luke
/
iverilog
mirror of https://github.com/steveicarus/iverilog.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Regularize padding of signed constants 

Factor common code for processing signed constants to be padded.
In the process, fix some minor bugs in the padding decisions.

Signed-off-by: Stephen Williams <steve@icarus.com>
This commit is contained in:
Stephen Williams 2007-10-15 20:17:06 -07:00
parent 7bba276a79
commit 27b704b054
2 changed files with 5 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
elab_net.cc
View File

@ -2620,25 +2620,9 @@ NetNet* PENumber::elaborate_net(Design*des, NetScope*scope,
net->local_flag(true); net->local_flag(true);
net->set_signed(value_->has_sign()); net->set_signed(value_->has_sign());
/* when expanding a constant to fit into the net, extend verinum num = pad_to_width(*value_, lwidth);
the Vx or Vz values if they are in the sign position, if (num.len() > lwidth)
otherwise extend the number with 0 bits. */ num = verinum(num, lwidth);
verinum::V top_v = verinum::V0;
switch (value_->get(value_->len()-1)) {
case verinum::Vx:
top_v = verinum::Vx;
break;
case verinum::Vz:
top_v = verinum::Vz;
break;
default: /* V0 and V1, do nothing */
break;
}
verinum num(top_v, net->vector_width());
unsigned idx;
for (idx = 0 ; idx < num.len() && idx < value_->len(); idx += 1)
num.set(idx, value_->get(idx));
NetConst*tmp = new NetConst(scope, scope->local_symbol(), num); NetConst*tmp = new NetConst(scope, scope->local_symbol(), num);
tmp->pin(0).drive0(drive0); tmp->pin(0).drive0(drive0);

14
pad_to_width.cc
View File

@ -25,6 +25,7 @@
# include "netlist.h" # include "netlist.h"
# include "netmisc.h" # include "netmisc.h"
/* /*
* This function transforms an expression by padding the high bits * This function transforms an expression by padding the high bits
* with V0 until the expression has the desired width. This may mean * with V0 until the expression has the desired width. This may mean
@ -39,18 +40,7 @@ NetExpr*pad_to_width(NetExpr*expr, unsigned wid)
/* If the expression is a const, then replace it with a wider /* If the expression is a const, then replace it with a wider
const. This is a more efficient result. */ const. This is a more efficient result. */
if (NetEConst*tmp = dynamic_cast<NetEConst*>(expr)) { if (NetEConst*tmp = dynamic_cast<NetEConst*>(expr)) {
verinum eval = tmp->value(); verinum oval = pad_to_width(tmp->value(), wid);
bool signed_flag = eval.has_sign();
verinum::V pad = verinum::V0;
if (signed_flag)
pad = eval.get(eval.len()-1);
verinum oval (pad, wid, eval.has_len());
for (unsigned idx = 0 ; idx < eval.len() ; idx += 1)
oval.set(idx, eval.get(idx));
oval.has_sign(signed_flag);
tmp = new NetEConst(oval); tmp = new NetEConst(oval);
delete expr; delete expr;
return tmp; return tmp;