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Fix for br947. 

When performing the initial assignment for a procedural continuous
assignment, any previous continuous assignment to the destination
signal must be unlinked first, otherwise the initial value for the
assignment will propagate to any other nets that are driven by the
original source signal.
This commit is contained in:
Martin Whitaker 2014-02-26 08:39:33 +00:00
parent a3450bf856
commit 1f81d4c081
1 changed files with 35 additions and 15 deletions
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50
vvp/vthread.cc
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2001-2013 Stephen Williams (steve@icarus.com)
* Copyright (c) 2001-2014 Stephen Williams (steve@icarus.com)
*
* This source code is free software; you can redistribute it
* and/or modify it in source code form under the terms of the GNU
@ -1431,7 +1431,7 @@ bool of_BREAKPOINT(vthread_t, vvp_code_t)
}
/*
* the %cassign/link instruction connects a source node to a
* The %cassign/link instruction connects a source node to a
* destination node. The destination node must be a signal, as it is
* marked with the source of the cassign so that it may later be
* unlinked without specifically knowing the source that this
@ -1446,17 +1446,8 @@ bool of_CASSIGN_LINK(vthread_t, vvp_code_t cp)
= dynamic_cast<vvp_fun_signal_base*>(dst->fun);
assert(sig);
/* Detect the special case that we are already continuous
assigning the source onto the destination. */
if (sig->cassign_link == src)
return true;
/* If there is an existing cassign driving this node, then
unlink it. We can have only 1 cassign at a time. */
if (sig->cassign_link != 0) {
vvp_net_ptr_t tmp (dst, 1);
sig->cassign_link->unlink(tmp);
}
/* Any previous continuous assign should have been removed already. */
assert(sig->cassign_link == 0);
sig->cassign_link = src;
@ -1469,7 +1460,27 @@ bool of_CASSIGN_LINK(vthread_t, vvp_code_t cp)
}
/*
* the %cassign/v instruction invokes a continuous assign of a
* If there is an existing continuous assign linked to the destination
* node, unlink it. This must be done before applying a new continuous
* assign, otherwise the initial assigned value will be propagated to
* any other nodes driven by the old continuous assign source.
*/
static void cassign_unlink(vvp_net_t*dst)
{
vvp_fun_signal_base*sig
= dynamic_cast<vvp_fun_signal_base*>(dst->fun);
assert(sig);
if (sig->cassign_link == 0)
return;
vvp_net_ptr_t tmp (dst, 1);
sig->cassign_link->unlink(tmp);
sig->cassign_link = 0;
}
/*
* The %cassign/v instruction invokes a continuous assign of a
* constant value to a signal. The instruction arguments are:
*
* %cassign/v <net>, <base>, <wid> ;
@ -1486,10 +1497,13 @@ bool of_CASSIGN_V(vthread_t thr, vvp_code_t cp)
unsigned base = cp->bit_idx[0];
unsigned wid = cp->bit_idx[1];
/* Remove any previous continuous assign to this net. */
cassign_unlink(net);
/* Collect the thread bits into a vector4 item. */
vvp_vector4_t value = vthread_bits_to_vector(thr, base, wid);
/* set the value into port 1 of the destination. */
/* Set the value into port 1 of the destination. */
vvp_net_ptr_t ptr (net, 1);
vvp_send_vec4(ptr, value, 0);
@ -1501,6 +1515,9 @@ bool of_CASSIGN_WR(vthread_t thr, vvp_code_t cp)
vvp_net_t*net = cp->net;
double value = thr->pop_real();
/* Remove any previous continuous assign to this net. */
cassign_unlink(net);
/* Set the value into port 1 of the destination. */
vvp_net_ptr_t ptr (net, 1);
vvp_send_real(ptr, value, 0);
@ -1514,6 +1531,9 @@ bool of_CASSIGN_X0(vthread_t thr, vvp_code_t cp)
unsigned base = cp->bit_idx[0];
unsigned wid = cp->bit_idx[1];
/* Remove any previous continuous assign to this net. */
cassign_unlink(net);
// Implicitly, we get the base into the target vector from the
// X0 register.
long index = thr->words[0].w_int;