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Support bit selects of non-0 lsb for vectors.

This commit is contained in:
steve 2001-10-23 04:22:41 +00:00
parent 2adea8de48
commit b1f1f74920
1 changed files with 52 additions and 3 deletions
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55
t-dll-expr.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: t-dll-expr.cc,v 1.19 2001/10/19 21:53:24 steve Exp $"
#ident "$Id: t-dll-expr.cc,v 1.20 2001/10/23 04:22:41 steve Exp $"
#endif
# include "config.h"
@ -237,9 +237,9 @@ void dll_target::expr_subsignal(const NetEBitSel*net)
ivl_expr_t expr = (ivl_expr_t)calloc(1, sizeof(struct ivl_expr_s));
assert(expr);
if (0/*net->sig()->lsb() != 0*/) {
if (net->sig()->lsb() > net->sig()->msb() ) {
cerr << net->get_line() << ": sorry: LSB for signal "
<< "is not zero." << endl;
<< "is > MSB." << endl;
}
expr->type_ = IVL_EX_BITSEL;
@ -251,6 +251,52 @@ void dll_target::expr_subsignal(const NetEBitSel*net)
assert(expr_);
expr->u_.bitsel_.bit = expr_;
/* If the lsb of the signal is not 0, then we are about to
lose the proper offset to the normalized vector. Modify the
expression to subtract the offset:
reg [7:4] a;
... = a[x];
becomes
reg [3:0] a;
... = a[x-4];
to reflect the normalizing of vectors that is done by the
compiler. */
if (net->sig()->lsb() != 0) {
/* Create in tmpc the constant offset (4 in the above
example) to be subtracted from the index. */
char*bits;
long lsb = net->sig()->lsb();
ivl_expr_t tmpc = (ivl_expr_t)calloc(1, sizeof(struct ivl_expr_s));
tmpc->type_ = IVL_EX_NUMBER;
tmpc->width_ = expr->u_.bitsel_.bit->width_;
tmpc->signed_ = net->index()->has_sign()? 1 : 0;
tmpc->u_.number_.bits_ = bits = (char*)malloc(tmpc->width_);
for (unsigned idx = 0 ; idx < tmpc->width_ ; idx += 1) {
bits[idx] = (lsb & 1)? '1' : '0';
lsb >>= 1;
}
/* Now make the subtractor (x-4 in the above example)
that has as input A the index expression and input B
the constant to subtract. */
ivl_expr_t tmps = (ivl_expr_t)calloc(1, sizeof(struct ivl_expr_s));
tmps->type_ = IVL_EX_BINARY;
tmps->width_ = tmpc->width_;
tmps->signed_ = net->index()->has_sign()? 1 : 0;
tmps->u_.binary_.op_ = '-';
tmps->u_.binary_.lef_ = expr->u_.bitsel_.bit;
tmps->u_.binary_.rig_ = tmpc;
/* Replace (x) with (x-4) */
expr->u_.bitsel_.bit = tmps;
}
expr_ = expr;
}
@ -301,6 +347,9 @@ void dll_target::expr_unary(const NetEUnary*net)
/*
* $Log: t-dll-expr.cc,v $
* Revision 1.20 2001/10/23 04:22:41 steve
* Support bit selects of non-0 lsb for vectors.
*
* Revision 1.19 2001/10/19 21:53:24 steve
* Support multiple root modules (Philip Blundell)
*