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/*
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2012 Clifford Wolf <clifford@clifford.at>
*
* 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 "kernel/register.h"
#include "kernel/sigtools.h"
#include "kernel/consteval.h"
#include "kernel/log.h"
#include <sstream>
#include <stdlib.h>
#include <stdio.h>
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
struct proc_dlatch_db_t
{
Module *module;
SigMap sigmap;
dict<Cell*, vector<SigBit>> mux_srcbits;
dict<SigBit, pair<Cell*, int>> mux_drivers;
dict<SigBit, int> sigusers;
proc_dlatch_db_t(Module *module) : module(module), sigmap(module)
{
for (auto cell : module->cells())
{
if (cell->type.in("$mux", "$pmux"))
{
auto sig_y = sigmap(cell->getPort("\\Y"));
for (int i = 0; i < GetSize(sig_y); i++)
mux_drivers[sig_y[i]] = pair<Cell*, int>(cell, i);
pool<SigBit> mux_srcbits_pool;
for (auto bit : sigmap(cell->getPort("\\A")))
mux_srcbits_pool.insert(bit);
for (auto bit : sigmap(cell->getPort("\\B")))
mux_srcbits_pool.insert(bit);
vector<SigBit> mux_srcbits_vec;
for (auto bit : mux_srcbits_pool)
if (bit.wire != nullptr)
mux_srcbits_vec.push_back(bit);
mux_srcbits[cell].swap(mux_srcbits_vec);
}
for (auto &conn : cell->connections())
if (!cell->known() || cell->input(conn.first))
for (auto bit : sigmap(conn.second))
sigusers[bit]++;
}
for (auto wire : module->wires())
if (wire->port_input)
for (auto bit : sigmap(wire))
sigusers[bit]++;
}
bool quickcheck(const SigSpec &haystack, const SigSpec &needle)
{
pool<SigBit> haystack_bits = sigmap(haystack).to_sigbit_pool();
pool<SigBit> needle_bits = sigmap(needle).to_sigbit_pool();
pool<Cell*> cells_queue, cells_visited;
pool<SigBit> bits_queue, bits_visited;
bits_queue = haystack_bits;
while (!bits_queue.empty())
{
for (auto &bit : bits_queue) {
auto it = mux_drivers.find(bit);
if (it != mux_drivers.end())
if (!cells_visited.count(it->second.first))
cells_queue.insert(it->second.first);
bits_visited.insert(bit);
}
bits_queue.clear();
for (auto c : cells_queue) {
for (auto bit : mux_srcbits[c]) {
if (needle_bits.count(bit))
return true;
if (!bits_visited.count(bit))
bits_queue.insert(bit);
}
}
cells_queue.clear();
}
return false;
}
struct rule_node_t
{
// a node is true if "signal" equals "match" and [any
// of the child nodes is true or "children" is empty]
SigBit signal, match;
vector<int> children;
bool operator==(const rule_node_t &other) const {
return signal == other.signal && match == other.match && children == other.children;
}
unsigned int hash() const {
unsigned int h = mkhash_init;
mkhash(h, signal.hash());
mkhash(h, match.hash());
for (auto i : children) mkhash(h, i);
return h;
}
};
enum tf_node_types_t : int {
true_node = 1,
false_node = 2
};
idict<rule_node_t, 3> rules_db;
dict<int, SigBit> rules_sig;
int make_leaf(SigBit signal, SigBit match)
{
rule_node_t node;
node.signal = signal;
node.match = match;
return rules_db(node);
}
int make_inner(SigBit signal, SigBit match, int child)
{
rule_node_t node;
node.signal = signal;
node.match = match;
node.children.push_back(child);
return rules_db(node);
}
int make_inner(const pool<int> &children)
{
rule_node_t node;
node.signal = State::S0;
node.match = State::S0;
node.children = vector<int>(children.begin(), children.end());
std::sort(node.children.begin(), node.children.end());
return rules_db(node);
}
int find_mux_feedback(SigBit haystack, SigBit needle, bool set_undef)
{
if (sigusers[haystack] > 1)
set_undef = false;
if (haystack == needle)
return true_node;
auto it = mux_drivers.find(haystack);
if (it == mux_drivers.end())
return false_node;
Cell *cell = it->second.first;
int index = it->second.second;
SigSpec sig_a = sigmap(cell->getPort("\\A"));
SigSpec sig_b = sigmap(cell->getPort("\\B"));
SigSpec sig_s = sigmap(cell->getPort("\\S"));
int width = GetSize(sig_a);
pool<int> children;
int n = find_mux_feedback(sig_a[index], needle, set_undef);
if (n != false_node) {
if (set_undef && sig_a[index] == needle) {
SigSpec sig = cell->getPort("\\A");
sig[index] = State::Sx;
cell->setPort("\\A", sig);
}
for (int i = 0; i < GetSize(sig_s); i++)
n = make_inner(sig_s[i], State::S0, n);
