gdb/gmp-utils.h

/* Miscellaneous routines making it easier to use GMP within GDB's framework.

   Copyright (C) 2019-2023 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#ifndef GMP_UTILS_H
#define GMP_UTILS_H

/* Include <stdio.h> and <stdarg.h> ahead of <gmp.h>, so as to get
   access to GMP's various formatting functions.  */
#include <stdio.h>
#include <stdarg.h>
#include <gmp.h>
#include "gdbsupport/traits.h"

/* Same as gmp_asprintf, but returning an std::string.  */

std::string gmp_string_printf (const char *fmt, ...);

struct gdb_mpq;
struct gdb_mpf;

/* A class to make it easier to use GMP's mpz_t values within GDB.  */

struct gdb_mpz
{
  /* Constructors.  */
  gdb_mpz () { mpz_init (m_val); }

  explicit gdb_mpz (const mpz_t &from_val)
  {
    mpz_init (m_val);
    mpz_set (m_val, from_val);
  }

  gdb_mpz (const gdb_mpz &from)
  {
    mpz_init (m_val);
    mpz_set (m_val, from.m_val);
  }

  /* Initialize using the given integral value.

     The main advantage of this method is that it handles both signed
     and unsigned types, with no size restriction.  */
  template<typename T, typename = gdb::Requires<std::is_integral<T>>>
  explicit gdb_mpz (T src)
  {
    mpz_init (m_val);
    set (src);
  }

  explicit gdb_mpz (gdb_mpz &&from)
  {
    mpz_init (m_val);
    mpz_swap (m_val, from.m_val);
  }

  
  gdb_mpz &operator= (const gdb_mpz &from)
  {
    mpz_set (m_val, from.m_val);
    return *this;
  }

  gdb_mpz &operator= (gdb_mpz &&other)
  {
    mpz_swap (m_val, other.m_val);
    return *this;
  }

  template<typename T, typename = gdb::Requires<std::is_integral<T>>>
  gdb_mpz &operator= (T src)
  {
    set (src);
    return *this;
  }

  gdb_mpz &operator= (bool src)
  {
    mpz_set_ui (m_val, (unsigned long) src);
    return *this;
  }

  /* Initialize this value from a string and a base.  Returns true if
     the string was parsed successfully, false otherwise.  */
  bool set (const char *str, int base)
  {
    return mpz_set_str (m_val, str, base) != -1;
  }

  /* Return a new value that is BASE**EXP.  */
  static gdb_mpz pow (unsigned long base, unsigned long exp)
  {
    gdb_mpz result;
    mpz_ui_pow_ui (result.m_val, base, exp);
    return result;
  }

  /* Return a new value that is this value raised to EXP.  */
  gdb_mpz pow (unsigned long exp) const
  {
    gdb_mpz result;
    mpz_pow_ui (result.m_val, m_val, exp);
    return result;
  }

  /* Convert this value to an integer of the given type.

     The return type can signed or unsigned, with no size restriction.  */
  template<typename T> T as_integer () const;

  /* Convert this value to an integer of the given type.  If this
     value is too large, it is truncated.

     The return type can signed or unsigned, with no size restriction.  */
  template<typename T> T as_integer_truncate () const;

  /* Set VAL by importing the number stored in the byte array (BUF),
     using the given BYTE_ORDER.  The size of the data to read is
     the byte array's size.

     UNSIGNED_P indicates whether the number has an unsigned type.  */
  void read (gdb::array_view<const gdb_byte> buf, enum bfd_endian byte_order,
	     bool unsigned_p);

  /* Write VAL into BUF as a number whose byte size is the size of BUF,
     using the given BYTE_ORDER.

     UNSIGNED_P indicates whether the number has an unsigned type.  */
  void write (gdb::array_view<gdb_byte> buf, enum bfd_endian byte_order,
	      bool unsigned_p) const
  {
    export_bits (buf, byte_order == BFD_ENDIAN_BIG ? 1 : -1 /* endian */,
		 unsigned_p, true /* safe */);
  }

  /* Like write, but truncates the value to the desired number of
     bytes.  */
  void truncate (gdb::array_view<gdb_byte> buf, enum bfd_endian byte_order,
		 bool unsigned_p) const
  {
    export_bits (buf, byte_order == BFD_ENDIAN_BIG ? 1 : -1 /* endian */,
		 unsigned_p, false /* safe */);
  }

  /* Return a string containing VAL.  */
  std::string str () const { return gmp_string_printf ("%Zd", m_val); }

  /* The destructor.  */
  ~gdb_mpz () { mpz_clear (m_val); }

  /* Negate this value in place.  */
  void negate ()
  {
    mpz_neg (m_val, m_val);
  }

