verilog_backend.cc

Go to the documentation of this file.

/*
 *  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.
 *
 *  ---
 *
 *  A simple and straightforward verilog backend.
 *
 *  Note that RTLIL processes can't always be mapped easily to a Verilog
 *  process. Therefore this frontend should only be used to export a
 *  Verilog netlist (i.e. after the "proc" pass has converted all processes
 *  to logic networks and registers).
 *
 */

#include "kernel/register.h"
#include "kernel/celltypes.h"
#include "kernel/log.h"
#include <string>
#include <sstream>
#include <set>
#include <map>

USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN

bool norename, noattr, attr2comment, noexpr;
int auto_name_counter, auto_name_offset, auto_name_digits;
std::map<RTLIL::IdString, int> auto_name_map;
std::set<RTLIL::IdString> reg_wires, reg_ct;

RTLIL::Module *active_module;

void reset_auto_counter_id(RTLIL::IdString id, bool may_rename)
{
    const char *str = id.c_str();

    if (*str == '$' && may_rename && !norename)
        auto_name_map[id] = auto_name_counter++;

    if (str[0] != '\\' || str[1] != '_' || str[2] == 0)
        return;

    for (int i = 2; str[i] != 0; i++) {
        if (str[i] == '_' && str[i+1] == 0)
            continue;
        if (str[i] < '0' || str[i] > '9')
            return;
    }

    int num = atoi(str+2);
    if (num >= auto_name_offset)
        auto_name_offset = num + 1;
}

void reset_auto_counter(RTLIL::Module *module)
{
    auto_name_map.clear();
    auto_name_counter = 0;
    auto_name_offset = 0;

    reset_auto_counter_id(module->name, false);

    for (auto it = module->wires_.begin(); it != module->wires_.end(); it++)
        reset_auto_counter_id(it->second->name, true);

    for (auto it = module->cells_.begin(); it != module->cells_.end(); it++) {
        reset_auto_counter_id(it->second->name, true);
        reset_auto_counter_id(it->second->type, false);
    }

    for (auto it = module->processes.begin(); it != module->processes.end(); it++)
        reset_auto_counter_id(it->second->name, false);

    auto_name_digits = 1;
    for (size_t i = 10; i < auto_name_offset + auto_name_map.size(); i = i*10)
        auto_name_digits++;

    for (auto it = auto_name_map.begin(); it != auto_name_map.end(); it++)
        log("  renaming `%s' to `_%0*d_'.\n", it->first.c_str(), auto_name_digits, auto_name_offset + it->second);
}

std::string id(RTLIL::IdString internal_id, bool may_rename = true)
{
    const char *str = internal_id.c_str();
    bool do_escape = false;

    if (may_rename && auto_name_map.count(internal_id) != 0) {
        char buffer[100];
        snprintf(buffer, 100, "_%0*d_", auto_name_digits, auto_name_offset + auto_name_map[internal_id]);
        return std::string(buffer);
    }

    if (*str == '\\')
        str++;

    if ('0' <= *str && *str <= '9')
        do_escape = true;

    for (int i = 0; str[i]; i++)
    {
        if ('0' <= str[i] && str[i] <= '9')
            continue;
        if ('a' <= str[i] && str[i] <= 'z')
            continue;
        if ('A' <= str[i] && str[i] <= 'Z')
            continue;
        if (str[i] == '_')
            continue;
        do_escape = true;
        break;
    }

    if (do_escape)
        return "\\" + std::string(str) + " ";
    return std::string(str);
}

bool is_reg_wire(RTLIL::SigSpec sig, std::string &reg_name)
{
    if (!sig.is_chunk() || sig.as_chunk().wire == NULL)
        return false;

