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
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 static_cast<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 static_cast<unsigned>(Value);
35 /// is?Type - these functions produce optimal testing for integer data types.
36 inline bool isInt8 (int64_t Value) {
37 return static_cast<signed char>(Value) == Value;
39 inline bool isUInt8 (int64_t Value) {
40 return static_cast<unsigned char>(Value) == Value;
42 inline bool isInt16 (int64_t Value) {
43 return static_cast<signed short>(Value) == Value;
45 inline bool isUInt16(int64_t Value) {
46 return static_cast<unsigned short>(Value) == Value;
48 inline bool isInt32 (int64_t Value) {
49 return static_cast<signed int>(Value) == Value;
51 inline bool isUInt32(int64_t Value) {
52 return static_cast<unsigned int>(Value) == Value;
55 /// isMask_32 - This function returns true if the argument is a sequence of ones
56 /// starting at the least significant bit with the remainder zero (32 bit
57 /// version). Ex. isMask_32(0x0000FFFFU) == true.
58 inline const bool isMask_32(unsigned Value) {
59 return Value && ((Value + 1) & Value) == 0;
62 /// isMask_64 - This function returns true if the argument is a sequence of ones
63 /// starting at the least significant bit with the remainder zero (64 bit
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,
223 /// (64 bit edition.)
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, Log2_32(6) == 2
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 /// Log2_32_Ceil - This function returns the ceil log base 2 of the specified
243 /// value, 32 if the value is zero. (32 bit edition).
244 /// Ex. Log2_32_Ceil(32) == 5, Log2_32_Ceil(1) == 0, Log2_32_Ceil(6) == 3
245 inline unsigned Log2_32_Ceil(unsigned Value) {
246 return 32-CountLeadingZeros_32(Value-1);
249 /// Log2_64 - This function returns the ceil log base 2 of the specified value,
250 /// 64 if the value is zero. (64 bit edition.)
251 inline unsigned Log2_64_Ceil(uint64_t Value) {
252 return 64-CountLeadingZeros_64(Value-1);
255 /// GreatestCommonDivisor64 - Return the greatest common divisor of the two
256 /// values using Euclid's algorithm.
257 inline uint64_t GreatestCommonDivisor64(uint64_t A, uint64_t B) {
266 /// BitsToDouble - This function takes a 64-bit integer and returns the bit
267 /// equivalent double.
268 inline double BitsToDouble(uint64_t Bits) {
277 /// BitsToFloat - This function takes a 32-bit integer and returns the bit
278 /// equivalent float.
279 inline float BitsToFloat(uint32_t Bits) {
288 /// DoubleToBits - This function takes a double and returns the bit
289 /// equivalent 64-bit integer.
290 inline uint64_t DoubleToBits(double Double) {
299 /// FloatToBits - This function takes a float and returns the bit
300 /// equivalent 32-bit integer.
301 inline uint32_t FloatToBits(float Float) {
310 /// Platform-independent wrappers for the C99 isnan() function.
314 /// Platform-independent wrappers for the C99 isinf() function.
318 } // End llvm namespace