/src/capstonenext/MathExtras.h

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//===-- llvm/Support/MathExtras.h - Useful math functions -------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains some functions that are useful for math stuff.
//
//===----------------------------------------------------------------------===//

/* Capstone Disassembly Engine */
/* By Nguyen Anh Quynh <aquynh@gmail.com>, 2013-2019 */

#ifndef CS_LLVM_SUPPORT_MATHEXTRAS_H
#define CS_LLVM_SUPPORT_MATHEXTRAS_H

#if defined(_WIN32_WCE) && (_WIN32_WCE < 0x800)
#include "windowsce/intrin.h"
#elif defined(_MSC_VER)
#include <intrin.h>
#endif

#ifndef __cplusplus
#ifdef _MSC_VER
#define inline /* inline */
#endif
#endif

#include <limits.h>

// NOTE: The following support functions use the _32/_64 extensions instead of
// type overloading so that signed and unsigned integers can be used without
// ambiguity.

/// Hi_32 - This function returns the high 32 bits of a 64 bit value.
static inline uint32_t Hi_32(uint64_t Value)
{
  return (uint32_t)(Value >> 32);
}

/// Lo_32 - This function returns the low 32 bits of a 64 bit value.
static inline uint32_t Lo_32(uint64_t Value)
{
  return (uint32_t)(Value);
}

/// isUIntN - Checks if an unsigned integer fits into the given (dynamic)
/// bit width.
static inline bool isUIntN(unsigned N, uint64_t x)
{
  return x == (x & (~0ULL >> (64 - N)));
}

/// isIntN - Checks if an signed integer fits into the given (dynamic)
/// bit width.
static inline bool isIntN(unsigned N, int64_t x)
{
  return N >= 64 ||
         (-(INT64_C(1) << (N - 1)) <= x && x < (INT64_C(1) << (N - 1)));
}

/// isMask_32 - This function returns true if the argument is a sequence of ones
/// starting at the least significant bit with the remainder zero (32 bit
/// version).   Ex. isMask_32(0x0000FFFFU) == true.
static inline bool isMask_32(uint32_t Value)
{
  return Value && ((Value + 1) & Value) == 0;
}

/// isMask_64 - This function returns true if the argument is a sequence of ones
/// starting at the least significant bit with the remainder zero (64 bit
/// version).
static inline bool isMask_64(uint64_t Value)
{
  return Value && ((Value + 1) & Value) == 0;
}

/// isShiftedMask_32 - This function returns true if the argument contains a
/// sequence of ones with the remainder zero (32 bit version.)
/// Ex. isShiftedMask_32(0x0000FF00U) == true.
static inline bool isShiftedMask_32(uint32_t Value)
{
  return isMask_32((Value - 1) | Value);
}

/// isShiftedMask_64 - This function returns true if the argument contains a
/// sequence of ones with the remainder zero (64 bit version.)
static inline bool isShiftedMask_64(uint64_t Value)
{
  return isMask_64((Value - 1) | Value);
}

/// isPowerOf2_32 - This function returns true if the argument is a power of
/// two > 0. Ex. isPowerOf2_32(0x00100000U) == true (32 bit edition.)
static inline bool isPowerOf2_32(uint32_t Value)
{
  return Value && !(Value & (Value - 1));
}

/// CountLeadingZeros_32 - this function performs the platform optimal form of
/// counting the number of zeros from the most significant bit to the first one
/// bit.  Ex. CountLeadingZeros_32(0x00F000FF) == 8.
/// Returns 32 if the word is zero.
static inline unsigned CountLeadingZeros_32(uint32_t Value)
{
  unsigned Count; // result
#if __GNUC__ >= 4
  // PowerPC is defined for __builtin_clz(0)
#if !defined(__ppc__) && !defined(__ppc64__)
  if (!Value)
    return 32;
#endif
  Count = __builtin_clz(Value);
#else
  unsigned Shift;
  if (!Value)
    return 32;
  Count = 0;
  // bisection method for count leading zeros
  for (Shift = 32 >> 1; Shift; Shift >>= 1) {
    uint32_t Tmp = Value >> Shift;
    if (Tmp) {
      Value = Tmp;
    } else {
      Count |= Shift;
    }
  }
#endif
  return Count;
}

/// CountLeadingOnes_32 - this function performs the operation of
/// counting the number of ones from the most significant bit to the first zero
/// bit.  Ex. CountLeadingOnes_32(0xFF0FFF00) == 8.
/// Returns 32 if the word is all ones.
static inline unsigned CountLeadingOnes_32(uint32_t Value)
{
  return CountLeadingZeros_32(~Value);
}

