288 lines
12 KiB
C++
288 lines
12 KiB
C++
/*
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* nextpnr -- Next Generation Place and Route
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*
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* Copyright (C) 2018 David Shah <david@symbioticeda.com>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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*/
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#include "chains.h"
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#include <algorithm>
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#include <vector>
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#include "cells.h"
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#include "design_utils.h"
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#include "log.h"
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#include "place_common.h"
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#include "util.h"
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NEXTPNR_NAMESPACE_BEGIN
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struct CellChain
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{
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std::vector<CellInfo *> cells;
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};
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// Generic chain finder
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template <typename F1, typename F2, typename F3>
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std::vector<CellChain> find_chains(const Context *ctx, F1 cell_type_predicate, F2 get_previous, F3 get_next,
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size_t min_length = 2)
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{
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std::set<IdString> chained;
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std::vector<CellChain> chains;
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for (auto cell : sorted(ctx->cells)) {
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if (chained.find(cell.first) != chained.end())
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continue;
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CellInfo *ci = cell.second;
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if (cell_type_predicate(ctx, ci)) {
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CellInfo *start = ci;
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CellInfo *prev_start = ci;
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while (prev_start != nullptr) {
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start = prev_start;
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prev_start = get_previous(ctx, start);
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}
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CellChain chain;
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CellInfo *end = start;
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while (end != nullptr) {
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chain.cells.push_back(end);
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end = get_next(ctx, end);
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}
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if (chain.cells.size() >= min_length) {
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chains.push_back(chain);
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for (auto c : chain.cells)
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chained.insert(c->name);
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}
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}
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}
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return chains;
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}
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class ChainConstrainer
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{
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private:
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Context *ctx;
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// Split a carry chain into multiple legal chains
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std::vector<CellChain> split_carry_chain(CellChain &carryc)
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{
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bool start_of_chain = true;
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std::vector<CellChain> chains;
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std::vector<const CellInfo *> tile;
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const int max_length = (ctx->chip_info->height - 2) * 8 - 2;
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auto curr_cell = carryc.cells.begin();
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while (curr_cell != carryc.cells.end()) {
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CellInfo *cell = *curr_cell;
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if (tile.size() >= 8) {
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tile.clear();
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}
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if (start_of_chain) {
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tile.clear();
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chains.emplace_back();
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start_of_chain = false;
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if (cell->ports.at(ctx->id("CIN")).net) {
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// CIN is not constant and not part of a chain. Must feed in from fabric
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CellInfo *feedin = make_carry_feed_in(cell, cell->ports.at(ctx->id("CIN")));
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chains.back().cells.push_back(feedin);
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tile.push_back(feedin);
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}
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}
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tile.push_back(cell);
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chains.back().cells.push_back(cell);
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bool split_chain = (!ctx->logicCellsCompatible(tile)) || (int(chains.back().cells.size()) > max_length);
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if (split_chain) {
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CellInfo *passout = make_carry_pass_out(cell->ports.at(ctx->id("COUT")));
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tile.pop_back();
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chains.back().cells.back() = passout;
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start_of_chain = true;
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} else {
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NetInfo *carry_net = cell->ports.at(ctx->id("COUT")).net;
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bool at_end = (curr_cell == carryc.cells.end() - 1);
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if (carry_net != nullptr && (carry_net->users.size() > 1 || at_end)) {
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if (carry_net->users.size() > 2 ||
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(net_only_drives(ctx, carry_net, is_lc, ctx->id("I3"), false) !=
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net_only_drives(ctx, carry_net, is_lc, ctx->id("CIN"), false)) ||
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(at_end && !net_only_drives(ctx, carry_net, is_lc, ctx->id("I3"), true))) {
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CellInfo *passout = make_carry_pass_out(cell->ports.at(ctx->id("COUT")));
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chains.back().cells.push_back(passout);
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tile.push_back(passout);
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start_of_chain = true;
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}
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}
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++curr_cell;
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}
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}
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return chains;
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}
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// Insert a logic cell to legalise a COUT->fabric connection
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CellInfo *make_carry_pass_out(PortInfo &cout_port)
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{
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NPNR_ASSERT(cout_port.net != nullptr);
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std::unique_ptr<CellInfo> lc = create_ice_cell(ctx, ctx->id("ICESTORM_LC"));
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lc->params[ctx->id("LUT_INIT")] = "65280"; // 0xff00: O = I3
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lc->params[ctx->id("CARRY_ENABLE")] = "1";
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lc->ports.at(ctx->id("O")).net = cout_port.net;
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std::unique_ptr<NetInfo> co_i3_net(new NetInfo());
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co_i3_net->name = ctx->id(lc->name.str(ctx) + "$I3");
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co_i3_net->driver = cout_port.net->driver;
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PortRef i3_r;
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i3_r.port = ctx->id("I3");
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i3_r.cell = lc.get();
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co_i3_net->users.push_back(i3_r);
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PortRef o_r;
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o_r.port = ctx->id("O");
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o_r.cell = lc.get();
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cout_port.net->driver = o_r;
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lc->ports.at(ctx->id("I3")).net = co_i3_net.get();
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cout_port.net = co_i3_net.get();
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IdString co_i3_name = co_i3_net->name;
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NPNR_ASSERT(ctx->nets.find(co_i3_name) == ctx->nets.end());
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ctx->nets[co_i3_name] = std::move(co_i3_net);