    RTLIL::SigChunk chunk = sig.as_chunk();

    if (reg_wires.count(chunk.wire->name) == 0)
        return false;

    reg_name = id(chunk.wire->name);
    if (sig.size() != chunk.wire->width) {
        if (sig.size() == 1)
            reg_name += stringf("[%d]", chunk.wire->start_offset +  chunk.offset);
        else
            reg_name += stringf("[%d:%d]", chunk.wire->start_offset +  chunk.offset + chunk.width - 1,
                    chunk.wire->start_offset +  chunk.offset);
    }

    return true;
}

void dump_const(std::ostream &f, const RTLIL::Const &data, int width = -1, int offset = 0, bool no_decimal = false, bool set_signed = false)
{
    if (width < 0)
        width = data.bits.size() - offset;
    if ((data.flags & RTLIL::CONST_FLAG_STRING) == 0 || width != (int)data.bits.size()) {
        if (width == 32 && !no_decimal) {
            int32_t val = 0;
            for (int i = offset+width-1; i >= offset; i--) {
                log_assert(i < (int)data.bits.size());
                if (data.bits[i] != RTLIL::S0 && data.bits[i] != RTLIL::S1)
                    goto dump_bits;
                if (data.bits[i] == RTLIL::S1 && (i - offset) == 31)
                    goto dump_bits;
                if (data.bits[i] == RTLIL::S1)
                    val |= 1 << (i - offset);
            }
            f << stringf("32'%sd%d", set_signed ? "s" : "", val);
        } else {
    dump_bits:
            f << stringf("%d'%sb", width, set_signed ? "s" : "");
            if (width == 0)
                f << stringf("0");
            for (int i = offset+width-1; i >= offset; i--) {
                log_assert(i < (int)data.bits.size());
                switch (data.bits[i]) {
                case RTLIL::S0: f << stringf("0"); break;
                case RTLIL::S1: f << stringf("1"); break;
                case RTLIL::Sx: f << stringf("x"); break;
                case RTLIL::Sz: f << stringf("z"); break;
                case RTLIL::Sa: f << stringf("z"); break;
                case RTLIL::Sm: log_error("Found marker state in final netlist.");
                }
            }
        }
    } else {
        f << stringf("\"");
        std::string str = data.decode_string();
        for (size_t i = 0; i < str.size(); i++) {
            if (str[i] == '\n')
                f << stringf("\\n");
            else if (str[i] == '\t')
                f << stringf("\\t");
            else if (str[i] < 32)
                f << stringf("\\%03o", str[i]);
            else if (str[i] == '"')
                f << stringf("\\\"");
            else if (str[i] == '\\')
                f << stringf("\\\\");
            else
                f << str[i];
        }
        f << stringf("\"");
    }
}

void dump_sigchunk(std::ostream &f, const RTLIL::SigChunk &chunk, bool no_decimal = false)
{
    if (chunk.wire == NULL) {
        dump_const(f, chunk.data, chunk.width, chunk.offset, no_decimal);
    } else {
        if (chunk.width == chunk.wire->width && chunk.offset == 0) {
            f << stringf("%s", id(chunk.wire->name).c_str());
        } else if (chunk.width == 1) {
            if (chunk.wire->upto)
                f << stringf("%s[%d]", id(chunk.wire->name).c_str(), (chunk.wire->width - chunk.offset - 1) + chunk.wire->start_offset);
            else
                f << stringf("%s[%d]", id(chunk.wire->name).c_str(), chunk.offset + chunk.wire->start_offset);
        } else {
            if (chunk.wire->upto)
                f << stringf("%s[%d:%d]", id(chunk.wire->name).c_str(),
                        (chunk.wire->width - (chunk.offset + chunk.width - 1) - 1) + chunk.wire->start_offset,
                        (chunk.wire->width - chunk.offset - 1) + chunk.wire->start_offset);
            else
                f << stringf("%s[%d:%d]", id(chunk.wire->name).c_str(),
                        (chunk.offset + chunk.width - 1) + chunk.wire->start_offset,
                        chunk.offset + chunk.wire->start_offset);
        }
    }
}

void dump_sigspec(std::ostream &f, const RTLIL::SigSpec &sig)
{
    if (sig.is_chunk()) {
        dump_sigchunk(f, sig.as_chunk());
    } else {
        f << stringf("{ ");
        for (auto it = sig.chunks().rbegin(); it != sig.chunks().rend(); it++) {
            if (it != sig.chunks().rbegin())
                f << stringf(", ");
            dump_sigchunk(f, *it, true);
        }
        f << stringf(" }");
    }
}

