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
76 // > 0 (64 bit edition.)
77 inline bool isPowerOf2_64(uint64_t Value) {
78 return Value && !(Value & (Value - 1LL));
81 // CountLeadingZeros_32 - this function performs the platform optimal form of
82 // counting the number of zeros from the most significant bit to the first one
83 // bit. Ex. CountLeadingZeros_32(0x00F000FF) == 8.
84 // Returns 32 if the word is zero.
85 // CountLeadingZeros_32 - this function performs the platform optimal form
86 // of counting the number of zeros from the most significant bit to the first
87 // one bit. Ex. CountLeadingZeros_32(0x00F000FF) == 8.
88 // Returns 32 if the word is zero.
89 inline unsigned CountLeadingZeros_32(unsigned Value) {
90 unsigned Count; // result
92 // PowerPC is defined for __builtin_clz(0)
93 #if !defined(__ppc__) && !defined(__ppc64__)
94 if (!Value) return 32;
96 Count = __builtin_clz(Value);
98 if (!Value) return 32;
100 // bisecton method for count leading zeros
101 for (unsigned Shift = 32 >> 1; Shift; Shift >>= 1) {
102 unsigned Tmp = Value >> Shift;
113 // CountLeadingZeros_64 - This function performs the platform optimal form
114 // of counting the number of zeros from the most significant bit to the first one bit
116 // Returns 64 if the word is zero.
117 inline unsigned CountLeadingZeros_64(uint64_t Value) {
118 unsigned Count; // result
120 // PowerPC is defined for __builtin_clzll(0)
121 #if defined(__ppc__) || defined(__ppc64__)
122 if (!Value) return 64;
124 Count = __builtin_clzll(Value);
126 if (sizeof(long) == sizeof(int64_t)) {
127 if (!Value) return 64;
129 // bisecton method for count leading zeros
130 for (uint64_t Shift = 64 >> 1; Shift; Shift >>= 1) {
131 uint64_t Tmp = Value >> Shift;
140 unsigned Hi = Hi_32(Value);
142 // if some bits in hi portion
144 // leading zeros in hi portion plus all bits in lo portion
145 Count = CountLeadingZeros_32(Hi) + 32;
148 unsigned Lo = Lo_32(Value);
149 // same as 32 bit value
150 Count = CountLeadingZeros_32(Lo);
157 // Log2_32 - This function returns the floor log base 2 of the specified value, -1 if the value is zero.
159 // Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1
160 inline unsigned Log2_32(unsigned Value) {
161 return 31 - CountLeadingZeros_32(Value);
164 // Log2_64 - This function returns the floor log base 2 of the specified value, -1 if the value is zero.
166 inline unsigned Log2_64(unsigned Value) {
167 return 63 - CountLeadingZeros_64(Value);
170 // Platform-independent wrappers for the C99 isnan() function.
172 int IsNAN (double d);
174 // Platform-independent wrappers for the C99 isinf() function.
176 int IsInf (double d);
178 } // End llvm namespace