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Handle case that delay output is pending when new event arrives 

If the delay has an event pending for the current time, then use
that as a reference for calculating the next delay. If that is not
done, then the delay calculated against the wrong reference might
result in zero, and bad results.
(cherry picked from commit f07577db11)
This commit is contained in:
Stephen Williams 2009-11-23 18:27:14 -08:00
parent d090fd7a17
commit 0cc8285a01
1 changed files with 21 additions and 9 deletions
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30
vvp/delay.cc
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@ -269,17 +269,23 @@ void vvp_fun_delay::recv_vec4(vvp_net_ptr_t port, const vvp_vector4_t&bit,
} else {
assert(type_ == VEC4_DELAY);
// Use as a reference for calculating the delay the
// current value of the output. Detect and handle the
// special case that the event list contains the current
// value as a zero-delay-remaining event.
const vvp_vector4_t&use_vec4 = (list_ && list_->next->sim_time == schedule_simtime())? list_->next->ptr_vec4 : cur_vec4_;
/* How many bits to compare? */
unsigned use_wid = cur_vec4_.size();
unsigned use_wid = use_vec4.size();
if (bit.size() < use_wid) use_wid = bit.size();
/* Scan the vectors looking for delays. Select the maximum
delay encountered. */
use_delay = delay_.get_delay(cur_vec4_.value(0), bit.value(0));
use_delay = delay_.get_delay(use_vec4.value(0), bit.value(0));
for (unsigned idx = 1 ; idx < use_wid ; idx += 1) {
vvp_time64_t tmp;
tmp = delay_.get_delay(cur_vec4_.value(idx), bit.value(idx));
tmp = delay_.get_delay(use_vec4.value(idx), bit.value(idx));
if (tmp > use_delay) use_delay = tmp;
}
}
@ -292,7 +298,7 @@ void vvp_fun_delay::recv_vec4(vvp_net_ptr_t port, const vvp_vector4_t&bit,
vvp_time64_t use_simtime = schedule_simtime() + use_delay;
/* And propagate it. */
if (use_delay == 0) {
if (use_delay == 0 && list_ == 0) {
cur_vec4_ = bit;
initial_ = false;
vvp_send_vec4(net_->out, cur_vec4_, 0);
@ -325,18 +331,24 @@ void vvp_fun_delay::recv_vec8(vvp_net_ptr_t port, const vvp_vector8_t&bit)
} else {
assert(type_ == VEC8_DELAY);
// Use as a reference for calculating the delay the
// current value of the output. Detect and handle the
// special case that the event list contains the current
// value as a zero-delay-remaining event.
const vvp_vector8_t&use_vec8 = (list_ && list_->next->sim_time == schedule_simtime())? list_->next->ptr_vec8 : cur_vec8_;
/* How many bits to compare? */
unsigned use_wid = cur_vec8_.size();
unsigned use_wid = use_vec8.size();
if (bit.size() < use_wid) use_wid = bit.size();
/* Scan the vectors looking for delays. Select the maximum
delay encountered. */
use_delay = delay_.get_delay(cur_vec8_.value(0).value(),
use_delay = delay_.get_delay(use_vec8.value(0).value(),
bit.value(0).value());
for (unsigned idx = 1 ; idx < use_wid ; idx += 1) {
vvp_time64_t tmp;
tmp = delay_.get_delay(cur_vec8_.value(idx).value(),
tmp = delay_.get_delay(use_vec8.value(idx).value(),
bit.value(idx).value());
if (tmp > use_delay) use_delay = tmp;
}
@ -350,7 +362,7 @@ void vvp_fun_delay::recv_vec8(vvp_net_ptr_t port, const vvp_vector8_t&bit)
vvp_time64_t use_simtime = schedule_simtime() + use_delay;
/* And propagate it. */
if (use_delay == 0) {
if (use_delay == 0 && list_ == 0) {
cur_vec8_ = bit;
initial_ = false;
vvp_send_vec8(net_->out, cur_vec8_);
@ -409,7 +421,7 @@ void vvp_fun_delay::recv_real(vvp_net_ptr_t port, double bit,
vvp_time64_t use_simtime = schedule_simtime() + use_delay;
if (use_delay == 0) {
if (use_delay == 0 && list_ == 0) {
cur_real_ = bit;
initial_ = false;
vvp_send_real(net_->out, cur_real_, 0);