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/*
* nextpnr -- Next Generation Place and Route
*
* Copyright (C) 2020 David Shah <dave@ds0.me>
*
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#include "log.h"
#include "nextpnr.h"
#include "util.h"
#include <queue>
NEXTPNR_NAMESPACE_BEGIN
struct NexusGlobalRouter
{
Context *ctx;
NexusGlobalRouter(Context *ctx) : ctx(ctx){};
// When routing globals; we allow global->local for some tricky cases but never local->local
bool global_pip_filter(PipId pip) const
{
IdString dest_basename(ctx->wire_data(ctx->getPipDstWire(pip)).name);
const std::string &s = dest_basename.str(ctx);
if (s.size() > 2 && (s[0] == 'H' || s[0] == 'V') && s[1] == '0')
return false;
return true;
}
// Dedicated backwards BFS routing for global networks
template <typename Tfilt>
bool backwards_bfs_route(NetInfo *net, size_t user_idx, int iter_limit, bool strict, Tfilt pip_filter)
{
// Queue of wires to visit
std::queue<WireId> visit;
// Wire -> upstream pip
dict<WireId, PipId> backtrace;
// Lookup source and destination wires
WireId src = ctx->getNetinfoSourceWire(net);
WireId dst = ctx->getNetinfoSinkWire(net, net->users.at(user_idx), 0);
if (src == WireId())
log_error("Net '%s' has an invalid source port %s.%s\n", ctx->nameOf(net), ctx->nameOf(net->driver.cell),
ctx->nameOf(net->driver.port));
if (dst == WireId())
log_error("Net '%s' has an invalid sink port %s.%s\n", ctx->nameOf(net),
ctx->nameOf(net->users.at(user_idx).cell), ctx->nameOf(net->users.at(user_idx).port));
if (ctx->getBoundWireNet(src) != net)
ctx->bindWire(src, net, STRENGTH_LOCKED);
if (src == dst) {
// Nothing more to do
return true;
}
visit.push(dst);
backtrace[dst] = PipId();
int iter = 0;
while (!visit.empty() && (iter++ < iter_limit)) {
WireId cursor = visit.front();
visit.pop();
// Search uphill pips
for (PipId pip : ctx->getPipsUphill(cursor)) {
// Skip pip if unavailable, and not because it's already used for this net
if (!ctx->checkPipAvail(pip) && ctx->getBoundPipNet(pip) != net)
continue;
WireId prev = ctx->getPipSrcWire(pip);
// Ditto for the upstream wire
if (!ctx->checkWireAvail(prev) && ctx->getBoundWireNet(prev) != net)
continue;
// Skip already visited wires
if (backtrace.count(prev))
continue;
// Apply our custom pip filter
if (!pip_filter(pip))
continue;
// Add to the queue
visit.push(prev);
backtrace[prev] = pip;
// Check if we are done yet
if (prev == src)
goto done;
}
if (false) {
done:
break;
}
}
if (backtrace.count(src)) {
WireId cursor = src;
std::vector<PipId> pips;
// Create a list of pips on the routed path
while (true) {
PipId pip = backtrace.at(cursor);
if (pip == PipId())
break;
pips.push_back(pip);
cursor = ctx->getPipDstWire(pip);
}
// Reverse that list
std::reverse(pips.begin(), pips.end());
// Bind pips until we hit already-bound routing
for (PipId pip : pips) {
WireId dst = ctx->getPipDstWire(pip);
if (ctx->getBoundWireNet(dst) == net)
break;
ctx->bindPip(pip, net, STRENGTH_LOCKED);
}
return true;
} else {
if (strict)
log_error("Failed to route net '%s' from %s to %s using dedicated routing.\n", ctx->nameOf(net),
ctx->nameOfWire(src), ctx->nameOfWire(dst));
return false;
}
}
bool is_relaxed_sink(const PortRef &sink) const
{
// This DPHY clock port can't be routed without going through some general routing
if (sink.cell->type == id_DPHY_CORE && sink.port == id_URXCKINE)
return true;
return false;
}
void route_clk_net(NetInfo *net)
{
for (size_t i = 0; i < net->users.size(); i++)
backwards_bfs_route(net, i, 1000000, true,
[&](PipId pip) { return is_relaxed_sink(net->users.at(i)) || global_pip_filter(pip); });
log_info(" routed net '%s' using global resources\n", ctx->nameOf(net));
}
void operator()()
{
log_info("Routing globals...\n");
for (auto &net : ctx->nets) {
NetInfo *ni = net.second.get();
CellInfo *drv = ni->driver.cell;
if (drv == nullptr)
continue;
if (drv->type == id_DCC) {
route_clk_net(ni);
continue;
}
}
}
};
void Arch::route_globals()
{
NexusGlobalRouter glb_router(getCtx());
glb_router();
}
NEXTPNR_NAMESPACE_END
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