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/*
* nextpnr -- Next Generation Place and Route
*
* Copyright (C) 2018 David Shah <david@symbioticeda.com>
*
* 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 "timing.h"
#include <algorithm>
#include <unordered_map>
#include <utility>
#include "log.h"
#include "util.h"
NEXTPNR_NAMESPACE_BEGIN
static delay_t follow_net(Context *ctx, NetInfo *net, int path_length, delay_t slack);
// Follow a path, returning budget to annotate
static delay_t follow_user_port(Context *ctx, PortRef &user, int path_length, delay_t slack)
{
delay_t value;
if (ctx->getPortClock(user.cell, user.port) != IdString()) {
// At the end of a timing path (arguably, should check setup time
// here too)
value = slack / path_length;
} else {
// Default to the path ending here, if no further paths found
value = slack / path_length;
// Follow outputs of the user
for (auto port : user.cell->ports) {
if (port.second.type == PORT_OUT) {
delay_t comb_delay;
// Look up delay through this path
bool is_path = ctx->getCellDelay(user.cell, user.port, port.first, comb_delay);
if (is_path) {
NetInfo *net = port.second.net;
if (net) {
delay_t path_budget = follow_net(ctx, net, path_length, slack - comb_delay);
value = std::min(value, path_budget);
}
}
}
}
}
if (value < user.budget) {
user.budget = value;
}
return value;
}
static delay_t follow_net(Context *ctx, NetInfo *net, int path_length, delay_t slack)
{
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));
}
return net_budget;
}
void assign_budget(Context *ctx)
{
log_break();
log_info("Annotating ports with timing budgets\n");
// Clear delays to a very high value first
delay_t default_slack = delay_t(1.0e12 / ctx->target_freq);
for (auto &net : ctx->nets) {
for (auto &usr : net.second->users) {
usr.budget = default_slack;
}
}
// Go through all clocked drivers and set up paths
for (auto &cell : ctx->cells) {
for (auto port : cell.second->ports) {
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
if (port.second.net)
follow_net(ctx, port.second.net, 0, slack);
}
}
}
}
// Post-allocation check
for (auto &net : ctx->nets) {
for (auto user : net.second->users) {
if (user.budget < 0)
log_warning("port %s.%s, connected to net '%s', has negative "
"timing budget of %fns\n",
user.cell->name.c_str(ctx), user.port.c_str(ctx), net.first.c_str(ctx),
ctx->getDelayNS(user.budget));
if (ctx->verbose)
log_info("port %s.%s, connected to net '%s', has "
"timing budget of %fns\n",
user.cell->name.c_str(ctx), user.port.c_str(ctx), net.first.c_str(ctx),
ctx->getDelayNS(user.budget));
}
}
log_info("Checksum: 0x%08x\n", ctx->checksum());
}
typedef std::unordered_map<const PortInfo*, delay_t> updates_t;
typedef std::unordered_map<const PortInfo*, delay_t> delays_t;
static delay_t follow_net_update(Context *ctx, NetInfo *net, int path_length, delay_t slack, const delays_t& delays, updates_t& updates);
// Follow a path, returning budget to annotate
static delay_t follow_user_port_update(Context *ctx, PortRef &user, int path_length, delay_t slack, const delays_t& delays, updates_t& updates)
{
delay_t value;
if (ctx->getPortClock(user.cell, user.port) != IdString()) {
// At the end of a timing path (arguably, should check setup time
// here too)
value = slack / path_length;
} else {
// Default to the path ending here, if no further paths found
value = slack / path_length;
// Follow outputs of the user
for (auto& port : user.cell->ports) {
if (port.second.type == PORT_OUT) {
delay_t comb_delay;
// Look up delay through this path
bool is_path = ctx->getCellDelay(user.cell, user.port, port.first, comb_delay);
if (is_path) {
NetInfo *net = port.second.net;
if (net) {
delay_t path_budget = follow_net_update(ctx, net, path_length, slack - comb_delay, delays, updates);
value = std::min(value, path_budget);
}
}
}
}
}
auto ret = updates.emplace(&user.cell->ports.at(user.port), value);
if (!ret.second && value < ret.first->second) {
ret.first->second = value;
}
return value;
}
static delay_t follow_net_update(Context *ctx, NetInfo *net, int path_length, delay_t slack, const delays_t& delays,updates_t& updates)
{
delay_t net_budget = slack / (path_length + 1);
for (auto& usr : net->users) {
net_budget = std::min(net_budget, follow_user_port_update(ctx, usr, path_length + 1, slack - get_or_default(delays, &usr.cell->ports.at(usr.port), 0.), delays, updates));
}
return net_budget;
}
void update_budget(Context *ctx)
{
delays_t delays;
updates_t updates;
// Compute the delay for every pin on every net
for (auto &n : ctx->nets) {
auto net = n.second.get();
int driver_x, driver_y;
bool driver_gb;
CellInfo *driver_cell = net->driver.cell;
if (!driver_cell)
continue;
if (driver_cell->bel == BelId())
continue;
ctx->estimatePosition(driver_cell->bel, driver_x, driver_y, driver_gb);
WireId drv_wire = ctx->getWireBelPin(driver_cell->bel, ctx->portPinFromId(net->driver.port));
if (driver_gb)
continue;
for (auto& load : net->users) {
if (load.cell == nullptr)
continue;
CellInfo *load_cell = load.cell;
if (load_cell->bel == BelId())
continue;
WireId user_wire = ctx->getWireBelPin(load_cell->bel, ctx->portPinFromId(load.port));
delay_t raw_wl = ctx->estimateDelay(drv_wire, user_wire);
delays.emplace(&load_cell->ports.at(load.port), raw_wl);
}
}
// Go through all clocked drivers and distribute the available path slack evenly into every budget
for (auto &cell : ctx->cells) {
for (auto& port : cell.second->ports) {
if (port.second.type == PORT_OUT) {
IdString clock_domain = ctx->getPortClock(cell.second.get(), port.first);
if (clock_domain != IdString()) {
if (port.second.net)
follow_net_update(ctx, port.second.net, 0, delay_t(1.0e12 / ctx->target_freq) - get_or_default(delays, &port.second, 0.), delays, updates);
}
}
}
}
// Update the budgets
for (auto &net : ctx->nets) {
for (auto& user : net.second->users) {
auto pi = &user.cell->ports.at(user.port);
auto it = updates.find(pi);
if (it == updates.end()) continue;
user.budget = delays.at(pi) + it->second;
// Post-update check
// if (user.budget < 0)
// log_warning("port %s.%s, connected to net '%s', has negative "
// "timing budget of %fns\n",
// user.cell->name.c_str(ctx), user.port.c_str(ctx), net.first.c_str(ctx),
// ctx->getDelayNS(user.budget));
// if (ctx->verbose)
// log_info("port %s.%s, connected to net '%s', has "
// "timing budget of %fns\n",
// user.cell->name.c_str(ctx), user.port.c_str(ctx), net.first.c_str(ctx),
// ctx->getDelayNS(user.budget));
}
}
}
NEXTPNR_NAMESPACE_END
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