void dump_attributes(std::ostream &f, std::string indent, std::map<RTLIL::IdString, RTLIL::Const> &attributes, char term = '\n')
{
    if (noattr)
        return;
    for (auto it = attributes.begin(); it != attributes.end(); it++) {
        f << stringf("%s" "%s %s", indent.c_str(), attr2comment ? "/*" : "(*", id(it->first).c_str());
        f << stringf(" = ");
        dump_const(f, it->second);
        f << stringf(" %s%c", attr2comment ? "*/" : "*)", term);
    }
}

void dump_wire(std::ostream &f, std::string indent, RTLIL::Wire *wire)
{
    dump_attributes(f, indent, wire->attributes);
#if 0
    if (wire->port_input && !wire->port_output)
        f << stringf("%s" "input %s", indent.c_str(), reg_wires.count(wire->name) ? "reg " : "");
    else if (!wire->port_input && wire->port_output)
        f << stringf("%s" "output %s", indent.c_str(), reg_wires.count(wire->name) ? "reg " : "");
    else if (wire->port_input && wire->port_output)
        f << stringf("%s" "inout %s", indent.c_str(), reg_wires.count(wire->name) ? "reg " : "");
    else
        f << stringf("%s" "%s ", indent.c_str(), reg_wires.count(wire->name) ? "reg" : "wire");
    if (wire->width != 1)
        f << stringf("[%d:%d] ", wire->width - 1 + wire->start_offset, wire->start_offset);
    f << stringf("%s;\n", id(wire->name).c_str());
#else
    // do not use Verilog-2k "outut reg" syntax in verilog export
    std::string range = "";
    if (wire->width != 1) {
        if (wire->upto)
            range = stringf(" [%d:%d]", wire->start_offset, wire->width - 1 + wire->start_offset);
        else
            range = stringf(" [%d:%d]", wire->width - 1 + wire->start_offset, wire->start_offset);
    }
    if (wire->port_input && !wire->port_output)
        f << stringf("%s" "input%s %s;\n", indent.c_str(), range.c_str(), id(wire->name).c_str());
    if (!wire->port_input && wire->port_output)
        f << stringf("%s" "output%s %s;\n", indent.c_str(), range.c_str(), id(wire->name).c_str());
    if (wire->port_input && wire->port_output)
        f << stringf("%s" "inout%s %s;\n", indent.c_str(), range.c_str(), id(wire->name).c_str());
    if (reg_wires.count(wire->name))
        f << stringf("%s" "reg%s %s;\n", indent.c_str(), range.c_str(), id(wire->name).c_str());
    else if (!wire->port_input && !wire->port_output)
        f << stringf("%s" "wire%s %s;\n", indent.c_str(), range.c_str(), id(wire->name).c_str());
#endif
}

void dump_memory(std::ostream &f, std::string indent, RTLIL::Memory *memory)
{
    dump_attributes(f, indent, memory->attributes);
    f << stringf("%s" "reg [%d:0] %s [%d:0];\n", indent.c_str(), memory->width-1, id(memory->name).c_str(), memory->size-1);
}

void dump_cell_expr_port(std::ostream &f, RTLIL::Cell *cell, std::string port, bool gen_signed = true)
{
    if (gen_signed && cell->parameters.count("\\" + port + "_SIGNED") > 0 && cell->parameters["\\" + port + "_SIGNED"].as_bool()) {
        f << stringf("$signed(");
        dump_sigspec(f, cell->getPort("\\" + port));
        f << stringf(")");
    } else
        dump_sigspec(f, cell->getPort("\\" + port));
}

std::string cellname(RTLIL::Cell *cell)
{
    if (!norename && cell->name[0] == '$' && reg_ct.count(cell->type) && cell->hasPort("\\Q"))
    {
        RTLIL::SigSpec sig = cell->getPort("\\Q");
        if (GetSize(sig) != 1 || sig.is_fully_const())
            goto no_special_reg_name;

