sc_nbexterns.cpp

system C源码 一种替代verilog的语言

    if (cmp_res == 0) { 
      us = SC_ZERO;
      vec_zero(old_und, ud);
      return;
    }
    
    // else if u > v - case 5
    
    sc_digit vd0 = (*vd);
    
    if ((vnd == 1) && (vd0 == 1)) {
      us = SC_ZERO;
      vec_zero(old_und, ud);
      return;
    }
    
    // One extra digit for d is allocated to simplify vec_div_*().
    int nd = sc_max(und, vnd) + 1;
    
#ifdef SC_MAX_NBITS
    sc_digit d[MAX_NDIGITS + 1];
#else
    sc_digit *d = new sc_digit[nd];
#endif
    
    vec_zero(nd, d);
    
    if ((vnd == 1) && (und == 1))
      d[0] = (*ud) % vd0;
    
    if ((vnd == 1) && (vd0 < HALF_DIGIT_RADIX))
      d[0] = vec_rem_small(und, ud, vd0);
    
    else
      vec_rem_large(und, ud, vnd, vd, d);
    
    us = check_for_zero(us, nd - 1, d);
    
    if (us == SC_ZERO)
      vec_zero(old_und, ud);
    else
      COPY_DIGITS(us, unb, old_und, ud, sc_min(unb, vnd), nd - 1, d);
    
#ifndef SC_MAX_NBITS
    delete [] d;
#endif
    
  }
  
#undef COPY_DIGITS
  
}


void
mod_on_help_unsigned(small_type &us, 
                     int unb, int und, 
                     sc_digit *ud, 
                     int /* vnb */, int vnd,
                     const sc_digit *vd)
{

#define COPY_DIGITS copy_digits_unsigned

  { // Body of mod_on_help

    int old_und = und;
    
    und = vec_skip_leading_zeros(und, ud);
    vnd = vec_skip_leading_zeros(vnd, vd);
    
    int cmp_res = vec_cmp(und, ud, vnd, vd);
    
    // u < v => u % v = u - case 4
    if (cmp_res < 0) 
      return;
    
    // u = v => u % v = 0 - case 3
    if (cmp_res == 0) { 
      us = SC_ZERO;
      vec_zero(old_und, ud);
      return;
    }
    
    // else if u > v - case 5
    
    sc_digit vd0 = (*vd);
    
    if ((vnd == 1) && (vd0 == 1)) {
      us = SC_ZERO;
      vec_zero(old_und, ud);
      return;
    }
    
    // One extra digit for d is allocated to simplify vec_div_*().
    int nd = sc_max(und, vnd) + 1;
    
#ifdef SC_MAX_NBITS
    sc_digit d[MAX_NDIGITS + 1];
#else
    sc_digit *d = new sc_digit[nd];
#endif
    
    vec_zero(nd, d);
    
    if ((vnd == 1) && (und == 1))
      d[0] = (*ud) % vd0;
    
    if ((vnd == 1) && (vd0 < HALF_DIGIT_RADIX))
      d[0] = vec_rem_small(und, ud, vd0);
    
    else
      vec_rem_large(und, ud, vnd, vd, d);
    
    us = check_for_zero(us, nd - 1, d);
    
    if (us == SC_ZERO)
      vec_zero(old_und, ud);
    else
      COPY_DIGITS(us, unb, old_und, ud, sc_min(unb, vnd), nd - 1, d);
    
#ifndef SC_MAX_NBITS
    delete [] d;
#endif
    
  }
  
#undef COPY_DIGITS
  
}


// ----------------------------------------------------------------------------
//  SECTION: External functions for AND operators.
// ----------------------------------------------------------------------------

// Handles the cases 2-5 and returns the result in u.
void
and_on_help(small_type us, 
            int /* unb */, int und, 
            sc_digit *ud, 
            small_type vs,
            int /* vnb */, int vnd,
            const sc_digit *vd)
{

  register sc_digit *x = ud;
  register const sc_digit *y = vd;
  int xnd = und;
  int ynd = vnd;