/// CountLeadingZeros_64 - This function performs the platform optimal form
/// of counting the number of zeros from the most significant bit to the first
/// one bit (64 bit edition.)
/// Returns 64 if the word is zero.
static inline unsigned CountLeadingZeros_64(uint64_t Value)
{
  unsigned Count; // result
#if __GNUC__ >= 4
  // PowerPC is defined for __builtin_clzll(0)
#if !defined(__ppc__) && !defined(__ppc64__)
  if (!Value)
    return 64;
#endif
  Count = __builtin_clzll(Value);
#else
#ifndef _MSC_VER
  unsigned Shift;
  if (sizeof(long) == sizeof(int64_t)) {
    if (!Value)
      return 64;
    Count = 0;
    // bisection method for count leading zeros
    for (Shift = 64 >> 1; Shift; Shift >>= 1) {
      uint64_t Tmp = Value >> Shift;
      if (Tmp) {
        Value = Tmp;
      } else {
        Count |= Shift;
      }
    }
  } else
#endif
  {
    // get hi portion
    uint32_t Hi = Hi_32(Value);

    // if some bits in hi portion
    if (Hi) {
      // leading zeros in hi portion plus all bits in lo portion
      Count = CountLeadingZeros_32(Hi);
    } else {
      // get lo portion
      uint32_t Lo = Lo_32(Value);
      // same as 32 bit value
      Count = CountLeadingZeros_32(Lo) + 32;
    }
  }
#endif
  return Count;
}

/// CountLeadingOnes_64 - This function performs the operation
/// of counting the number of ones from the most significant bit to the first
/// zero bit (64 bit edition.)
/// Returns 64 if the word is all ones.
static inline unsigned CountLeadingOnes_64(uint64_t Value)
{
  return CountLeadingZeros_64(~Value);
}

/// CountTrailingZeros_32 - this function performs the platform optimal form of
/// counting the number of zeros from the least significant bit to the first one
/// bit.  Ex. CountTrailingZeros_32(0xFF00FF00) == 8.
/// Returns 32 if the word is zero.
static inline unsigned CountTrailingZeros_32(uint32_t Value)
{
#if __GNUC__ >= 4
  return Value ? __builtin_ctz(Value) : 32;
#else
  static const unsigned Mod37BitPosition[] = {
    32, 0, 1,  26, 2,  23, 27, 0,  3,  16, 24, 30, 28,
    11, 0, 13, 4,  7,  17, 0,  25, 22, 31, 15, 29, 10,
    12, 6, 0,  21, 14, 9,  5,  20, 8,  19, 18
  };
  // Replace "-Value" by "1+~Value" in the following commented code to avoid
  // MSVC warning C4146
  //    return Mod37BitPosition[(-Value & Value) % 37];
  return Mod37BitPosition[((1 + ~Value) & Value) % 37];
#endif
}

// Count trailing zeros as in:
// https://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightParallel
static inline unsigned CountTrailingZeros_8(uint8_t Value)
{
  uint8_t c = 8;
  Value &= -((int8_t)Value);
  if (Value)
    c--;
  if (Value & 0x0F)
    c -= 4;
  if (Value & 0x33)
    c -= 2;
  if (Value & 0x55)
    c -= 1;
  return c;
}

/// CountTrailingOnes_32 - this function performs the operation of
/// counting the number of ones from the least significant bit to the first zero
/// bit.  Ex. CountTrailingOnes_32(0x00FF00FF) == 8.
/// Returns 32 if the word is all ones.
static inline unsigned CountTrailingOnes_32(uint32_t Value)
{
  return CountTrailingZeros_32(~Value);
}

/// CountTrailingZeros_64 - This function performs the platform optimal form
/// of counting the number of zeros from the least significant bit to the first
/// one bit (64 bit edition.)
/// Returns 64 if the word is zero.
static inline unsigned CountTrailingZeros_64(uint64_t Value)
{
#if __GNUC__ >= 4
  return Value ? __builtin_ctzll(Value) : 64;
#else
  static const unsigned Mod67Position[] = {
    64, 0,  1,  39, 2,  15, 40, 23, 3,  12, 16, 59, 41, 19,
    24, 54, 4,  64, 13, 10, 17, 62, 60, 28, 42, 30, 20, 51,
    25, 44, 55, 47, 5,  32, 65, 38, 14, 22, 11, 58, 18, 53,
    63, 9,  61, 27, 29, 50, 43, 46, 31, 37, 21, 57, 52, 8,
    26, 49, 45, 36, 56, 7,  48, 35, 6,  34, 33, 0
  };
  // Replace "-Value" by "1+~Value" in the following commented code to avoid
  // MSVC warning C4146
  //    return Mod67Position[(-Value & Value) % 67];
  return Mod67Position[((1 + ~Value) & Value) % 67];
#endif
}

