPC is defined for __builtin_clz(0)
89 #if !defined(__ppc__) && !defined(__ppc64__)
90 if (!Value) return 32;
92 Count = __builtin_clz(Value);
94 if (!Value) return 32;
96 // bisecton method for count leading zeros
97 for (unsigned Shift = 32 >> 1; Shift; Shift >>= 1) {
98 unsigned Tmp = Value >> Shift;
108 // CountLeadingZeros_64 - This function performs the platform optimal form
109 // of counting the number of zeros from the most significant bit to the first one bit
111 // Returns 64 if the word is zero.
112 inline unsigned CountLeadingZeros_64(uint64_t Value) {
113 unsigned Count; // result
115 // PowerPC is defined for __builtin_clzll(0)
116 #if !defined(__ppc__) && !defined(__ppc64__)
117 if (!Value) return 64;
119 Count = __builtin_clzll(Value);
121 if (sizeof(long) == sizeof(int64_t)) {
122 if (!Value) return 64;
124 // bisecton method for count leading zeros
125 for (uint64_t Shift = 64 >> 1; Shift; Shift >>= 1) {
126 uint64_t Tmp = Value >> Shift;
134 unsigned Hi = Hi_32(Value);
136 // if some bits in hi portion
138 // leading zeros in hi portion plus all bits in lo portion
139 Count = CountLeadingZeros_32(Hi) + 32;
142 unsigned Lo = Lo_32(Value);
143 // same as 32 bit value
144 Count = CountLeadingZeros_32(Lo);
151 // Log2_32 - This function returns the floor log base 2 of the specified value, -1 if the value is zero.
153 // Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1
154 inline unsigned Log2_32(unsigned Value) {
155 return 31 - CountLeadingZeros_32(Value);
158 // Log2_64 - This function returns the floor log base 2 of the specified value, -1 if the value is zero.
160 inline unsigned Log2_64(unsigned Value) {
161 return 63 - CountLeadingZeros_64(Value);
164 // Platform-independent wrappers for the C99 isnan() function.
166 int IsNAN (double d);
168 // Platform-independent wrappers for the C99 isinf() function.
170 int IsInf (double d);
172 } // End llvm namespace