  // Truncate y.
  if (xnd < ynd)
    ynd = xnd;

  const sc_digit *xend = (x + xnd);
  const sc_digit *yend = (y + ynd);

  // x is longer than y.

  small_type s = mul_signs(us, vs);

  if (s > 0) {

    if (us > 0) { // case 2

      while (y < yend)
        (*x++) &= (*y++);

      while (x < xend)
        (*x++) = 0;

    }
    else {  // case 3

      register sc_digit xcarry = 1;
      register sc_digit ycarry = 1;

      while (y < yend) {
        xcarry += (~(*x) & DIGIT_MASK);
        ycarry += (~(*y++) & DIGIT_MASK);
        (*x++) = (xcarry & ycarry) & DIGIT_MASK;
        xcarry >>= BITS_PER_DIGIT;
        ycarry >>= BITS_PER_DIGIT;
      }

      while (x < xend) {
        xcarry += (~(*x) & DIGIT_MASK);
        ycarry += DIGIT_MASK;
        (*x++) = (xcarry & ycarry) & DIGIT_MASK;
        xcarry >>= BITS_PER_DIGIT;
        ycarry >>= BITS_PER_DIGIT;
      }

    }
  }
  else {

    if (us > 0) { // case 4

      register sc_digit ycarry = 1;

      while (y < yend) {
        ycarry += (~(*y++) & DIGIT_MASK);
        (*x++) &= ycarry & DIGIT_MASK;
        ycarry >>= BITS_PER_DIGIT;
      }

      while (x < xend) {
        ycarry += DIGIT_MASK;
        (*x++) &= ycarry & DIGIT_MASK;
        ycarry >>= BITS_PER_DIGIT;
      }

    }
    else {  // case 5

      register sc_digit xcarry = 1;

      while (y < yend) {
        xcarry += (~(*x) & DIGIT_MASK);
        (*x++) = (xcarry & (*y++)) & DIGIT_MASK;
        xcarry >>= BITS_PER_DIGIT;
      }

      while (x < xend)
        (*x++) = 0;

    }
  }
}


// ----------------------------------------------------------------------------
//  SECTION: External functions for OR operators.
// ----------------------------------------------------------------------------

// Handles the cases 3-5 and returns the result in u.
void
or_on_help(small_type us, 
           int /* unb */, int und, 
           sc_digit *ud, 
           small_type vs,
           int /* vnb */, int vnd,
           const sc_digit *vd)
{
  
  register sc_digit *x = ud;
  register const sc_digit *y = vd;
  int xnd = und;
  int ynd = vnd;

  if (xnd < ynd)
    ynd = xnd;

  const sc_digit *xend = (x + xnd);
  const sc_digit *yend = (y + ynd);

  // x is longer than y.

  small_type s = mul_signs(us, vs);

  if (s > 0) {

    if (us > 0) { // case 3

      while (y < yend)
        (*x++) |= (*y++);

      // No change for the rest of x.

    }
    else {  // case 4

      register sc_digit xcarry = 1;
      register sc_digit ycarry = 1;

      while (y < yend) {
        xcarry += (~(*x) & DIGIT_MASK);
        ycarry += (~(*y++) & DIGIT_MASK);
        (*x++) = (xcarry | ycarry) & DIGIT_MASK;
        xcarry >>= BITS_PER_DIGIT;
        ycarry >>= BITS_PER_DIGIT;
      }

      while (x < xend) {
        xcarry += (~(*x) & DIGIT_MASK);
        ycarry += DIGIT_MASK;
        (*x++) = (xcarry | ycarry) & DIGIT_MASK;
        xcarry >>= BITS_PER_DIGIT;
        ycarry >>= BITS_PER_DIGIT;
      }
    }

