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 static_cast<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 static_cast<unsigned>(Value);
36 // is?Type - these functions produce optimal testing for integer data types.
37 inline bool isInt8 (int Value) {
38 return static_cast<signed char>(Value) == Value;
40 inline bool isUInt8 (int Value) {
41 return static_cast<unsigned char>(Value) == Value;
43 inline bool isInt16 (int Value) {
44 return static_cast<signed short>(Value) == Value;
46 inline bool isUInt16(int Value) {
47 return static_cast<unsigned short>(Value) == Value;
49 inline bool isInt32 (int64_t Value) {
50 return static_cast<signed int>(Value) == Value;
52 inline bool isUInt32(int64_t Value) {
53 return static_cast<unsigned int>(Value) == Value;
56 // isMask_32 - This function returns true if the argument is a sequence of ones
57 // starting at the least significant bit with the remainder zero (32 bit version.)
58 // Ex. isMask_32(0x0000FFFFU) == true.
59 inline const bool isMask_32(unsigned Value) {
60 return Value && ((Value + 1) & Value) == 0;
63 // isMask_64 - This function returns true if the argument is a sequence of ones
64 // starting at the least significant bit with the remainder zero (64 bit version.)
65 inline const bool isMask_64(uint64_t Value) {
66 return Value && ((Value + 1) & Value) == 0;
69 // isShiftedMask_32 - This function returns true if the argument contains a
70 // sequence of ones with the remainder zero (32 bit version.)
71 // Ex. isShiftedMask_32(0x0000FF00U) == true.
72 inline const bool isShiftedMask_32(unsigned Value) {
73 return isMask_32((Value - 1) | Value);
76 // isShiftedMask_64 - This function returns true if the argument contains a
77 // sequence of ones with the remainder zero (64 bit version.)
78 inline const bool isShiftedMask_64(uint64_t Value) {
79 return isMask_64((Value - 1) | Value);
82 // isPowerOf2_32 - This function returns true if the argument is a power of
83 // two > 0. Ex. isPowerOf2_32(0x00100000U) == true (32 bit edition.)
84 inline bool isPowerOf2_32(unsigned Value) {
85 return Value && !(Value & (Value - 1));
88 // isPowerOf2_64 - This function returns true if the argument is a power of two
89 // > 0 (64 bit edition.)
90 inline bool isPowerOf2_64(uint64_t Value) {
91 return Value && !(Value & (Value - int64_t(1L)));
94 // ByteSwap_16 - This function returns a byte-swapped representation of the
95 // 16-bit argument, Value.
96 inline unsigned short ByteSwap_16(unsigned short Value) {
97 unsigned short Hi = Value << 8;
98 unsigned short Lo = Value >> 8;
102 // ByteSwap_32 - This function returns a byte-swapped representation of the
103 // 32-bit argument, Value.
104 inline unsigned ByteSwap_32(unsigned Value) {
105 unsigned Byte0 = Value & 0x000000FF;
106 unsigned Byte1 = Value & 0x0000FF00;
107 unsigned Byte2 = Value & 0x00FF0000;
108 unsigned Byte3 = Value & 0xFF000000;
109 return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24);
112 // ByteSwap_64 - This function returns a byte-swapped representation of the
113 // 64-bit argument, Value.
114 inline uint64_t ByteSwap_64(uint64_t Value) {
115 uint64_t Hi = ByteSwap_32(unsigned(Value));
116 uint64_t Lo = ByteSwap_32(unsigned(Value >> 32));
117 return (Hi << 32) | Lo;
120 // CountLeadingZeros_32 - this function performs the platform optimal form of
121 // counting the number of zeros from the most significant bit to the first one
122 // bit. Ex. CountLeadingZeros_32(0x00F000FF) == 8.
123 // Returns 32 if the word is zero.
124 inline unsigned CountLeadingZeros_32(unsigned Value) {
125 unsigned Count; // result
127 // PowerPC is defined for __builtin_clz(0)
128 #if !defined(__ppc__) && !defined(__ppc64__)
129 if (!Value) return 32;
131 Count = __builtin_clz(Value);
133 if (!Value) return 32;
135 // bisecton method for count leading zeros
136 for (unsigned Shift = 32 >> 1; Shift; Shift >>= 1) {
137 unsigned Tmp = Value >> Shift;
148 // CountLeadingZeros_64 - This function performs the platform optimal form
149 // of counting the number of zeros from the most significant bit to the first
150 // one bit (64 bit edition.)