        RTLIL::Wire *wire = sig[0].wire;

        if (wire->name[0] != '\\')
            goto no_special_reg_name;

        std::string cell_name = wire->name.str();

        size_t pos = cell_name.find('[');
        if (pos != std::string::npos)
            cell_name = cell_name.substr(0, pos) + "_reg" + cell_name.substr(pos);
        else
            cell_name = cell_name + "_reg";

        if (wire->width != 1)
            cell_name += stringf("[%d]", wire->start_offset + sig[0].offset);

        if (active_module && active_module->count_id(cell_name) > 0)
                goto no_special_reg_name;

        return id(cell_name);
    }
    else
    {
no_special_reg_name:
        return id(cell->name).c_str();
    }
}

void dump_cell_expr_uniop(std::ostream &f, std::string indent, RTLIL::Cell *cell, std::string op)
{
    f << stringf("%s" "assign ", indent.c_str());
    dump_sigspec(f, cell->getPort("\\Y"));
    f << stringf(" = %s ", op.c_str());
    dump_attributes(f, "", cell->attributes, ' ');
    dump_cell_expr_port(f, cell, "A", true);
    f << stringf(";\n");
}

void dump_cell_expr_binop(std::ostream &f, std::string indent, RTLIL::Cell *cell, std::string op)
{
    f << stringf("%s" "assign ", indent.c_str());
    dump_sigspec(f, cell->getPort("\\Y"));
    f << stringf(" = ");
    dump_cell_expr_port(f, cell, "A", true);
    f << stringf(" %s ", op.c_str());
    dump_attributes(f, "", cell->attributes, ' ');
    dump_cell_expr_port(f, cell, "B", true);
    f << stringf(";\n");
}

bool dump_cell_expr(std::ostream &f, std::string indent, RTLIL::Cell *cell)
{
    if (cell->type == "$_NOT_") {
        f << stringf("%s" "assign ", indent.c_str());
        dump_sigspec(f, cell->getPort("\\Y"));
        f << stringf(" = ");
        f << stringf("~");
        dump_attributes(f, "", cell->attributes, ' ');
        dump_cell_expr_port(f, cell, "A", false);
        f << stringf(";\n");
        return true;
    }

    if (cell->type.in("$_AND_", "$_NAND_", "$_OR_", "$_NOR_", "$_XOR_", "$_XNOR_")) {
        f << stringf("%s" "assign ", indent.c_str());
        dump_sigspec(f, cell->getPort("\\Y"));
        f << stringf(" = ");
        if (cell->type.in("$_NAND_", "$_NOR_", "$_XNOR_"))
            f << stringf("~(");
        dump_cell_expr_port(f, cell, "A", false);
        f << stringf(" ");
        if (cell->type.in("$_AND_", "$_NAND_"))
            f << stringf("&");
        if (cell->type.in("$_OR_", "$_NOR_"))
            f << stringf("|");
        if (cell->type.in("$_XOR_", "$_XNOR_"))
            f << stringf("^");
        dump_attributes(f, "", cell->attributes, ' ');
        f << stringf(" ");
        dump_cell_expr_port(f, cell, "B", false);
        if (cell->type.in("$_NAND_", "$_NOR_", "$_XNOR_"))
            f << stringf(")");
        f << stringf(";\n");
        return true;
    }

    if (cell->type == "$_MUX_") {
        f << stringf("%s" "assign ", indent.c_str());
        dump_sigspec(f, cell->getPort("\\Y"));
        f << stringf(" = ");
        dump_cell_expr_port(f, cell, "S", false);
        f << stringf(" ? ");
        dump_attributes(f, "", cell->attributes, ' ');
        dump_cell_expr_port(f, cell, "B", false);
        f << stringf(" : ");
        dump_cell_expr_port(f, cell, "A", false);
        f << stringf(";\n");
        return true;
    }

    if (cell->type.in("$_AOI3_", "$_OAI3_")) {
        f << stringf("%s" "assign ", indent.c_str());
        dump_sigspec(f, cell->getPort("\\Y"));
        f << stringf(" = ~((");
        dump_cell_expr_port(f, cell, "A", false);
        f << stringf(cell->type == "$_AOI3_" ? " & " : " | ");
        dump_cell_expr_port(f, cell, "B", false);
        f << stringf(cell->type == "$_AOI3_" ? ") |" : ") &");
        dump_attributes(f, "", cell->attributes, ' ');
        f << stringf(" ");
        dump_cell_expr_port(f, cell, "C", false);
        f << stringf(");\n");
        return true;
    }