/// CountTrailingOnes_64 - This function performs the operation
/// of counting the number of ones from the least significant bit to the first
/// zero bit (64 bit edition.)
/// Returns 64 if the word is all ones.
static inline unsigned CountTrailingOnes_64(uint64_t Value)
{
  return CountTrailingZeros_64(~Value);
}

/// CountPopulation_32 - this function counts the number of set bits in a value.
/// Ex. CountPopulation(0xF000F000) = 8
/// Returns 0 if the word is zero.
static inline unsigned CountPopulation_32(uint32_t Value)
{
#if __GNUC__ >= 4
  return __builtin_popcount(Value);
#else
  uint32_t v = Value - ((Value >> 1) & 0x55555555);
  v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
  return (((v + (v >> 4)) & 0xF0F0F0F) * 0x1010101) >> 24;
#endif
}

/// CountPopulation_64 - this function counts the number of set bits in a value,
/// (64 bit edition.)
static inline unsigned CountPopulation_64(uint64_t Value)
{
#if __GNUC__ >= 4
  return __builtin_popcountll(Value);
#else
  uint64_t v = Value - ((Value >> 1) & 0x5555555555555555ULL);
  v = (v & 0x3333333333333333ULL) + ((v >> 2) & 0x3333333333333333ULL);
  v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL;
  return (uint64_t)((v * 0x0101010101010101ULL) >> 56);
#endif
}

/// Log2_32 - This function returns the floor log base 2 of the specified value,
/// UINT_MAX if the value is zero. (32 bit edition.)
/// Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1, Log2_32(6) == 2
static inline unsigned Log2_32(uint32_t Value)
{
  if (Value == 0) {
    return UINT_MAX;
  }
  return 31 - CountLeadingZeros_32(Value);
}

/// Log2_64 - This function returns the floor log base 2 of the specified value,
/// UINT_MAX if the value is zero. (64 bit edition.)
static inline unsigned Log2_64(uint64_t Value)
{
  if (Value == 0) {
    return UINT32_MAX;
  }
  return 63 - CountLeadingZeros_64(Value);
}

/// Log2_32_Ceil - This function returns the ceil log base 2 of the specified
/// value, 32 if the value is zero. (32 bit edition).
/// Ex. Log2_32_Ceil(32) == 5, Log2_32_Ceil(1) == 0, Log2_32_Ceil(6) == 3
static inline unsigned Log2_32_Ceil(uint32_t Value)
{
  return 32 - CountLeadingZeros_32(Value - 1);
}

/// Log2_64_Ceil - This function returns the ceil log base 2 of the specified
/// value, 64 if the value is zero. (64 bit edition.)
static inline unsigned Log2_64_Ceil(uint64_t Value)
{
  return 64 - CountLeadingZeros_64(Value - 1);
}

/// GreatestCommonDivisor64 - Return the greatest common divisor of the two
/// values using Euclid's algorithm.
static inline uint64_t GreatestCommonDivisor64(uint64_t A, uint64_t B)
{
  while (B) {
    uint64_t T = B;
    B = A % B;
    A = T;
  }
  return A;
}

/// BitsToDouble - This function takes a 64-bit integer and returns the bit
/// equivalent double.
static inline double BitsToDouble(uint64_t Bits)
{
  union {
    uint64_t L;
    double D;
  } T;
  T.L = Bits;
  return T.D;
}

/// BitsToFloat - This function takes a 32-bit integer and returns the bit
/// equivalent float.
static inline float BitsToFloat(uint32_t Bits)
{
  union {
    uint32_t I;
    float F;
  } T;
  T.I = Bits;
  return T.F;
}

/// DoubleToBits - This function takes a double and returns the bit
/// equivalent 64-bit integer.  Note that copying doubles around
/// changes the bits of NaNs on some hosts, notably x86, so this
/// routine cannot be used if these bits are needed.
static inline uint64_t DoubleToBits(double Double)
{
  union {
    uint64_t L;
    double D;
  } T;
  T.D = Double;
  return T.L;
}

/// FloatToBits - This function takes a float and returns the bit
/// equivalent 32-bit integer.  Note that copying floats around
/// changes the bits of NaNs on some hosts, notably x86, so this
/// routine cannot be used if these bits are needed.
static inline uint32_t FloatToBits(float Float)
{
  union {
    uint32_t I;
    float F;
  } T;
  T.F = Float;
  return T.I;
}

/// MinAlign - A and B are either alignments or offsets.  Return the minimum
/// alignment that may be assumed after adding the two together.
static inline uint64_t MinAlign(uint64_t A, uint64_t B)
{
  // The largest power of 2 that divides both A and B.
  //
  // Replace "-Value" by "1+~Value" in the following commented code to avoid
  // MSVC warning C4146
  //    return (A | B) & -(A | B);
  return (A | B) & (1 + ~(A | B));
}

