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Remove width restriction on subtraction.

This commit is contained in:
steve 2001-07-13 00:38:57 +00:00
parent 3154f07817
commit 15a952a143
2 changed files with 69 additions and 16 deletions
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76
vvp/arith.cc
View File

@ -17,14 +17,15 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/ */
#if !defined(WINNT) #if !defined(WINNT)
#ident "$Id: arith.cc,v 1.10 2001/07/11 02:27:21 steve Exp $" #ident "$Id: arith.cc,v 1.11 2001/07/13 00:38:57 steve Exp $"
#endif #endif
# include "arith.h" # include "arith.h"
# include "schedule.h" # include "schedule.h"
# include <limits.h>
# include <assert.h> # include <assert.h>
# include <stdio.h>
vvp_arith_::vvp_arith_(vvp_ipoint_t b, unsigned w) vvp_arith_::vvp_arith_(vvp_ipoint_t b, unsigned w)
: base_(b), wid_(w) : base_(b), wid_(w)
@ -138,6 +139,7 @@ void vvp_arith_sum::set(vvp_ipoint_t i, functor_t f, bool push)
tmp += 1; tmp += 1;
// Add in the carry carried over. // Add in the carry carried over.
assert(tmp < (ULONG_MAX/2));
tmp += carry; tmp += carry;
// Put the next bit into the sum, // Put the next bit into the sum,
sum_[page] |= ((tmp&1) << pbit); sum_[page] |= ((tmp&1) << pbit);
@ -181,13 +183,31 @@ void vvp_arith_sum::set(vvp_ipoint_t i, functor_t f, bool push)
vvp_arith_sub::vvp_arith_sub(vvp_ipoint_t b, unsigned w) vvp_arith_sub::vvp_arith_sub(vvp_ipoint_t b, unsigned w)
: vvp_arith_(b, w) : vvp_arith_(b, w)
{ {
sum_ = new unsigned long[(w+1) / 8*sizeof(unsigned long) + 1];
} }
vvp_arith_sub::~vvp_arith_sub()
{
delete[]sum_;
}
/*
* Subtraction works by adding the 2s complement of the B, C and D
* inputs from the A input. The 2s complement is the 1s complement
* plus one, so we further reduce the operation to adding in the
* inverted value and adding a correction.
*/
void vvp_arith_sub::set(vvp_ipoint_t i, functor_t f, bool push) void vvp_arith_sub::set(vvp_ipoint_t i, functor_t f, bool push)
{ {
assert(wid_ <= 8*sizeof(unsigned long)); unsigned page = 0;
unsigned pbit = 0;
unsigned long sum = 0; /* There are 3 values subtracted from the first parameter, so
there are three 2s complements, so three ~X +1. That's why
the carry starts with 3. */
unsigned long carry = 3;
sum_[0] = 0;
for (unsigned idx = 0 ; idx < wid_ ; idx += 1) { for (unsigned idx = 0 ; idx < wid_ ; idx += 1) {
vvp_ipoint_t ptr = ipoint_index(base_,idx); vvp_ipoint_t ptr = ipoint_index(base_,idx);
@ -199,25 +219,47 @@ void vvp_arith_sub::set(vvp_ipoint_t i, functor_t f, bool push)
return; return;
} }
unsigned tmp = 0; // Accumulate the sum of the input bits. Add in the
// first value, and the ones complement of the other values.
unsigned long tmp = 0;
if (ival & 0x01) if (ival & 0x01)
tmp += 1; tmp += 1;
if (ival & 0x04) if (! (ival & 0x04))
tmp -= 1; tmp += 1;
if (ival & 0x10) if (! (ival & 0x10))
tmp -= 1; tmp += 1;
if (ival & 0x40) if (! (ival & 0x40))
tmp -= 1; tmp += 1;
sum += (tmp << idx); // Add in the carry carried over.
assert(tmp < (ULONG_MAX/2));
tmp += carry;
// Put the next bit into the sum,
sum_[page] |= ((tmp&1) << pbit);
// ... and carry the remaining bits.
carry = tmp >> 1;
pbit += 1;
if (pbit == 8 * sizeof sum_[page]) {
pbit = 0;
page += 1;
sum_[page] = 0;
}
} }
page = 0;
pbit = 0;
for (unsigned idx = 0 ; idx < wid_ ; idx += 1) { for (unsigned idx = 0 ; idx < wid_ ; idx += 1) {
vvp_ipoint_t ptr = ipoint_index(base_,idx); vvp_ipoint_t ptr = ipoint_index(base_,idx);
functor_t obj = functor_index(ptr); functor_t obj = functor_index(ptr);
unsigned oval = sum & 1; unsigned oval = (sum_[page] >> pbit) & 1;
sum >>= 1;
pbit += 1;
if (pbit == 8 * sizeof sum_[page]) {
pbit = 0;
page += 1;
}
if (obj->oval == oval) if (obj->oval == oval)
continue; continue;
@ -229,6 +271,7 @@ void vvp_arith_sub::set(vvp_ipoint_t i, functor_t f, bool push)
else else
schedule_functor(ptr, 0); schedule_functor(ptr, 0);
} }
} }
vvp_cmp_ge::vvp_cmp_ge(vvp_ipoint_t b, unsigned w) vvp_cmp_ge::vvp_cmp_ge(vvp_ipoint_t b, unsigned w)
@ -466,6 +509,9 @@ void vvp_shiftr::set(vvp_ipoint_t i, functor_t f, bool push)
/* /*
* $Log: arith.cc,v $ * $Log: arith.cc,v $
* Revision 1.11 2001/07/13 00:38:57 steve
* Remove width restriction on subtraction.
*
* Revision 1.10 2001/07/11 02:27:21 steve * Revision 1.10 2001/07/11 02:27:21 steve
* Add support for REadOnlySync and monitors. * Add support for REadOnlySync and monitors.
* *

9
vvp/arith.h
View File

@ -19,7 +19,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/ */
#if !defined(WINNT) #if !defined(WINNT)
#ident "$Id: arith.h,v 1.7 2001/07/07 02:57:33 steve Exp $" #ident "$Id: arith.h,v 1.8 2001/07/13 00:38:57 steve Exp $"
#endif #endif
# include "functor.h" # include "functor.h"
@ -79,9 +79,13 @@ class vvp_arith_sub : public vvp_arith_ {
public: public:
explicit vvp_arith_sub(vvp_ipoint_t b, unsigned wid); explicit vvp_arith_sub(vvp_ipoint_t b, unsigned wid);
virtual ~vvp_arith_sub();
void set(vvp_ipoint_t i, functor_t f, bool push); void set(vvp_ipoint_t i, functor_t f, bool push);
private:
unsigned long*sum_;
private: // not implemented private: // not implemented
vvp_arith_sub(const vvp_arith_sub&); vvp_arith_sub(const vvp_arith_sub&);
vvp_arith_sub& operator= (const vvp_arith_sub&); vvp_arith_sub& operator= (const vvp_arith_sub&);
@ -143,6 +147,9 @@ class vvp_shiftr : public vvp_arith_ {
/* /*
* $Log: arith.h,v $ * $Log: arith.h,v $
* Revision 1.8 2001/07/13 00:38:57 steve
* Remove width restriction on subtraction.
*
* Revision 1.7 2001/07/07 02:57:33 steve * Revision 1.7 2001/07/07 02:57:33 steve
* Add the .shift/r functor. * Add the .shift/r functor.
* *