children.insert(n);
}
for (int i = 0; i < GetSize(sig_s); i++) {
n = find_mux_feedback(sig_b[i*width + index], needle, set_undef);
if (n != false_node) {
if (set_undef && sig_b[i*width + index] == needle) {
SigSpec sig = cell->getPort("\\B");
sig[i*width + index] = State::Sx;
cell->setPort("\\B", sig);
}
children.insert(make_inner(sig_s[i], State::S1, n));
}
}
if (children.empty())
return false_node;
return make_inner(children);
}
SigBit make_hold(int n)
{
if (n == true_node)
return State::S1;
if (n == false_node)
return State::S0;
if (rules_sig.count(n))
return rules_sig.at(n);
const rule_node_t &rule = rules_db[n];
SigSpec and_bits;
if (rule.signal != rule.match) {
if (rule.match == State::S1)
and_bits.append(rule.signal);
else if (rule.match == State::S0)
and_bits.append(module->Not(NEW_ID, rule.signal));
else
and_bits.append(module->Eq(NEW_ID, rule.signal, rule.match));
}
if (!rule.children.empty()) {
SigSpec or_bits;
for (int k : rule.children)
or_bits.append(make_hold(k));
and_bits.append(module->ReduceOr(NEW_ID, or_bits));
}
if (GetSize(and_bits) == 2)
and_bits = module->And(NEW_ID, and_bits[0], and_bits[1]);
log_assert(GetSize(and_bits) == 1);
rules_sig[n] = and_bits[0];
return and_bits[0];
}
};
void proc_dlatch(proc_dlatch_db_t &db, RTLIL::Process *proc)
{
std::vector<RTLIL::SyncRule*> new_syncs;
RTLIL::SigSig latches_bits, nolatches_bits;
dict<SigBit, SigBit> latches_out_in;
dict<SigBit, int> latches_hold;
for (auto sr : proc->syncs)
{
if (sr->type != RTLIL::SyncType::STa) {
new_syncs.push_back(sr);
continue;
}
for (auto ss : sr->actions)
{
db.sigmap.apply(ss.first);
db.sigmap.apply(ss.second);
if (!db.quickcheck(ss.second, ss.first)) {
nolatches_bits.first.append(ss.first);
nolatches_bits.second.append(ss.second);
continue;
}
for (int i = 0; i < GetSize(ss.first); i++)
latches_out_in[ss.first[i]] = ss.second[i];
}
delete sr;
}
latches_out_in.sort();
for (auto &it : latches_out_in) {
int n = db.find_mux_feedback(it.second, it.first, true);
if (n == db.false_node) {
nolatches_bits.first.append(it.first);
nolatches_bits.second.append(it.second);
} else {
latches_bits.first.append(it.first);
latches_bits.second.append(it.second);
latches_hold[it.first] = n;
}
}
int offset = 0;
for (auto chunk : nolatches_bits.first.chunks()) {
SigSpec lhs = chunk, rhs = nolatches_bits.second.extract(offset, chunk.width);
log("No latch inferred for signal `%s.%s' from process `%s.%s'.\n",
db.module->name.c_str(), log_signal(lhs), db.module->name.c_str(), proc->name.c_str());
db.module->connect(lhs, rhs);
offset += chunk.width;
}
offset = 0;
while (offset < GetSize(latches_bits.first))
{
int width = 1;
int n = latches_hold[latches_bits.first[offset]];
Wire *w = latches_bits.first[offset].wire;
if (w != nullptr)
{
while (offset+width < GetSize(latches_bits.first) &&
n == latches_hold[latches_bits.first[offset+width]] &&
w == latches_bits.first[offset+width].wire)
width++;
SigSpec lhs = latches_bits.first.extract(offset, width);
SigSpec rhs = latches_bits.second.extract(offset, width);
Cell *cell = db.module->addDlatch(NEW_ID, db.module->Not(NEW_ID, db.make_hold(n)), rhs, lhs);
log("Latch inferred for signal `%s.%s' from process `%s.%s': %s\n",
db.module->name.c_str(), log_signal(lhs), db.module->name.c_str(), proc->name.c_str(), log_id(cell));
}
offset += width;
}
new_syncs.swap(proc->syncs);
}
struct ProcDlatchPass : public Pass {
ProcDlatchPass() : Pass("proc_dlatch", "extract latches from processes") { }
virtual void help()
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" proc_dlatch [selection]\n");
log("\n");
log("This pass identifies latches in the processes and converts them to\n");
log("d-type latches.\n");
log("\n");
}
virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
{
log_header(design, "Executing PROC_DLATCH pass (convert process syncs to latches).\n");
extra_args(args, 1, design);
for (auto module : design->selected_modules()) {
proc_dlatch_db_t db(module);
for (auto &proc_it : module->processes)
if (design->selected(module, proc_it.second))
proc_dlatch(db, proc_it.second);
}
}
} ProcDlatchPass;
PRIVATE_NAMESPACE_END
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