/// NextPowerOf2 - Returns the next power of two (in 64-bits)
/// that is strictly greater than A.  Returns zero on overflow.
static inline uint64_t NextPowerOf2(uint64_t A)
{
  A |= (A >> 1);
  A |= (A >> 2);
  A |= (A >> 4);
  A |= (A >> 8);
  A |= (A >> 16);
  A |= (A >> 32);
  return A + 1;
}

/// Returns the next integer (mod 2**64) that is greater than or equal to
/// \p Value and is a multiple of \p Align. \p Align must be non-zero.
///
/// Examples:
/// \code
///   RoundUpToAlignment(5, 8) = 8
///   RoundUpToAlignment(17, 8) = 24
///   RoundUpToAlignment(~0LL, 8) = 0
/// \endcode
static inline uint64_t RoundUpToAlignment(uint64_t Value, uint64_t Align)
{
  return ((Value + Align - 1) / Align) * Align;
}

/// Returns the offset to the next integer (mod 2**64) that is greater than
/// or equal to \p Value and is a multiple of \p Align. \p Align must be
/// non-zero.
static inline uint64_t OffsetToAlignment(uint64_t Value, uint64_t Align)
{
  return RoundUpToAlignment(Value, Align) - Value;
}

/// abs64 - absolute value of a 64-bit int.  Not all environments support
/// "abs" on whatever their name for the 64-bit int type is.  The absolute
/// value of the largest negative number is undefined, as with "abs".
static inline int64_t abs64(int64_t x)
{
  return (x < 0) ? -x : x;
}

/// \brief Sign extend number in the bottom B bits of X to a 32-bit int.
/// Requires 0 < B <= 32.
/// Note that this implementation relies on right shift of signed
/// integers being an arithmetic shift.
static inline int32_t SignExtend32(uint32_t X, unsigned B)
{
  return (int32_t)(X << (32 - B)) >> (32 - B);
}

/// \brief Sign extend number in the bottom B bits of X to a 64-bit int.
/// Requires 0 < B <= 64.
/// Note that this implementation relies on right shift of signed
/// integers being an arithmetic shift.
static inline int64_t SignExtend64(uint64_t X, unsigned B)
{
  return (int64_t)(X << (64 - B)) >> (64 - B);
}

/// \brief Removes the rightmost bit of x and extends the field to the left with that
/// bit to form a 64-bit quantity. The field is of size len
static inline int64_t LowSignExtend64(uint64_t x, unsigned len)
{
  return (x >> 1) - ((x & 1) << (len - 1));
}

/// \brief One extend number X starting at bit B and returns it as int32_t.
/// Requires 0 < B <= 32.
static inline int32_t OneExtend32(uint32_t X, unsigned B)
{
  return (~0U << B) | X;
}

/// \brief One extend number X starting at bit B and returns it as int64_t.
/// Requires 0 < B <= 64.
static inline int64_t OneExtend64(uint64_t X, unsigned B)
{
  return (~0ULL << B) | X;
}

/// \brief Count number of 0's from the most significant bit to the least
///   stopping at the first 1.
///
/// Only unsigned integral types are allowed.
///
/// \param ZB the behavior on an input of 0. Only ZB_Width and ZB_Undefined are
///   valid arguments.
static inline unsigned int countLeadingZeros(int x)
{
  int i;
  const unsigned bits = sizeof(x) * 8;
  unsigned count = bits;

  if (x < 0) {
    return 0;
  }
  for (i = bits; --i;) {
    if (x == 0)
      break;
    count--;
    x >>= 1;
  }

  return count;
}

/// \brief Get specified field from 32-bit instruction. Returns bits from the segment [from, to]
/// The right most bit of insn is bit 31.
static inline uint32_t get_insn_field(uint32_t insn, uint8_t from, uint8_t to)
{
  return insn >> (31 - to) & ((1 << (to - from + 1)) - 1);
}

/// \brief Get specified field from 32-bit instruction. Returns bits from the segment [from, to]
/// The right most bit of insn is bit 0.
static inline uint32_t get_insn_field_r(uint32_t insn, uint8_t from, uint8_t to)
{
  return insn >> from & ((1 << (to - from + 1)) - 1);
}

/// \brief Get specified bit from 32-bit instruction
static inline uint32_t get_insn_bit(uint32_t insn, uint8_t bit)
{
  return get_insn_field(insn, bit, bit);
}

/// \brief Create a bitmask with the N right-most bits set to 1, and all other
/// bits set to 0.  Only unsigned types are allowed.
static inline uint32_t maskTrailingOnes32(uint32_t N)
{
  const unsigned Bits = CHAR_BIT * sizeof(uint32_t);
  return N == 0 ? 0 : (((uint32_t)-1) >> (Bits - N));
}

#endif

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