sc_nbutils.h

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/*****************************************************************************

  The following code is derived, directly or indirectly, from the SystemC
  source code Copyright (c) 1996-2014 by all Contributors.
  All Rights reserved.

  The contents of this file are subject to the restrictions and limitations
  set forth in the SystemC Open Source License (the "License");
  You may not use this file except in compliance with such restrictions and
  limitations. You may obtain instructions on how to receive a copy of the
  License at http://www.accellera.org/. Software distributed by Contributors
  under the License is distributed on an "AS IS" basis, WITHOUT WARRANTY OF
  ANY KIND, either express or implied. See the License for the specific
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 *****************************************************************************/

/*****************************************************************************

  sc_nbutils.h -- External and friend functions for both sc_signed and
                  sc_unsigned classes.

  Original Author: Ali Dasdan, Synopsys, Inc.
 
 *****************************************************************************/

/*****************************************************************************

  MODIFICATION LOG - modifiers, enter your name, affiliation, date and
  changes you are making here.

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// $Log: sc_nbutils.h,v $
// Revision 1.6  2011/09/08 16:12:15  acg
//  Philipp A. Hartmann: fix issue with Sun machines wrt real math libraries.
//
// Revision 1.5  2011/08/26 23:00:01  acg
//  Torsten Maehne: remove use of ieeefp.h.
//
// Revision 1.4  2011/08/15 16:43:24  acg
//  Torsten Maehne: changes to remove unused argument warnings.
//
// Revision 1.3  2011/02/18 20:19:15  acg
//  Andy Goodrich: updating Copyright notice.
//
// Revision 1.2  2010/09/06 16:35:48  acg
//  Andy Goodrich: changed i386 to __i386__ in ifdef's.
//
// Revision 1.1.1.1  2006/12/15 20:20:05  acg
// SystemC 2.3
//
// Revision 1.3  2006/01/13 18:49:32  acg
// Added $Log command so that CVS check in comments are reproduced in the
// source.
//

#ifndef SC_NBUTILS_H
#define SC_NBUTILS_H

#include <cmath>
#include <limits>

#include "sysc/datatypes/bit/sc_bit_ids.h"
#include "sysc/datatypes/int/sc_int_ids.h"
#include "sysc/datatypes/int/sc_nbdefs.h"
#include "sysc/utils/sc_report.h"


namespace sc_dt
{

//-----------------------------------------------------------------------------
//"sc_io_base"
//
// This inline function returns the type of an i/o stream's base as a SystemC
// base designator.
//   stream_object = reference to the i/o stream whose base is to be returned.
//
//"sc_io_show_base"
//
// This inline function returns true if the base should be shown when a SystemC
// value is displayed via the supplied stream operator.
//   stream_object = reference to the i/o stream to return showbase value for.
//-----------------------------------------------------------------------------
#if defined(__GNUC__) || defined(_MSC_VER) || defined(__SUNPRO_CC)
    inline sc_numrep
    sc_io_base( systemc_ostream& os, sc_numrep def_base )
    {
        std::ios::fmtflags flags = os.flags() & std::ios::basefield;
        if ( flags & ::std::ios::dec ) return  SC_DEC;
        if ( flags & ::std::ios::hex ) return  SC_HEX;
        if ( flags & ::std::ios::oct ) return  SC_OCT;
        return def_base;
    }

    inline bool
    sc_io_show_base( systemc_ostream& os )
    {
        return (os.flags() & ::std::ios::showbase) != 0 ;
    }
#else   // Other
    inline sc_numrep
    sc_io_base( systemc_ostream& /*unused*/, sc_numrep /*unused*/ )
    {
        return SC_DEC;
    }
    inline bool
    sc_io_show_base( systemc_ostream& /*unused*/ )
    {
        return false;
    }
#endif

const std::string to_string( sc_numrep );

inline
systemc_ostream&
operator << ( systemc_ostream& os, sc_numrep numrep )
{
    os << to_string( numrep );
    return os;
}