    if (cell->type.in("$_AOI4_", "$_OAI4_")) {
        f << stringf("%s" "assign ", indent.c_str());
        dump_sigspec(f, cell->getPort("\\Y"));
        f << stringf(" = ~((");
        dump_cell_expr_port(f, cell, "A", false);
        f << stringf(cell->type == "$_AOI4_" ? " & " : " | ");
        dump_cell_expr_port(f, cell, "B", false);
        f << stringf(cell->type == "$_AOI4_" ? ") |" : ") &");
        dump_attributes(f, "", cell->attributes, ' ');
        f << stringf(" (");
        dump_cell_expr_port(f, cell, "C", false);
        f << stringf(cell->type == "$_AOI4_" ? " & " : " | ");
        dump_cell_expr_port(f, cell, "D", false);
        f << stringf("));\n");
        return true;
    }

    if (cell->type.substr(0, 6) == "$_DFF_")
    {
        std::string reg_name = cellname(cell);
        bool out_is_reg_wire = is_reg_wire(cell->getPort("\\Q"), reg_name);

        if (!out_is_reg_wire)
            f << stringf("%s" "reg %s;\n", indent.c_str(), reg_name.c_str());

        dump_attributes(f, indent, cell->attributes);
        f << stringf("%s" "always @(%sedge ", indent.c_str(), cell->type[6] == 'P' ? "pos" : "neg");
        dump_sigspec(f, cell->getPort("\\C"));
        if (cell->type[7] != '_') {
            f << stringf(" or %sedge ", cell->type[7] == 'P' ? "pos" : "neg");
            dump_sigspec(f, cell->getPort("\\R"));
        }
        f << stringf(")\n");

        if (cell->type[7] != '_') {
            f << stringf("%s" "  if (%s", indent.c_str(), cell->type[7] == 'P' ? "" : "!");
            dump_sigspec(f, cell->getPort("\\R"));
            f << stringf(")\n");
            f << stringf("%s" "    %s <= %c;\n", indent.c_str(), reg_name.c_str(), cell->type[8]);
            f << stringf("%s" "  else\n", indent.c_str());
        }

        f << stringf("%s" "    %s <= ", indent.c_str(), reg_name.c_str());
        dump_cell_expr_port(f, cell, "D", false);
        f << stringf(";\n");

        if (!out_is_reg_wire) {
            f << stringf("%s" "assign ", indent.c_str());
            dump_sigspec(f, cell->getPort("\\Q"));
            f << stringf(" = %s;\n", reg_name.c_str());
        }

        return true;
    }

    if (cell->type.substr(0, 8) == "$_DFFSR_")
    {
        char pol_c = cell->type[8], pol_s = cell->type[9], pol_r = cell->type[10];

        std::string reg_name = cellname(cell);
        bool out_is_reg_wire = is_reg_wire(cell->getPort("\\Q"), reg_name);

        if (!out_is_reg_wire)
            f << stringf("%s" "reg %s;\n", indent.c_str(), reg_name.c_str());

        dump_attributes(f, indent, cell->attributes);
        f << stringf("%s" "always @(%sedge ", indent.c_str(), pol_c == 'P' ? "pos" : "neg");
        dump_sigspec(f, cell->getPort("\\C"));
        f << stringf(" or %sedge ", pol_s == 'P' ? "pos" : "neg");
        dump_sigspec(f, cell->getPort("\\S"));
        f << stringf(" or %sedge ", pol_r == 'P' ? "pos" : "neg");
        dump_sigspec(f, cell->getPort("\\R"));
        f << stringf(")\n");

        f << stringf("%s" "  if (%s", indent.c_str(), pol_r == 'P' ? "" : "!");
        dump_sigspec(f, cell->getPort("\\R"));
        f << stringf(")\n");
        f << stringf("%s" "    %s <= 0;\n", indent.c_str(), reg_name.c_str());

        f << stringf("%s" "  else if (%s", indent.c_str(), pol_s == 'P' ? "" : "!");
        dump_sigspec(f, cell->getPort("\\S"));
        f << stringf(")\n");
        f << stringf("%s" "    %s <= 1;\n", indent.c_str(), reg_name.c_str());

        f << stringf("%s" "  else\n", indent.c_str());
        f << stringf("%s" "    %s <= ", indent.c_str(), reg_name.c_str());
        dump_cell_expr_port(f, cell, "D", false);
        f << stringf(";\n");

        if (!out_is_reg_wire) {
            f << stringf("%s" "assign ", indent.c_str());
            dump_sigspec(f, cell->getPort("\\Q"));
            f << stringf(" = %s;\n", reg_name.c_str());
        }

        return true;
    }

#define HANDLE_UNIOP(_type, _operator) \
    if (cell->type ==_type) { dump_cell_expr_uniop(f, indent, cell, _operator); return true; }
#define HANDLE_BINOP(_type, _operator) \
    if (cell->type ==_type) { dump_cell_expr_binop(f, indent, cell, _operator); return true; }