  /* Take the one's complement in place.  */
  void complement ()
  { mpz_com (m_val, m_val); }

  /* Mask this value to N bits, in place.  */
  void mask (unsigned n)
  { mpz_tdiv_r_2exp (m_val, m_val, n); }

  /* Return the sign of this value.  This returns -1 for a negative
     value, 0 if the value is 0, and 1 for a positive value.  */
  int sgn () const
  { return mpz_sgn (m_val); }

  explicit operator bool () const
  { return sgn () != 0; }

  gdb_mpz &operator*= (long other)
  {
    mpz_mul_si (m_val, m_val, other);
    return *this;
  }

  gdb_mpz operator* (const gdb_mpz &other) const
  {
    gdb_mpz result;
    mpz_mul (result.m_val, m_val, other.m_val);
    return result;
  }

  gdb_mpz operator/ (const gdb_mpz &other) const
  {
    gdb_mpz result;
    mpz_tdiv_q (result.m_val, m_val, other.m_val);
    return result;
  }

  gdb_mpz operator% (const gdb_mpz &other) const
  {
    gdb_mpz result;
    mpz_tdiv_r (result.m_val, m_val, other.m_val);
    return result;
  }

  gdb_mpz &operator+= (unsigned long other)
  {
    mpz_add_ui (m_val, m_val, other);
    return *this;
  }

  gdb_mpz &operator+= (const gdb_mpz &other)
  {
    mpz_add (m_val, m_val, other.m_val);
    return *this;
  }

  gdb_mpz operator+ (const gdb_mpz &other) const
  {
    gdb_mpz result;
    mpz_add (result.m_val, m_val, other.m_val);
    return result;
  }

  gdb_mpz &operator-= (unsigned long other)
  {
    mpz_sub_ui (m_val, m_val, other);
    return *this;
  }

  gdb_mpz &operator-= (const gdb_mpz &other)
  {
    mpz_sub (m_val, m_val, other.m_val);
    return *this;
  }

  gdb_mpz operator- (const gdb_mpz &other) const
  {
    gdb_mpz result;
    mpz_sub (result.m_val, m_val, other.m_val);
    return result;
  }

  gdb_mpz &operator<<= (unsigned long nbits)
  {
    mpz_mul_2exp (m_val, m_val, nbits);
    return *this;
  }

  gdb_mpz operator<< (unsigned long nbits) const
  {
    gdb_mpz result;
    mpz_mul_2exp (result.m_val, m_val, nbits);
    return result;
  }

  gdb_mpz operator>> (unsigned long nbits) const
  {
    gdb_mpz result;
    mpz_tdiv_q_2exp (result.m_val, m_val, nbits);
    return result;
  }

  gdb_mpz &operator>>= (unsigned long nbits)
  {
    mpz_tdiv_q_2exp (m_val, m_val, nbits);
    return *this;
  }

  gdb_mpz operator& (const gdb_mpz &other) const
  {
    gdb_mpz result;
    mpz_and (result.m_val, m_val, other.m_val);
    return result;
  }

  gdb_mpz operator| (const gdb_mpz &other) const
  {
    gdb_mpz result;
    mpz_ior (result.m_val, m_val, other.m_val);
    return result;
  }

  gdb_mpz operator^ (const gdb_mpz &other) const
  {
    gdb_mpz result;
    mpz_xor (result.m_val, m_val, other.m_val);
    return result;
  }

  bool operator> (const gdb_mpz &other) const
  {
    return mpz_cmp (m_val, other.m_val) > 0;
  }

  bool operator>= (const gdb_mpz &other) const
  {
    return mpz_cmp (m_val, other.m_val) >= 0;
  }

  bool operator< (const gdb_mpz &other) const
  {
    return mpz_cmp (m_val, other.m_val) < 0;
  }

  bool operator<= (const gdb_mpz &other) const
  {
    return mpz_cmp (m_val, other.m_val) <= 0;
  }

  bool operator< (long other) const
  {
    return mpz_cmp_si (m_val, other) < 0;
  }

  /* We want an operator== that can handle all integer types.  For
     types that are 'long' or narrower, we can use a GMP function and
     avoid boxing the RHS.  But, because overloading based on integer
     type is a pain in C++, we accept all such types here and check
     the size in the body.  */
  template<typename T, typename = gdb::Requires<std::is_integral<T>>>
  bool operator== (T other) const
  {
    if (std::is_signed<T>::value)
      {
	if (sizeof (T) <= sizeof (long))
	  return mpz_cmp_si (m_val, other) == 0;
      }
    else
      {
	if (sizeof (T) <= sizeof (unsigned long))
	  return mpz_cmp_ui (m_val, other) == 0;
      }
    return *this == gdb_mpz (other);
  }

  bool operator== (const gdb_mpz &other) const
  {
    return mpz_cmp (m_val, other.m_val) == 0;
  }

  bool operator!= (const gdb_mpz &other) const
  {
    return mpz_cmp (m_val, other.m_val) != 0;
  }

private:

  /* Helper template for constructor and operator=.  */
  template<typename T> void set (T src);

  /* Low-level function to export VAL into BUF as a number whose byte size
     is the size of BUF.