// only used within vec_from_str (non-standard, deprecated)
inline void
is_valid_base(sc_numrep base)
{
  switch (base) {
    case SC_NOBASE: case SC_BIN: 
    case SC_OCT: case SC_DEC: 
    case SC_HEX: 
        break;
    case SC_BIN_US: case SC_BIN_SM: 
    case SC_OCT_US: case SC_OCT_SM:
    case SC_HEX_US: case SC_HEX_SM:
    case SC_CSD:
      SC_REPORT_ERROR( sc_core::SC_ID_NOT_IMPLEMENTED_,
                       "is_valid_base( sc_numrep base ) : "
                       "bases SC_CSD, or ending in _US and _SM are not supported" );
      break;
    default:
      char msg[BUFSIZ];
      std::sprintf( msg, "is_valid_base( sc_numrep base ) : "
               "base = %s is not valid",
               to_string( base ).c_str() );
      SC_REPORT_ERROR( sc_core::SC_ID_VALUE_NOT_VALID_, msg );
  }
}

// ----------------------------------------------------------------------------

// One transition of the FSM to find base and sign of a number.
extern
small_type 
fsm_move(char c, small_type &b, small_type &s, small_type &state);

// Parse a character string into its equivalent binary bits.
extern
void parse_binary_bits( 
    const char* src_p, int dst_n, sc_digit* data_p, sc_digit* ctrl_p=0
);


// Parse a character string into its equivalent hexadecimal bits.
extern
void parse_hex_bits( 
    const char* src_p, int dst_n, sc_digit* data_p, sc_digit* ctrl_p=0
);


// Find the base and sign of a number in v.
extern 
const char *
get_base_and_sign(const char *v, small_type &base, small_type &sign);

// Create a number out of v in base.
extern 
small_type 
vec_from_str(int unb, int und, sc_digit *u, 
             const char *v, sc_numrep base = SC_NOBASE) ;


// ----------------------------------------------------------------------------
//  Naming convention for the vec_ functions below:
//    vec_OP(u, v, w)  : computes w = u OP v.
//    vec_OP_on(u, v)  : computes u = u OP v if u has more digits than v.
//    vec_OP_on2(u, v) : computes u = u OP v if u has fewer digits than v.
//    _large           : parameters are vectors.
//    _small           : one of the parameters is a single digit.
//    Xlen             : the number of digits in X.
// ----------------------------------------------------------------------------

// ----------------------------------------------------------------------------
//  Functions for vector addition: w = u + v or u += v.
// ----------------------------------------------------------------------------

extern 
void 
vec_add(int ulen, const sc_digit *u, 
        int vlen, const sc_digit *v, sc_digit *w);

extern 
void 
vec_add_on(int ulen, sc_digit *u, 
           int vlen, const sc_digit *v);

extern 
void 
vec_add_on2(int ulen, sc_digit *u, 
            int vlen, const sc_digit *v);

extern 
void 
vec_add_small(int ulen, const sc_digit *u,
              sc_digit v, sc_digit *w);

extern 
void 
vec_add_small_on(int ulen, sc_digit *u, sc_digit v);


// ----------------------------------------------------------------------------
//  Functions for vector subtraction: w = u - v, u -= v, or u = v - u.
// ----------------------------------------------------------------------------

extern 
void 
vec_sub(int ulen, const sc_digit *u, 
        int vlen, const sc_digit *v, sc_digit *w);

extern 
void 
vec_sub_on(int ulen, sc_digit *u, 
           int vlen, const sc_digit *v);

extern 
void 
vec_sub_on2(int ulen, sc_digit *u,
            int vlen, const sc_digit *v);

extern 
void 
vec_sub_small(int ulen, const sc_digit *u,
              sc_digit v, sc_digit *w);

extern 
void 
vec_sub_small_on(int ulen, sc_digit *u, sc_digit v);


// ----------------------------------------------------------------------------
//  Functions for vector multiplication: w = u * v or u *= v.
// ----------------------------------------------------------------------------

extern 
void 
vec_mul(int ulen, const sc_digit *u, 
        int vlen, const sc_digit *v, sc_digit *w);

extern 
void 
vec_mul_small(int ulen, const sc_digit *u,
              sc_digit v, sc_digit *w);

extern 
void 
vec_mul_small_on(int ulen, sc_digit *u, sc_digit v);