    HANDLE_UNIOP("$not", "~")
    HANDLE_UNIOP("$pos", "+")
    HANDLE_UNIOP("$neg", "-")

    HANDLE_BINOP("$and",  "&")
    HANDLE_BINOP("$or",   "|")
    HANDLE_BINOP("$xor",  "^")
    HANDLE_BINOP("$xnor", "~^")

    HANDLE_UNIOP("$reduce_and",  "&")
    HANDLE_UNIOP("$reduce_or",   "|")
    HANDLE_UNIOP("$reduce_xor",  "^")
    HANDLE_UNIOP("$reduce_xnor", "~^")
    HANDLE_UNIOP("$reduce_bool", "|")

    HANDLE_BINOP("$shl",  "<<")
    HANDLE_BINOP("$shr",  ">>")
    HANDLE_BINOP("$sshl", "<<<")
    HANDLE_BINOP("$sshr", ">>>")

    HANDLE_BINOP("$lt",  "<")
    HANDLE_BINOP("$le",  "<=")
    HANDLE_BINOP("$eq",  "==")
    HANDLE_BINOP("$ne",  "!=")
    HANDLE_BINOP("$eqx", "===")
    HANDLE_BINOP("$nex", "!==")
    HANDLE_BINOP("$ge",  ">=")
    HANDLE_BINOP("$gt",  ">")

    HANDLE_BINOP("$add", "+")
    HANDLE_BINOP("$sub", "-")
    HANDLE_BINOP("$mul", "*")
    HANDLE_BINOP("$div", "/")
    HANDLE_BINOP("$mod", "%")
    HANDLE_BINOP("$pow", "**")

    HANDLE_UNIOP("$logic_not", "!")
    HANDLE_BINOP("$logic_and", "&&")
    HANDLE_BINOP("$logic_or",  "||")

#undef HANDLE_UNIOP
#undef HANDLE_BINOP

    if (cell->type == "$mux")
    {
        f << stringf("%s" "assign ", indent.c_str());
        dump_sigspec(f, cell->getPort("\\Y"));
        f << stringf(" = ");
        dump_sigspec(f, cell->getPort("\\S"));
        f << stringf(" ? ");
        dump_attributes(f, "", cell->attributes, ' ');
        dump_sigspec(f, cell->getPort("\\B"));
        f << stringf(" : ");
        dump_sigspec(f, cell->getPort("\\A"));
        f << stringf(";\n");
        return true;
    }

    if (cell->type == "$pmux" || cell->type == "$pmux_safe")
    {
        int width = cell->parameters["\\WIDTH"].as_int();
        int s_width = cell->getPort("\\S").size();
        std::string func_name = cellname(cell);

        f << stringf("%s" "function [%d:0] %s;\n", indent.c_str(), width-1, func_name.c_str());
        f << stringf("%s" "  input [%d:0] a;\n", indent.c_str(), width-1);
        f << stringf("%s" "  input [%d:0] b;\n", indent.c_str(), s_width*width-1);
        f << stringf("%s" "  input [%d:0] s;\n", indent.c_str(), s_width-1);

        dump_attributes(f, indent + "  ", cell->attributes);
        if (cell->type != "$pmux_safe" && !noattr)
            f << stringf("%s" "  (* parallel_case *)\n", indent.c_str());
        f << stringf("%s" "  casez (s)", indent.c_str());
        if (cell->type != "$pmux_safe")
            f << stringf(noattr ? " // synopsys parallel_case\n" : "\n");

        for (int i = 0; i < s_width; i++)
        {
            f << stringf("%s" "    %d'b", indent.c_str(), s_width);

