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 // ByteSwap_16 - This function returns a byte-swapped representation of the
83 // 16-bit argument, Value.
84 inline unsigned short ByteSwap_16(unsigned short Value) {
85 unsigned short Hi = Value << 8;
86 unsigned short Lo = Value >> 8;
90 // ByteSwap_32 - This function returns a byte-swapped representation of the
91 // 32-bit argument, Value.
92 inline unsigned ByteSwap_32(unsigned Value) {
93 unsigned Byte0 = Value & 0x000000FF;
94 unsigned Byte1 = Value & 0x0000FF00;
95 unsigned Byte2 = Value & 0x00FF0000;
96 unsigned Byte3 = Value & 0xFF000000;
97 return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24);
100 // ByteSwap_64 - This function returns a byte-swapped representation of the
101 // 64-bit argument, Value.
102 inline uint64_t ByteSwap_64(uint64_t Value) {
103 uint64_t Hi = ByteSwap_32(Value);
104 uint64_t Lo = ByteSwap_32(Value >> 32);
105 return (Hi << 32) | Lo;
108 // CountLeadingZeros_32 - this function performs the platform optimal form of
109 // counting the number of zeros from the most significant bit to the first one
110 // bit. Ex. CountLeadingZeros_32(0x00F000FF) == 8.
111 // Returns 32 if the word is zero.
112 inline unsigned CountLeadingZeros_32(unsigned Value) {
113 unsigned Count; // result
115 // PowerPC is defined for __builtin_clz(0)
116 #if !defined(__ppc__) && !defined(__ppc64__)
117 if (!Value) return 32;
119 Count = __builtin_clz(Value);
121 if (!Value) return 32;
123 // bisecton method for count leading zeros
124 for (unsigned Shift = 32 >> 1; Shift; Shift >>= 1) {
125 unsigned Tmp = Value >> Shift;
136 // CountLeadingZeros_64 - This function performs the platform optimal form
137 // of counting the number of zeros from the most significant bit to the first
138 // one bit (64 bit edition.)
139 // Returns 64 if the word is zero.
140 inline unsigned CountLeadingZeros_64(uint64_t Value) {
141 unsigned Count; // result
143 // PowerPC is defined for __builtin_clzll(0)
144 #if !defined(__ppc__) && !defined(__ppc64__)
145 if (!Value) return 64;
147 Count = __builtin_clzll(Value);
149 if (sizeof(long) == sizeof(int64_t)) {
150 if (!Value) return 64;
152 // bisecton method for count leading zeros
153 for (uint64_t Shift = 64 >> 1; Shift; Shift >>= 1) {
154 uint64_t Tmp = Value >> Shift;
163 unsigned Hi = Hi_32(Value);
165 // if some bits in hi portion
167 // leading zeros in hi portion plus all bits in lo portion
168 Count = CountLeadingZeros_32(Hi);
171 unsigned Lo = Lo_32(Value);
172 // same as 32 bit value
173 Count = CountLeadingZeros_32(Lo)+32;
180 // CountTrailingZeros_32 - this function performs the platform optimal form of
181 // counting the number of zeros from the least significant bit to the first one
182 // bit. Ex. CountTrailingZeros_32(0xFF00FF00) == 8.
183 // Returns 32 if the word is zero.
184 inline unsigned CountTrailingZeros_32(unsigned Value) {
185 return 32 - CountLeadingZeros_32(~Value & (Value - 1));
188 // CountTrailingZeros_64 - This function performs the platform optimal form
189 // of counting the number of zeros from the least significant bit to the first
190 // one bit (64 bit edition.)
191 // Returns 64 if the word is zero.
192 inline unsigned CountTrailingZeros_64(uint64_t Value) {
193 return 64 - CountLeadingZeros_64(~Value & (Value - 1));
196 // CountPopulation_32 - this function counts the number of set bits in a value.
197 // Ex. CountPopulation(0xF000F000) = 8
198 // Returns 0 if the word is zero.
199 inline unsigned CountPopulation_32(unsigned Value) {
201 x = Value - ((Value >> 1) & 0x55555555);
202 t = ((x >> 2) & 0x33333333);
203 x = (x & 0x33333333) + t;
204 x = (x + (x >> 4)) & 0x0F0F0F0F;
210 // CountPopulation_64 - this function counts the number of set bits in a value,
212 inline unsigned CountPopulation_64(uint64_t Value) {
213 return CountPopulation_32(unsigned(Value >> 32)) +
214 CountPopulation_32(unsigned(Value));
217 // Log2_32 - This function returns the floor log base 2 of the specified value,
218 // -1 if the value is zero. (32 bit edition.)
219 // Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1
220 inline unsigned Log2_32(unsigned Value) {
221 return 31 - CountLeadingZeros_32(Value);
224 // Log2_64 - This function returns the floor log base 2 of the specified value,
225 // -1 if the value is zero. (64 bit edition.)
226 inline unsigned Log2_64(uint64_t Value) {
227 return 63 - CountLeadingZeros_64(Value);
230 // BitsToDouble - This function takes a 64-bit integer and returns the bit
231 // equivalent double.
232 inline double BitsToDouble(uint64_t Bits) {
241 // BitsToFloat - This function takes a 32-bit integer and returns the bit
243 inline float BitsToFloat(uint32_t Bits) {
252 // DoubleToBits - This function takes a double and returns the bit
253 // equivalent 64-bit integer.
254 inline uint64_t DoubleToBits(double Double) {
263 // FloatToBits - This function takes a float and returns the bit
264 // equivalent 32-bit integer.
265 inline uint32_t FloatToBits(float Float) {
274 // Platform-independent wrappers for the C99 isnan() function.
276 int IsNAN (double d);
278 // Platform-independent wrappers for the C99 isinf() function.
280 int IsInf (double d);
282 } // End llvm namespace