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Simpler implementation of multiplication.

This commit is contained in:
steve 2000-03-04 01:13:54 +00:00
parent aae17041ef
commit 380d5620e6
1 changed files with 47 additions and 12 deletions
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59
vvm/vvm_mult.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_mult.cc,v 1.2 2000/02/23 02:56:57 steve Exp $"
#ident "$Id: vvm_mult.cc,v 1.3 2000/03/04 01:13:54 steve Exp $"
#endif
# include "vvm_gates.h"
@ -27,20 +27,52 @@ void vvm_binop_mult(vpip_bit_t*r, unsigned nr,
const vpip_bit_t*a, unsigned na,
const vpip_bit_t*b, unsigned nb)
{
assert(nr >= (na+nb));
assert(nr <= 8*sizeof(unsigned long));
assert(na <= 8*sizeof(unsigned long));
assert(nb <= 8*sizeof(unsigned long));
for (unsigned idx = 0 ; idx < nr ; idx += 1)
r[idx] = V0;
unsigned long av = 0, bv = 0;
unsigned long rv;
for (unsigned bdx = 0 ; bdx < nb ; bdx += 1) {
unsigned rdx = bdx;
vpip_bit_t c = V0;
for (unsigned idx = 0 ; idx < na ; idx += 1) {
r[rdx] = add_with_carry(r[rdx],a[idx]&b[bdx],c);
rdx += 1;
}
if (rdx < nr) r[rdx] = add_with_carry(r[rdx],c,c);
for (unsigned idx = 0 ; idx < na ; idx += 1) switch (a[idx]) {
case V0:
break;
case V1:
av |= 1 << idx;
break;
default:
goto unknown_result;
}
for (unsigned idx = 0 ; idx < nb ; idx += 1) switch (b[idx]) {
case V0:
break;
case V1:
bv |= 1 << idx;
break;
default:
goto unknown_result;
}
rv = av * bv;
for (unsigned idx = 0 ; idx < nr ; idx += 1) {
if (rv & 1)
r[idx] = V1;
else
r[idx] = V0;
rv >>= 1;
}
return;
unknown_result:
for (unsigned idx= 0 ; idx < nr ; idx += 1)
r[idx] = Vx;
}
vvm_mult::vvm_mult(unsigned rwid, unsigned awid,
@ -107,6 +139,9 @@ void vvm_mult::set_DataB(unsigned idx, vpip_bit_t val)
/*
* $Log: vvm_mult.cc,v $
* Revision 1.3 2000/03/04 01:13:54 steve
* Simpler implementation of multiplication.
*
* Revision 1.2 2000/02/23 02:56:57 steve
* Macintosh compilers do not support ident.
*