// ----------------------------------------------------------------------------
//  Functions for vector division: w = u / v.
// ----------------------------------------------------------------------------

extern 
void 
vec_div_large(int ulen, const sc_digit *u, 
              int vlen, const sc_digit *v, sc_digit *w);

extern 
void 
vec_div_small(int ulen, const sc_digit *u, 
              sc_digit v, sc_digit *w);


// ----------------------------------------------------------------------------
//  Functions for vector remainder: w = u % v or u %= v.
// ----------------------------------------------------------------------------

extern 
void 
vec_rem_large(int ulen, const sc_digit *u, 
              int vlen, const sc_digit *v, sc_digit *w);

extern 
sc_digit 
vec_rem_small(int ulen, const sc_digit *u, sc_digit v);

extern 
sc_digit 
vec_rem_on_small(int ulen, sc_digit *u, sc_digit v);


// ----------------------------------------------------------------------------
//  Functions to convert between vectors of char and sc_digit.
// ----------------------------------------------------------------------------

extern 
int 
vec_to_char(int ulen, const sc_digit *u, 
            int vlen, uchar *v);

extern 
void 
vec_from_char(int ulen, const uchar *u,
              int vlen, sc_digit *v);


// ----------------------------------------------------------------------------
//  Functions to shift left or right, or to create a mirror image of vectors.
// ----------------------------------------------------------------------------

extern 
void 
vec_shift_left(int ulen, sc_digit *u, int nsl);

extern 
void 
vec_shift_right(int vlen, sc_digit *u, int nsr, sc_digit fill = 0);

extern
void 
vec_reverse(int unb, int und, sc_digit *ud, 
            int l, int r = 0);


// ----------------------------------------------------------------------------
//  Various utility functions. 
// ----------------------------------------------------------------------------

// Return the low half part of d.
inline 
sc_digit 
low_half(sc_digit d) 
{
  return (d & HALF_DIGIT_MASK);
}

// Return the high half part of d. The high part of the digit may have
// more bits than BITS_PER_HALF_DIGIT due to, e.g., overflow in the
// multiplication. Hence, in other functions that use high_half(),
// make sure that the result contains BITS_PER_HALF_DIGIT if
// necessary. This is done by high_half_masked().
inline 
sc_digit 
high_half(sc_digit d) 
{
  return (d >> BITS_PER_HALF_DIGIT);
}

inline
sc_digit
high_half_masked(sc_digit d)
{
  return (high_half(d) & HALF_DIGIT_MASK);
}

// Concatenate the high part h and low part l. Assumes that h and l
// are less than or equal to HALF_DIGIT_MASK;
inline 
sc_digit 
concat(sc_digit h, sc_digit l) 
{
  return ((h << BITS_PER_HALF_DIGIT) | l);
}

// Create a number with n 1's.
inline
sc_digit
one_and_ones(int n)
{
  return (((sc_digit) 1 << n) - 1);
}

// Create a number with one 1 and n 0's.
inline
sc_digit
one_and_zeros(int n)
{
  return ((sc_digit) 1 << n);
}


// ----------------------------------------------------------------------------

// Find the digit that bit i is in.
inline
int 
digit_ord(int i)
{
  return (i / BITS_PER_DIGIT);
}

// Find the bit in digit_ord(i) that bit i corressponds to.
inline
int 
bit_ord(int i)
{
  return (i % BITS_PER_DIGIT);
}


// ----------------------------------------------------------------------------
//  Functions to compare, zero, complement vector(s).
// ----------------------------------------------------------------------------

// Compare u and v and return r
//  r = 0 if u == v
//  r < 0 if u < v
//  r > 0 if u > v
// - Assume that all the leading zero digits are already skipped.
// - ulen and/or vlen can be zero.
// - Every digit is less than or equal to DIGIT_MASK;
inline 
int
vec_cmp(int ulen, const sc_digit *u, 
        int vlen, const sc_digit *v)
{