     If UNSIGNED_P is true, then export VAL into BUF as an unsigned value.
     Otherwise, export it as a signed value.

     The API is inspired from GMP's mpz_export, hence the naming and types
     of the following parameter:
       - ENDIAN should be:
	   . 1 for most significant byte first; or
	   . -1 for least significant byte first; or
	   . 0 for native endianness.

    If SAFE is true, an error is raised if BUF is not large enough to
    contain the value being exported.  If SAFE is false, the value is
    truncated to fit in BUF.  */
  void export_bits (gdb::array_view<gdb_byte> buf, int endian, bool unsigned_p,
		    bool safe) const;

  friend struct gdb_mpq;
  friend struct gdb_mpf;

  mpz_t m_val;
};

/* A class to make it easier to use GMP's mpq_t values within GDB.  */

struct gdb_mpq
{
  /* Constructors.  */
  gdb_mpq () { mpq_init (m_val); }

  explicit gdb_mpq (const mpq_t &from_val)
  {
    mpq_init (m_val);
    mpq_set (m_val, from_val);
  }

  gdb_mpq (const gdb_mpq &from)
  {
    mpq_init (m_val);
    mpq_set (m_val, from.m_val);
  }

  explicit gdb_mpq (gdb_mpq &&from)
  {
    mpq_init (m_val);
    mpq_swap (m_val, from.m_val);
  }

  gdb_mpq (const gdb_mpz &num, const gdb_mpz &denom)
  {
    mpq_init (m_val);
    mpz_set (mpq_numref (m_val), num.m_val);
    mpz_set (mpq_denref (m_val), denom.m_val);
    mpq_canonicalize (m_val);
  }

  gdb_mpq (long num, long denom)
  {
    mpq_init (m_val);
    mpq_set_si (m_val, num, denom);
    mpq_canonicalize (m_val);
  }

  /* Copy assignment operator.  */
  gdb_mpq &operator= (const gdb_mpq &from)
  {
    mpq_set (m_val, from.m_val);
    return *this;
  }

  gdb_mpq &operator= (gdb_mpq &&from)
  {
    mpq_swap (m_val, from.m_val);
    return *this;
  }

  gdb_mpq &operator= (const gdb_mpz &from)
  {
    mpq_set_z (m_val, from.m_val);
    return *this;
  }

  gdb_mpq &operator= (double d)
  {
    mpq_set_d (m_val, d);
    return *this;
  }

  /* Return the sign of this value.  This returns -1 for a negative
     value, 0 if the value is 0, and 1 for a positive value.  */
  int sgn () const
  { return mpq_sgn (m_val); }

  gdb_mpq operator+ (const gdb_mpq &other) const
  {
    gdb_mpq result;
    mpq_add (result.m_val, m_val, other.m_val);
    return result;
  }

  gdb_mpq operator- (const gdb_mpq &other) const
  {
    gdb_mpq result;
    mpq_sub (result.m_val, m_val, other.m_val);
    return result;
  }

  gdb_mpq operator* (const gdb_mpq &other) const
  {
    gdb_mpq result;
    mpq_mul (result.m_val, m_val, other.m_val);
    return result;
  }

  gdb_mpq operator/ (const gdb_mpq &other) const
  {
    gdb_mpq result;
    mpq_div (result.m_val, m_val, other.m_val);
    return result;
  }

  gdb_mpq &operator*= (const gdb_mpq &other)
  {
    mpq_mul (m_val, m_val, other.m_val);
    return *this;
  }

  gdb_mpq &operator/= (const gdb_mpq &other)
  {
    mpq_div (m_val, m_val, other.m_val);
    return *this;
  }

  bool operator== (const gdb_mpq &other) const
  {
    return mpq_cmp (m_val, other.m_val) == 0;
  }

  bool operator< (const gdb_mpq &other) const
  {
    return mpq_cmp (m_val, other.m_val) < 0;
  }