  }
  else {

    if (us > 0) { // case 5

      register sc_digit ycarry = 1;

      while (y < yend) {
        ycarry += (~(*y++) & DIGIT_MASK);
        (*x) = ((*x) | ycarry) & DIGIT_MASK;
        x++;
        ycarry >>= BITS_PER_DIGIT;
      }

      while (x < xend) {
        ycarry += DIGIT_MASK;
        (*x) = ((*x) | ycarry) & DIGIT_MASK;
        x++;
        ycarry >>= BITS_PER_DIGIT;
      }

    }
    else {  // case 6

      register sc_digit xcarry = 1;

      while (y < yend) {
        xcarry += (~(*x) & DIGIT_MASK);
        (*x++) = (xcarry | (*y++)) & DIGIT_MASK;
        xcarry >>= BITS_PER_DIGIT;
      }

      while (x < xend) {
        xcarry += (~(*x) & DIGIT_MASK);
        (*x++) = xcarry & DIGIT_MASK;
        xcarry >>= BITS_PER_DIGIT;
      }
    }
  }
}


// ----------------------------------------------------------------------------
//  SECTION: External functions for XOR operators.
// ----------------------------------------------------------------------------

// Handles the cases 3-5 and returns the result in u.
void
xor_on_help(small_type us, 
            int /* unb */, int und, 
            sc_digit *ud, 
            small_type vs,
            int /* vnb */, int vnd,
            const sc_digit *vd)
{
  
  register sc_digit *x = ud;
  register const sc_digit *y = vd;
  int xnd = und;
  int ynd = vnd;

  if (xnd < ynd)
    ynd = xnd;

  const sc_digit *xend = (x + xnd);
  const sc_digit *yend = (y + ynd);

  // x is longer than y.

  small_type s = mul_signs(us, vs);

  if (s > 0) {

    if (us > 0) { // case 3

      while (y < yend) {
        (*x) = ((*x) ^ (*y)) & DIGIT_MASK;
        x++;
        y++;
      }

      // No change for the rest of x.

    }
    else {  // case 4

      register sc_digit xcarry = 1;
      register sc_digit ycarry = 1;

      while (y < yend) {
        xcarry += (~(*x) & DIGIT_MASK);
        ycarry += (~(*y++) & DIGIT_MASK);
        (*x++) = (xcarry ^ ycarry) & DIGIT_MASK;
        xcarry >>= BITS_PER_DIGIT;
        ycarry >>= BITS_PER_DIGIT;
      }

      while (x < xend) {
        xcarry += (~(*x) & DIGIT_MASK);
        ycarry += DIGIT_MASK;
        (*x++) = (xcarry ^ ycarry) & DIGIT_MASK;
        xcarry >>= BITS_PER_DIGIT;
        ycarry >>= BITS_PER_DIGIT;
      }
    }
  }
  else {

    if (us > 0) { // case 5

      register sc_digit ycarry = 1;

      while (y < yend) {
        ycarry += (~(*y++) & DIGIT_MASK);
        (*x) = ((*x) ^ ycarry) & DIGIT_MASK;
        x++;
        ycarry >>= BITS_PER_DIGIT;
      }

      while (x < xend) {
        ycarry += DIGIT_MASK;
        (*x) = ((*x) ^ ycarry) & DIGIT_MASK;
        x++;
        ycarry >>= BITS_PER_DIGIT;
      }

    }
    else {  // case 6

      register sc_digit xcarry = 1;

      while (y < yend) {
        xcarry += (~(*x) & DIGIT_MASK);
        (*x++) = (xcarry ^ (*y++)) & DIGIT_MASK;
        xcarry >>= BITS_PER_DIGIT;
      }

      while (x < xend) {
        xcarry += (~(*x) & DIGIT_MASK);
        (*x++) = xcarry & DIGIT_MASK;
        xcarry >>= BITS_PER_DIGIT;
      }
    }
  }
}

} // namespace sc_dt


// End of file