#ifdef DEBUG_SYSTEMC
  // assert((ulen <= 0) || (u != NULL));
  // assert((vlen <= 0) || (v != NULL));

  // ulen and vlen can be equal to 0 because vec_cmp can be called
  // after vec_skip_leading_zeros.
  assert((ulen >= 0) && (u != NULL));
  assert((vlen >= 0) && (v != NULL));
  // If ulen > 0, then the leading digit of u must be non-zero.
  assert((ulen <= 0) || (u[ulen - 1] != 0));
  assert((vlen <= 0) || (v[vlen - 1] != 0));
#endif

  if (ulen != vlen)
    return (ulen - vlen);

  // ulen == vlen >= 1
  while ((--ulen >= 0) && (u[ulen] == v[ulen]))
    ;

  if (ulen < 0)
    return 0;

#ifdef DEBUG_SYSTEMC
  // Test to see if the result is wrong due to the presence of
  // overflow bits.
  assert((u[ulen] & DIGIT_MASK) != (v[ulen] & DIGIT_MASK));
#endif

  return (int) (u[ulen] - v[ulen]);

}

// Find the index of the first non-zero digit.
// - ulen (before) = the number of digits in u.
// - the returned value = the index of the first non-zero digit. 
// A negative value of -1 indicates that every digit in u is zero.
inline
int
vec_find_first_nonzero(int ulen, const sc_digit *u)
{

#ifdef DEBUG_SYSTEMC
  // assert((ulen <= 0) || (u != NULL));
  assert((ulen > 0) && (u != NULL));
#endif

  while ((--ulen >= 0) && (! u[ulen]))
    ;

  return ulen;
  
}

// Skip all the leading zero digits.  
// - ulen (before) = the number of digits in u.
// - the returned value = the number of non-zero digits in u.
// - the returned value is non-negative.
inline 
int
vec_skip_leading_zeros(int ulen, const sc_digit *u)
{

#ifdef DEBUG_SYSTEMC
  // assert((ulen <= 0) || (u != NULL));
  assert((ulen > 0) && (u != NULL));
#endif

  return (1 + vec_find_first_nonzero(ulen, u));

}

// Compare u and v and return r
//  r = 0 if u == v
//  r < 0 if u < v
//  r > 0 if u > v
inline 
int 
vec_skip_and_cmp(int ulen, const sc_digit *u, 
                 int vlen, const sc_digit *v)
{

#ifdef DEBUG_SYSTEMC
  assert((ulen > 0) && (u != NULL));
  assert((vlen > 0) && (v != NULL));
#endif

  ulen = vec_skip_leading_zeros(ulen, u);
  vlen = vec_skip_leading_zeros(vlen, v);
  // ulen and/or vlen can be equal to zero here.
  return vec_cmp(ulen, u, vlen, v);

}

// Set u[i] = 0 where i = from ... (ulen - 1).
inline
void
vec_zero(int from, int ulen, sc_digit *u)
{

#ifdef DEBUG_SYSTEMC
  assert((ulen > 0) && (u != NULL));
#endif

  for(int i = from; i < ulen; i++)
    u[i] = 0;

}

// Set u[i] = 0 where i = 0 .. (ulen - 1).
inline
void
vec_zero(int ulen, sc_digit *u)
{
  vec_zero(0, ulen, u);
}

// Copy n digits from v to u.
inline
void
vec_copy(int n, sc_digit *u, const sc_digit *v)
{

#ifdef DEBUG_SYSTEMC
  assert((n > 0) && (u != NULL) && (v != NULL));
#endif

  for (int i = 0; i < n; ++i)
    u[i] = v[i];
}

// Copy v to u, where ulen >= vlen, and zero the rest of the digits in u.
inline
void
vec_copy_and_zero(int ulen, sc_digit *u, 
                  int vlen, const sc_digit *v)
{

#ifdef DEBUG_SYSTEMC
  assert((ulen > 0) && (u != NULL));
  assert((vlen > 0) && (v != NULL));
  assert(ulen >= vlen);
#endif

  vec_copy(vlen, u, v);
  vec_zero(vlen, ulen, u);

