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Also subtract net delay from slack

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This commit is contained in:
Eddie Hung 2018-07-24 22:39:51 -07:00
parent 9382938661
commit a69745060e
1 changed files with 8 additions and 3 deletions
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11
common/timing.cc
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@ -68,8 +68,9 @@ static delay_t follow_user_port(Context *ctx, PortRef &user, int path_length, de
static delay_t follow_net(Context *ctx, NetInfo *net, int path_length, delay_t slack, UpdateMap &updates)
{
delay_t net_budget = slack / (path_length + 1);
for (auto &usr : net->users) {
net_budget = std::min(net_budget, follow_user_port(ctx, usr, path_length + 1, slack, updates));
for (unsigned i = 0; i < net->users.size(); ++i) {
auto &usr = net->users[i];
net_budget = std::min(net_budget, follow_user_port(ctx, usr, path_length + 1, slack - ctx->getNetinfoRouteDelay(net, i), updates));
}
return net_budget;
}
@ -141,8 +142,12 @@ void update_budget(Context *ctx)
if (port.second.type == PORT_OUT) {
IdString clock_domain = ctx->getPortClock(cell.second.get(), port.first);
if (clock_domain != IdString()) {
delay_t slack = delay_t(1.0e12 / ctx->target_freq); // TODO: clock constraints
delay_t clkToQ;
if (ctx->getCellDelay(cell.second.get(), clock_domain, port.first, clkToQ))
slack -= clkToQ;
if (port.second.net)
follow_net(ctx, port.second.net, 0, delay_t(1.0e12 / ctx->target_freq), updates);
follow_net(ctx, port.second.net, 0, slack, updates);
}
}
}