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Fix continuous assignment of constants 

E.g. in assign p = 1 the RHS signal in the generated LPM now
has a correct intial value (and it will never be written to
elsewhere)
This commit is contained in:
Nick Gasson 2008-07-03 15:13:12 +01:00
parent 4fac825457
commit 7e999c5496
1 changed files with 42 additions and 3 deletions
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45
tgt-vhdl/scope.cc
View File

@ -27,6 +27,32 @@
static vhdl_expr *translate_logic(vhdl_scope *scope, ivl_net_logic_t log);
/*
* Given a nexus find a constant value in it that can be used
* as an initial signal value.
*/
static vhdl_expr *nexus_to_const(ivl_nexus_t nexus)
{
int nptrs = ivl_nexus_ptrs(nexus);
for (int i = 0; i < nptrs; i++) {
ivl_nexus_ptr_t nexus_ptr = ivl_nexus_ptr(nexus, i);
ivl_net_const_t con;
if ((con = ivl_nexus_ptr_con(nexus_ptr))) {
if (ivl_const_width(con) == 1)
return new vhdl_const_bit(ivl_const_bits(con)[0]);
else
return new vhdl_const_bits
(ivl_const_bits(con), ivl_const_width(con),
ivl_const_signed(con) != 0);
}
else {
// Ignore other types of nexus pointer
}
}
return NULL;
}
/*
* Given a nexus and an architecture scope, find the first signal
@ -202,7 +228,18 @@ static void declare_signals(vhdl_entity *ent, ivl_scope_t scope)
ivl_signal_port_t mode = ivl_signal_port(sig);
switch (mode) {
case IVL_SIP_NONE:
ent->get_arch()->get_scope()->add_decl(new vhdl_signal_decl(name.c_str(), sig_type));
{
vhdl_decl *decl = new vhdl_signal_decl(name.c_str(), sig_type);
// A local signal can have a constant initializer in VHDL
// This may be found in the signal's nexus
// TODO: Make this work for multiple words
vhdl_expr *init = nexus_to_const(ivl_signal_nex(sig, 0));
if (init != NULL)
decl->set_initial(init);
ent->get_arch()->get_scope()->add_decl(decl);
}
break;
case IVL_SIP_INPUT:
ent->get_scope()->add_decl
@ -249,8 +286,10 @@ static void declare_signals(vhdl_entity *ent, ivl_scope_t scope)
static void declare_lpm(vhdl_arch *arch, ivl_scope_t scope)
{
int nlpms = ivl_scope_lpms(scope);
for (int i = 0; i < nlpms; i++)
draw_lpm(arch, ivl_scope_lpm(scope, i));
for (int i = 0; i < nlpms; i++) {
if (draw_lpm(arch, ivl_scope_lpm(scope, i)) != 0)
error("Failed to translate LPM");
}
}
/*