}

// 2's-complement the digits in u.
inline
void
vec_complement(int ulen, sc_digit *u)
{

#ifdef DEBUG_SYSTEMC
  assert((ulen > 0) && (u != NULL));
#endif

  sc_digit carry = 1;

  for (int i = 0; i < ulen; ++i) {
    carry += (~u[i] & DIGIT_MASK);
    u[i] = carry & DIGIT_MASK;
    carry >>= BITS_PER_DIGIT;
  }
  
}


// ----------------------------------------------------------------------------
//  Functions to handle built-in types or signs.
// ----------------------------------------------------------------------------

// u = v
// - v is an unsigned long or uint64, and positive integer.
template< class Type >
inline
void
from_uint(int ulen, sc_digit *u, Type v)
{

#ifdef DEBUG_SYSTEMC
  // assert((ulen <= 0) || (u != NULL));
  assert((ulen > 0) && (u != NULL));
  assert(v >= 0);
#endif

  int i = 0;

  while (v && (i < ulen)) {
#ifndef _WIN32
    u[i++] = static_cast<sc_digit>( v & DIGIT_MASK );
#else
    u[i++] = ((sc_digit) v) & DIGIT_MASK;
#endif
    v >>= BITS_PER_DIGIT;
  }

  vec_zero(i, ulen, u);

}


// Get u's sign and return its absolute value.
// u can be long, unsigned long, int64, or uint64.
template< class Type >
inline
small_type
get_sign(Type &u) 
{
  if (u > 0)
    return SC_POS;

  if (u == 0)
    return SC_ZERO;

  // no positive number representable for minimum value,
  // leave as is to avoid Undefined Behaviour
  if( SC_LIKELY_( u > (std::numeric_limits<Type>::min)() ) )
    u = -u;

  return SC_NEG;
}


// Return us * vs:
// - Return SC_ZERO if either sign is SC_ZERO.
// - Return SC_POS if us == vs
// - Return SC_NEG if us != vs.
inline
small_type
mul_signs(small_type us, small_type vs)
{
  if ((us == SC_ZERO) || (vs == SC_ZERO))
    return SC_ZERO;

  if (us == vs)
    return SC_POS;

  return SC_NEG;
}


// ----------------------------------------------------------------------------
//  Functions to test for errors and print out error messages.
// ----------------------------------------------------------------------------

#ifdef SC_MAX_NBITS

inline
void
test_bound(int nb)
{
  if (nb > SC_MAX_NBITS) {
      char msg[BUFSIZ];
      std::sprintf( msg, "test_bound( int nb ) : "
               "nb = %d > SC_MAX_NBITS = %d is not valid",
               nb, SC_MAX_NBITS );
      SC_REPORT_ERROR( sc_core::SC_ID_OUT_OF_BOUNDS_, msg );
  }
}

#endif

template< class Type >
inline
void
div_by_zero(Type s)
{
  if (s == 0) {
      SC_REPORT_ERROR( sc_core::SC_ID_OPERATION_FAILED_,
                       "div_by_zero<Type>( Type ) : division by zero" );
  }
}


// ----------------------------------------------------------------------------
//  Functions to check if a given vector is zero or make one.
// ----------------------------------------------------------------------------

// If u[i] is zero for every i = 0,..., ulen - 1, return SC_ZERO,
// else return s.
inline
small_type 
check_for_zero(small_type s, int ulen, const sc_digit *u)
{

#ifdef DEBUG_SYSTEMC
  // assert(ulen >= 0);
  assert((ulen > 0) && (u != NULL));
#endif

  if (vec_find_first_nonzero(ulen, u) < 0)
    return SC_ZERO;  

  return s;

}

// If u[i] is zero for every i = 0,..., ulen - 1, return true,
// else return false.
inline
bool
check_for_zero(int ulen, const sc_digit *u)
{

#ifdef DEBUG_SYSTEMC
  // assert(ulen >= 0);
  assert((ulen > 0) && (u != NULL));
#endif

  if (vec_find_first_nonzero(ulen, u) < 0)
    return true;

  return false;