151 // Returns 64 if the word is zero.
152 inline unsigned CountLeadingZeros_64(uint64_t Value) {
153 unsigned Count; // result
155 // PowerPC is defined for __builtin_clzll(0)
156 #if !defined(__ppc__) && !defined(__ppc64__)
157 if (!Value) return 64;
159 Count = __builtin_clzll(Value);
161 if (sizeof(long) == sizeof(int64_t)) {
162 if (!Value) return 64;
164 // bisecton method for count leading zeros
165 for (uint64_t Shift = 64 >> 1; Shift; Shift >>= 1) {
166 uint64_t Tmp = Value >> Shift;
175 unsigned Hi = Hi_32(Value);
177 // if some bits in hi portion
179 // leading zeros in hi portion plus all bits in lo portion
180 Count = CountLeadingZeros_32(Hi);
183 unsigned Lo = Lo_32(Value);
184 // same as 32 bit value
185 Count = CountLeadingZeros_32(Lo)+32;
192 // CountTrailingZeros_32 - this function performs the platform optimal form of
193 // counting the number of zeros from the least significant bit to the first one
194 // bit. Ex. CountTrailingZeros_32(0xFF00FF00) == 8.
195 // Returns 32 if the word is zero.
196 inline unsigned CountTrailingZeros_32(unsigned Value) {
197 return 32 - CountLeadingZeros_32(~Value & (Value - 1));
200 // CountTrailingZeros_64 - This function performs the platform optimal form
201 // of counting the number of zeros from the least significant bit to the first
202 // one bit (64 bit edition.)
203 // Returns 64 if the word is zero.
204 inline unsigned CountTrailingZeros_64(uint64_t Value) {
205 return 64 - CountLeadingZeros_64(~Value & (Value - 1));
208 // CountPopulation_32 - this function counts the number of set bits in a value.
209 // Ex. CountPopulation(0xF000F000) = 8
210 // Returns 0 if the word is zero.
211 inline unsigned CountPopulation_32(unsigned Value) {
213 x = Value - ((Value >> 1) & 0x55555555);
214 t = ((x >> 2) & 0x33333333);
215 x = (x & 0x33333333) + t;
216 x = (x + (x >> 4)) & 0x0F0F0F0F;
222 // CountPopulation_64 - this function counts the number of set bits in a value,
224 inline unsigned CountPopulation_64(uint64_t Value) {
225 return CountPopulation_32(unsigned(Value >> 32)) +
226 CountPopulation_32(unsigned(Value));
229 // Log2_32 - This function returns the floor log base 2 of the specified value,
230 // -1 if the value is zero. (32 bit edition.)
231 // Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1
232 inline unsigned Log2_32(unsigned Value) {
233 return 31 - CountLeadingZeros_32(Value);
236 // Log2_64 - This function returns the floor log base 2 of the specified value,
237 // -1 if the value is zero. (64 bit edition.)
238 inline unsigned Log2_64(uint64_t Value) {
239 return 63 - CountLeadingZeros_64(Value);
242 // BitsToDouble - This function takes a 64-bit integer and returns the bit
243 // equivalent double.
244 inline double BitsToDouble(uint64_t Bits) {
253 // BitsToFloat - This function takes a 32-bit integer and returns the bit
255 inline float BitsToFloat(uint32_t Bits) {
264 // DoubleToBits - This function takes a double and returns the bit
265 // equivalent 64-bit integer.
266 inline uint64_t DoubleToBits(double Double) {
275 // FloatToBits - This function takes a float and returns the bit
276 // equivalent 32-bit integer.
277 inline uint32_t FloatToBits(float Float) {
286 // Platform-independent wrappers for the C99 isnan() function.
288 int IsNAN (double d);
290 // Platform-independent wrappers for the C99 isinf() function.
292 int IsInf (double d);
294 } // End llvm namespace