  /* Return a string representing VAL as "<numerator> / <denominator>".  */
  std::string str () const { return gmp_string_printf ("%Qd", m_val); }

  /* Return VAL rounded to the nearest integer.  */
  gdb_mpz get_rounded () const;

  /* Return this value as an integer, rounded toward zero.  */
  gdb_mpz as_integer () const
  {
    gdb_mpz result;
    mpz_tdiv_q (result.m_val, mpq_numref (m_val), mpq_denref (m_val));
    return result;
  }

  /* Return this value converted to a host double.  */
  double as_double () const
  { return mpq_get_d (m_val); }

  /* Set VAL from the contents of the given byte array (BUF), which
     contains the unscaled value of a fixed point type object.
     The byte size of the data is the size of BUF.

     BYTE_ORDER provides the byte_order to use when reading the data.

     UNSIGNED_P indicates whether the number has an unsigned type.
     SCALING_FACTOR is the scaling factor to apply after having
     read the unscaled value from our buffer.  */
  void read_fixed_point (gdb::array_view<const gdb_byte> buf,
			 enum bfd_endian byte_order, bool unsigned_p,
			 const gdb_mpq &scaling_factor);

  /* Write VAL into BUF as fixed point value following the given BYTE_ORDER.
     The size of BUF is used as the length to write the value into.

     UNSIGNED_P indicates whether the number has an unsigned type.
     SCALING_FACTOR is the scaling factor to apply before writing
     the unscaled value to our buffer.  */
  void write_fixed_point (gdb::array_view<gdb_byte> buf,
			  enum bfd_endian byte_order, bool unsigned_p,
			  const gdb_mpq &scaling_factor) const;

  /* The destructor.  */
  ~gdb_mpq () { mpq_clear (m_val); }

private:

  friend struct gdb_mpf;

  mpq_t m_val;
};

/* A class to make it easier to use GMP's mpf_t values within GDB.

   Should MPFR become a required dependency, we should probably
   drop this class in favor of using MPFR.  */

struct gdb_mpf
{
  /* Constructors.  */
  gdb_mpf () { mpf_init (m_val); }

  DISABLE_COPY_AND_ASSIGN (gdb_mpf);

  /* Set VAL from the contents of the given buffer (BUF), which
     contains the unscaled value of a fixed point type object
     with the given size (LEN) and byte order (BYTE_ORDER).

     UNSIGNED_P indicates whether the number has an unsigned type.
     SCALING_FACTOR is the scaling factor to apply after having
     read the unscaled value from our buffer.  */
  void read_fixed_point (gdb::array_view<const gdb_byte> buf,
			 enum bfd_endian byte_order, bool unsigned_p,
			 const gdb_mpq &scaling_factor)
  {
    gdb_mpq tmp_q;

    tmp_q.read_fixed_point (buf, byte_order, unsigned_p, scaling_factor);
    mpf_set_q (m_val, tmp_q.m_val);
  }

  /* Convert this value to a string.  FMT is the format to use, and
     should have a single '%' substitution.  */
  std::string str (const char *fmt) const
  { return gmp_string_printf (fmt, m_val); }

  /* The destructor.  */
  ~gdb_mpf () { mpf_clear (m_val); }

private:

  mpf_t m_val;
};

/* See declaration above.  */

template<typename T>
void
gdb_mpz::set (T src)
{
  mpz_import (m_val, 1 /* count */, -1 /* order */,
	      sizeof (T) /* size */, 0 /* endian (0 = native) */,
	      0 /* nails */, &src /* op */);
  if (std::is_signed<T>::value && src < 0)
    {
      /* mpz_import does not handle the sign, so our value was imported
	 as an unsigned. Adjust that imported value so as to make it
	 the correct negative value.  */
      gdb_mpz neg_offset;

      mpz_ui_pow_ui (neg_offset.m_val, 2, sizeof (T) * HOST_CHAR_BIT);
      mpz_sub (m_val, m_val, neg_offset.m_val);
    }
}

/* See declaration above.  */

template<typename T>
T
gdb_mpz::as_integer () const
{
  T result;

  this->export_bits ({(gdb_byte *) &result, sizeof (result)},
		     0 /* endian (0 = native) */,
		     !std::is_signed<T>::value /* unsigned_p */,
		     true /* safe */);

  return result;
}

/* See declaration above.  */

template<typename T>
T
gdb_mpz::as_integer_truncate () const
{
  T result;

  this->export_bits ({(gdb_byte *) &result, sizeof (result)},
		     0 /* endian (0 = native) */,
		     !std::is_signed<T>::value /* unsigned_p */,
		     false /* safe */);

  return result;
}

#endif