}

inline
small_type
make_zero(int nd, sc_digit *d)
{
  vec_zero(nd, d);
  return SC_ZERO;
}


// ----------------------------------------------------------------------------
//  Functions for both signed and unsigned numbers to convert sign-magnitude
//  (SM) and 2's complement (2C) representations.
//  added = 1 => for signed.
//  added = 0 => for unsigned.
//  IF_SC_SIGNED can be used as 'added'.
// ----------------------------------------------------------------------------

// Trim the extra leading bits of a signed or unsigned number.
inline
void
trim(small_type added, int nb, int nd, sc_digit *d)
{
#ifdef DEBUG_SYSTEMC
  assert((nb > 0) && (nd > 0) && (d != NULL));
#endif

  d[nd - 1] &= one_and_ones(bit_ord(nb - 1) + added);    
}

// Convert an (un)signed number from sign-magnitude representation to
// 2's complement representation and trim the extra bits.
inline
void
convert_SM_to_2C_trimmed(small_type added, 
                         small_type s, int nb, int nd, sc_digit *d)
{
  if (s == SC_NEG) {
    vec_complement(nd, d);
    trim(added, nb, nd, d);
  }
}

// Convert an (un)signed number from sign-magnitude representation to
// 2's complement representation but do not trim the extra bits.
inline
void
convert_SM_to_2C(small_type s, int nd, sc_digit *d)
{
  if (s == SC_NEG)
    vec_complement(nd, d);
}


// ----------------------------------------------------------------------------
//  Functions to convert between sign-magnitude (SM) and 2's complement
//  (2C) representations of signed numbers.
// ----------------------------------------------------------------------------

// Trim the extra leading bits off a signed number.
inline
void
trim_signed(int nb, int nd, sc_digit *d)
{
#ifdef DEBUG_SYSTEMC
  assert((nb > 0) && (nd > 0) && (d != NULL));
#endif

  d[nd - 1] &= one_and_ones(bit_ord(nb - 1) + 1);
}

// Convert a signed number from 2's complement representation to
// sign-magnitude representation, and return its sign. nd is d's
// actual size, without zeros eliminated.
inline
small_type
convert_signed_2C_to_SM(int nb, int nd, sc_digit *d)
{

#ifdef DEBUG_SYSTEMC
  assert((nb > 0) && (nd > 0) && (d != NULL));
#endif

  small_type s;

  int xnb = bit_ord(nb - 1) + 1;

  // Test the sign bit.  
  if (d[nd - 1] & one_and_zeros(xnb - 1)) {
    s = SC_NEG;
    vec_complement(nd, d);
  }
  else
    s = SC_POS;

  // Trim the last digit.
  d[nd - 1] &= one_and_ones(xnb);

  // Check if the new number is zero.
  if (s == SC_POS)
    return check_for_zero(s, nd, d);

  return s;

}

// Convert a signed number from sign-magnitude representation to 2's
// complement representation, get its sign, convert back to
// sign-magnitude representation, and return its sign. nd is d's
// actual size, without zeros eliminated.
inline
small_type 
convert_signed_SM_to_2C_to_SM(small_type s, int nb, int nd, sc_digit *d)
{
  convert_SM_to_2C(s, nd, d);
  return convert_signed_2C_to_SM(nb, nd, d);
}

// Convert a signed number from sign-magnitude representation to 2's
// complement representation and trim the extra bits.
inline
void
convert_signed_SM_to_2C_trimmed(small_type s, int nb, int nd, sc_digit *d)
{
  convert_SM_to_2C_trimmed(1, s, nb, nd, d);
}

// Convert a signed number from sign-magnitude representation to 2's
// complement representation but do not trim the extra bits.
inline
void
convert_signed_SM_to_2C(small_type s, int nd, sc_digit *d)
{
  convert_SM_to_2C(s, nd, d);
}


// ----------------------------------------------------------------------------
//  Functions to convert between sign-magnitude (SM) and 2's complement
//  (2C) representations of unsigned numbers.
// ----------------------------------------------------------------------------

