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Make the add func resilient to bit widths (PR#141)

This commit is contained in:
steve 2001-02-10 01:57:18 +00:00
parent 2b903f5d0e
commit 563065053e
1 changed files with 29 additions and 4 deletions
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33
vvm/vvm_func.cc
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@ -17,7 +17,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#if !defined(WINNT) && !defined(macintosh)
#ident "$Id: vvm_func.cc,v 1.14 2001/02/07 21:47:13 steve Exp $"
#ident "$Id: vvm_func.cc,v 1.15 2001/02/10 01:57:18 steve Exp $"
#endif
# include "vvm_func.h"
@ -136,13 +136,35 @@ void vvm_binop_or(vvm_bitset_t&v, const vvm_bitset_t&l, const vvm_bitset_t&r)
v[idx] = B_OR(l[idx], r[idx]);
}
/*
* This function adds two vectors to make a result vector. The
* operands and the result have their sizes already determined, so we
* take those into account.
*/
void vvm_binop_plus(vvm_bitset_t&v, const vvm_bitset_t&l, const vvm_bitset_t&r)
{
assert(v.nbits == l.nbits);
assert(v.nbits == r.nbits);
vpip_bit_t carry = St0;
for (unsigned idx = 0 ; idx < v.nbits ; idx += 1)
unsigned top = v.nbits;
if (l.nbits < top)
top = l.nbits;
if (r.nbits < top)
top = r.nbits;
unsigned idx;
/* First do the addition for the part of the vector where we
know that the bits from both inputs are present. */
for (idx = 0 ; idx < top ; idx += 1)
v[idx] = add_with_carry(l[idx], r[idx], carry);
/* Now continue the addition, padding the shorter vector with
St0 until we fill the result vector. */
for ( ; idx < v.nbits ; idx += 1) {
vpip_bit_t lv = (idx < l.nbits) ? l[idx] : St0;
vpip_bit_t rv = (idx < r.nbits) ? r[idx] : St0;
v[idx] = add_with_carry(lv, rv, carry);
}
}
void vvm_binop_shiftl(vvm_bitset_t&v,
@ -607,6 +629,9 @@ void vvm_ternary(vvm_bitset_t&v, vpip_bit_t c,
/*
* $Log: vvm_func.cc,v $
* Revision 1.15 2001/02/10 01:57:18 steve
* Make the add func resilient to bit widths (PR#141)
*
* Revision 1.14 2001/02/07 21:47:13 steve
* Fix expression widths for rvalues and parameters (PR#131,132)
*