verinum.h

#ifndef __verinum_H
#define __verinum_H
/*
 * Copyright (c) 1998-2008 Stephen Williams (steve@icarus.com)
 *
 *    This source code is free software; you can redistribute it
 *    and/or modify it in source code form under the terms of the GNU
 *    General Public License as published by the Free Software
 *    Foundation; either version 2 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, write to the Free Software
 *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

# include  <string>

# include  "config.h"
#ifdef HAVE_IOSFWD
# include  <iosfwd>
#else
class ostream;
#endif

using namespace std;

/*
 * Numbers in Verilog are multibit strings, where each bit has 4
 * possible values: 0, 1, x or z. The verinum number is store in
 * little-endian format. This means that if the long value is 2b'10,
 * get(0) is 0 and get(1) is 1.
 */
class verinum {

    public:
      enum V { V0 = 0, V1, Vx, Vz };

      verinum();
      verinum(const string&str);
      verinum(const V*v, unsigned nbits, bool has_len =true);
      verinum(V, unsigned nbits =1, bool has_len =true);
      verinum(uint64_t val, unsigned bits);
      verinum(double val, bool dummy);
      verinum(const verinum&);

	// Create a signed number, with an unspecified number of bits.
      explicit verinum(int64_t val);

	// Copy only the specified number of bits from the
	// source. Also mark this number as has_len.
      verinum(const verinum&, unsigned bits);

      ~verinum();
      verinum& operator= (const verinum&);

	// Number of significant bits in this number.
      unsigned len() const { return nbits_; }

	// A number "has a length" if the length was specified fixed
	// in some way.
      bool has_len() const { return has_len_; }

      bool has_sign(bool flag) { has_sign_ = flag; return has_sign_; }
      bool has_sign() const { return has_sign_; }

	// A number is "defined" if there are no x or z bits in its value.
      bool is_defined() const;
      bool is_zero() const;
      bool is_negative() const;

	// A number is "a string" if its value came directly from
	// an ASCII description instead of a number value.
      bool is_string() const { return string_flag_; }

	// Comparison for use in sorting algorithms.
      bool is_before(const verinum&that) const;

	// Individual bits can be accessed with the get and set
	// methods.
      V get(unsigned idx) const;
      V set(unsigned idx, V val);

      V operator[] (unsigned idx) const { return get(idx); }


      uint64_t as_ulong64() const;
      unsigned long as_ulong() const;
      signed long   as_long() const;
      double as_double() const;
      string as_string() const;
    private:
      void signed_trim();

    private:
      V* bits_;
      unsigned nbits_;
      bool has_len_;
      bool has_sign_;

	// These are some convenience flags that help us do a better
	// job of pretty-printing values.
      bool string_flag_;
};

/*
 * This returns the sign bit of the verinum value. If the value is
 * unsigned, then return an implicit sign bit of 0. Otherwise, return
 * the high bit.
 */
inline verinum::V sign_bit(const verinum&val)
{
      if (val.has_sign())
	    return val.get(val.len()-1);
      else
	    return verinum::V0;
}

/* Return a verinum that has the same value as the input, but is at
   least as wide as the requested width. This may involve sign
   extension, if the value is signed. */
extern verinum pad_to_width(const verinum&, unsigned width);

/* Return a verinum that is minimal. That is, it has only the length
   needed to accurately represent the contained value, signed or not. */
extern verinum trim_vnum(const verinum&);

extern ostream& operator<< (ostream&, const verinum&);
extern ostream& operator<< (ostream&, verinum::V);

inline verinum::V bit4_z2x(verinum::V bit)
{ return bit<2? bit : verinum::Vx; /* Relies on V0 and V1 being <2 */}

extern verinum::V operator ~ (verinum::V l);
extern verinum::V operator | (verinum::V l, verinum::V r);
extern verinum::V operator & (verinum::V l, verinum::V r);
extern verinum::V operator ^ (verinum::V l, verinum::V r);

extern verinum::V operator == (const verinum&left, const verinum&right);
extern verinum::V operator <= (const verinum&left, const verinum&right);
extern verinum::V operator <  (const verinum&left, const verinum&right);

inline verinum::V operator > (const verinum&left, const verinum&right)
{ return right < left; }

inline verinum::V operator >= (const verinum&left, const verinum&right)
{ return right <= left; }

inline verinum::V operator != (const verinum&left, const verinum&right)
{ return (left == right)? verinum::V0 : verinum::V1; }


/* These are arithmetic operators. These generally work to produce
   results that do not overflow. That means the result may expand or
   contract to hold the bits needed to hold the operation results
   accurately. It is up to the caller to truncate or pad if a specific
   width is expected. */
extern verinum operator + (const verinum&left, const verinum&right);
extern verinum operator - (const verinum&left, const verinum&right);
extern verinum operator * (const verinum&left, const verinum&right);
extern verinum operator / (const verinum&left, const verinum&right);
extern verinum operator % (const verinum&left, const verinum&right);

extern verinum pow(const verinum&left, const verinum&right);

extern verinum operator<< (const verinum&left, unsigned shift);
extern verinum operator>> (const verinum&left, unsigned shift);

extern verinum concat(const verinum&left, const verinum&right);

/* Bitwise not returns the ones complement. */
extern verinum v_not(const verinum&left);

#endif