// Trim the extra leading bits off an unsigned number.
inline
void
trim_unsigned(int nb, int nd, sc_digit *d)
{
#ifdef DEBUG_SYSTEMC
  assert((nb > 0) && (nd > 0) && (d != NULL));
#endif

  d[nd - 1] &= one_and_ones(bit_ord(nb - 1));    
}

// Convert an unsigned number from 2's complement representation to
// sign-magnitude representation, and return its sign. nd is d's
// actual size, without zeros eliminated.
inline
small_type
convert_unsigned_2C_to_SM(int nb, int nd, sc_digit *d)
{
  trim_unsigned(nb, nd, d);
  return check_for_zero(SC_POS, nd, d);
}

// Convert an unsigned number from sign-magnitude representation to
// 2's complement representation, get its sign, convert back to
// sign-magnitude representation, and return its sign. nd is d's
// actual size, without zeros eliminated.
inline
small_type
convert_unsigned_SM_to_2C_to_SM(small_type s, int nb, int nd, sc_digit *d)
{
  convert_SM_to_2C(s, nd, d);
  return convert_unsigned_2C_to_SM(nb, nd, d);
}

// Convert an unsigned number from sign-magnitude representation to
// 2's complement representation and trim the extra bits.
inline
void
convert_unsigned_SM_to_2C_trimmed(small_type s, int nb, int nd, sc_digit *d)
{
  convert_SM_to_2C_trimmed(0, s, nb, nd, d);
}

// Convert an unsigned number from sign-magnitude representation to
// 2's complement representation but do not trim the extra bits.
inline
void
convert_unsigned_SM_to_2C(small_type s, int nd, sc_digit *d)
{
  convert_SM_to_2C(s, nd, d);
}


// ----------------------------------------------------------------------------
//  Functions to copy one (un)signed number to another.
// ----------------------------------------------------------------------------

// Copy v to u.
inline
void
copy_digits_signed(small_type &us, 
                   int unb, int und, sc_digit *ud,
                   int vnb, int vnd, const sc_digit *vd)
{

  if (und <= vnd) {

    vec_copy(und, ud, vd);

    if (unb <= vnb)
      us = convert_signed_SM_to_2C_to_SM(us, unb, und, ud);

  }
  else // und > vnd
    vec_copy_and_zero(und, ud, vnd, vd);

}

// Copy v to u.
inline
void
copy_digits_unsigned(small_type &us, 
                     int unb, int und, sc_digit *ud,
                     int /* vnb */, int vnd, const sc_digit *vd)
{

  if (und <= vnd)
    vec_copy(und, ud, vd);

  else // und > vnd
    vec_copy_and_zero(und, ud, vnd, vd);

  us = convert_unsigned_SM_to_2C_to_SM(us, unb, und, ud);

}


// ----------------------------------------------------------------------------
//  Faster set(i, v), without bound checking.
// ----------------------------------------------------------------------------

// A version of set(i, v) without bound checking.
inline
void
safe_set(int i, bool v, sc_digit *d)
{

#ifdef DEBUG_SYSTEMC
  assert((i >= 0) && (d != NULL));
#endif

  int bit_num = bit_ord(i);
  int digit_num = digit_ord(i);    
  
  if (v)
    d[digit_num] |= one_and_zeros(bit_num);      
  else
    d[digit_num] &= ~(one_and_zeros(bit_num));
  
}


// ----------------------------------------------------------------------------
//  Function to check if a double number is bad (NaN or infinite).
// ----------------------------------------------------------------------------

inline
bool
is_nan( double v )
{
    return std::numeric_limits<double>::has_quiet_NaN && (v != v);
}

inline
bool
is_inf( double v )
{
    return v ==  std::numeric_limits<double>::infinity()
        || v == -std::numeric_limits<double>::infinity();
}

inline
void
is_bad_double(double v)
{
// Windows throws exception.
    if( is_nan(v) || is_inf(v) )
        SC_REPORT_ERROR( sc_core::SC_ID_VALUE_NOT_VALID_,
                         "is_bad_double( double v ) : "
                         "v is not finite - NaN or Inf" );
}

} // namespace sc_dt


#endif