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IdString name = lc->name;
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ctx->assignCellInfo(lc.get());
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ctx->cells[lc->name] = std::move(lc);
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return ctx->cells[name].get();
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}
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// Insert a logic cell to legalise a CIN->fabric connection
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CellInfo *make_carry_feed_in(CellInfo *cin_cell, PortInfo &cin_port)
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{
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NPNR_ASSERT(cin_port.net != nullptr);
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std::unique_ptr<CellInfo> lc = create_ice_cell(ctx, ctx->id("ICESTORM_LC"));
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lc->params[ctx->id("CARRY_ENABLE")] = "1";
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lc->params[ctx->id("CIN_CONST")] = "1";
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lc->params[ctx->id("CIN_SET")] = "1";
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lc->ports.at(ctx->id("I1")).net = cin_port.net;
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cin_port.net->users.erase(std::remove_if(cin_port.net->users.begin(), cin_port.net->users.end(),
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[cin_cell, cin_port](const PortRef &usr) {
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return usr.cell == cin_cell && usr.port == cin_port.name;
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}));
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PortRef i1_ref;
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i1_ref.cell = lc.get();
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i1_ref.port = ctx->id("I1");
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lc->ports.at(ctx->id("I1")).net->users.push_back(i1_ref);
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std::unique_ptr<NetInfo> out_net(new NetInfo());
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out_net->name = ctx->id(lc->name.str(ctx) + "$O");
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PortRef drv_ref;
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drv_ref.port = ctx->id("COUT");
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drv_ref.cell = lc.get();
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out_net->driver = drv_ref;
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lc->ports.at(ctx->id("COUT")).net = out_net.get();
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PortRef usr_ref;
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usr_ref.port = cin_port.name;
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usr_ref.cell = cin_cell;
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out_net->users.push_back(usr_ref);
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cin_cell->ports.at(cin_port.name).net = out_net.get();
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IdString out_net_name = out_net->name;
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NPNR_ASSERT(ctx->nets.find(out_net_name) == ctx->nets.end());
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ctx->nets[out_net_name] = std::move(out_net);
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IdString name = lc->name;
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ctx->assignCellInfo(lc.get());
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ctx->cells[lc->name] = std::move(lc);
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return ctx->cells[name].get();
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}
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void process_carries()
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{
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std::vector<CellChain> carry_chains =
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find_chains(ctx, [](const Context *ctx, const CellInfo *cell) { return is_lc(ctx, cell); },
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[](const Context *ctx, const
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CellInfo *cell) {
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CellInfo *carry_prev =
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net_driven_by(ctx, cell->ports.at(ctx->id("CIN")).net, is_lc, ctx->id("COUT"));
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if (carry_prev != nullptr)
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return carry_prev;
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/*CellInfo *i3_prev = net_driven_by(ctx, cell->ports.at(ctx->id("I3")).net, is_lc,
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ctx->id("COUT")); if (i3_prev != nullptr) return i3_prev;*/
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return (CellInfo *)nullptr;
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},
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[](const Context *ctx, const CellInfo *cell) {
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CellInfo *carry_next = net_only_drives(ctx, cell->ports.at(ctx->id("COUT")).net, is_lc,
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ctx->id("CIN"), false);
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if (carry_next != nullptr)
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return carry_next;
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/*CellInfo *i3_next =
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net_only_drives(ctx, cell->ports.at(ctx->id("COUT")).net, is_lc, ctx->id("I3"),
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false); if (i3_next != nullptr) return i3_next;*/
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return (CellInfo *)nullptr;
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});
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std::unordered_set<IdString> chained;
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for (auto &base_chain : carry_chains) {
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for (auto c : base_chain.cells)
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chained.insert(c->name);
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}
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// Any cells not in chains, but with carry enabled, must also be put in a single-carry chain
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// for correct processing
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for (auto cell : sorted(ctx->cells)) {
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CellInfo *ci = cell.second;
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if (chained.find(cell.first) == chained.end() && is_lc(ctx, ci) &&
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bool_or_default(ci->params, ctx->id("CARRY_ENABLE"))) {
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CellChain sChain;
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sChain.cells.push_back(ci);
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chained.insert(cell.first);
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carry_chains.push_back(sChain);
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}
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}
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std::vector<CellChain> all_chains;
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// Chain splitting
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for (auto &base_chain : carry_chains) {
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if (ctx->verbose) {
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log_info("Found carry chain: \n");
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for (auto entry : base_chain.cells)
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log_info(" %s\n", entry->name.c_str(ctx));
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log_info("\n");
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}
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std::vector<CellChain> split_chains = split_carry_chain(base_chain);
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for (auto &chain : split_chains) {
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all_chains.push_back(chain);
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}
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}
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// Actual chain placement
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for (auto &chain : all_chains) {
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if (ctx->verbose)
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log_info("Placing carry chain starting at '%s'\n", chain.cells.front()->name.c_str(ctx));
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// Place carry chain
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chain.cells.at(0)->constr_abs_z = true;
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chain.cells.at(0)->constr_z = 0;
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for (int i = 1; i < int(chain.cells.size()); i++) {
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chain.cells.at(i)->constr_x = 0;
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chain.cells.at(i)->constr_y = (i / 8);
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chain.cells.at(i)->constr_z = i % 8;
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chain.cells.at(i)->constr_abs_z = true;
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chain.cells.at(i)->constr_parent = chain.cells.at(0);
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chain.cells.at(0)->constr_children.push_back(chain.cells.at(i));
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}
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}
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}
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public:
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ChainConstrainer(Context *ctx) : ctx(ctx){};
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void constrain_chains() { process_carries(); }
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};
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void constrain_chains(Context *ctx)
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{
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log_info("Constraining chains...\n");
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ChainConstrainer(ctx).constrain_chains();
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}
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NEXTPNR_NAMESPACE_END
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