            for (int j = s_width-1; j >= 0; j--)
                f << stringf("%c", j == i ? '1' : cell->type == "$pmux_safe" ? '0' : '?');

            f << stringf(":\n");
            f << stringf("%s" "      %s = b[%d:%d];\n", indent.c_str(), func_name.c_str(), (i+1)*width-1, i*width);
        }

        f << stringf("%s" "    default:\n", indent.c_str());
        f << stringf("%s" "      %s = a;\n", indent.c_str(), func_name.c_str());

        f << stringf("%s" "  endcase\n", indent.c_str());
        f << stringf("%s" "endfunction\n", indent.c_str());

        f << stringf("%s" "assign ", indent.c_str());
        dump_sigspec(f, cell->getPort("\\Y"));
        f << stringf(" = %s(", func_name.c_str());
        dump_sigspec(f, cell->getPort("\\A"));
        f << stringf(", ");
        dump_sigspec(f, cell->getPort("\\B"));
        f << stringf(", ");
        dump_sigspec(f, cell->getPort("\\S"));
        f << stringf(");\n");
        return true;
    }

    if (cell->type == "$slice")
    {
        f << stringf("%s" "assign ", indent.c_str());
        dump_sigspec(f, cell->getPort("\\Y"));
        f << stringf(" = ");
        dump_sigspec(f, cell->getPort("\\A"));
        f << stringf(" >> %d;\n", cell->parameters.at("\\OFFSET").as_int());
        return true;
    }

    if (cell->type == "$concat")
    {
        f << stringf("%s" "assign ", indent.c_str());
        dump_sigspec(f, cell->getPort("\\Y"));
        f << stringf(" = { ");
        dump_sigspec(f, cell->getPort("\\B"));
        f << stringf(" , ");
        dump_sigspec(f, cell->getPort("\\A"));
        f << stringf(" };\n");
        return true;
    }

    if (cell->type == "$dff" || cell->type == "$adff")
    {
        RTLIL::SigSpec sig_clk, sig_arst, val_arst;
        bool pol_clk, pol_arst = false;

        sig_clk = cell->getPort("\\CLK");
        pol_clk = cell->parameters["\\CLK_POLARITY"].as_bool();

        if (cell->type == "$adff") {
            sig_arst = cell->getPort("\\ARST");
            pol_arst = cell->parameters["\\ARST_POLARITY"].as_bool();
            val_arst = RTLIL::SigSpec(cell->parameters["\\ARST_VALUE"]);
        }

        std::string reg_name = cellname(cell);
        bool out_is_reg_wire = is_reg_wire(cell->getPort("\\Q"), reg_name);

        if (!out_is_reg_wire)
            f << stringf("%s" "reg [%d:0] %s;\n", indent.c_str(), cell->parameters["\\WIDTH"].as_int()-1, reg_name.c_str());

        f << stringf("%s" "always @(%sedge ", indent.c_str(), pol_clk ? "pos" : "neg");
        dump_sigspec(f, sig_clk);
        if (cell->type == "$adff") {
            f << stringf(" or %sedge ", pol_arst ? "pos" : "neg");
            dump_sigspec(f, sig_arst);
        }
        f << stringf(")\n");

        if (cell->type == "$adff") {
            f << stringf("%s" "  if (%s", indent.c_str(), pol_arst ? "" : "!");
            dump_sigspec(f, sig_arst);
            f << stringf(")\n");
            f << stringf("%s" "    %s <= ", indent.c_str(), reg_name.c_str());
            dump_sigspec(f, val_arst);
            f << stringf(";\n");
            f << stringf("%s" "  else\n", indent.c_str());
        }

        f << stringf("%s" "    %s <= ", indent.c_str(), reg_name.c_str());
        dump_cell_expr_port(f, cell, "D", false);
        f << stringf(";\n");

        if (!out_is_reg_wire) {
            f << stringf("%s" "assign ", indent.c_str());
            dump_sigspec(f, cell->getPort("\\Q"));
            f << stringf(" = %s;\n", reg_name.c_str());
        }

        return true;
    }

    // FIXME: $_SR_[PN][PN]_, $_DLATCH_[PN]_, $_DLATCHSR_[PN][PN][PN]_
    // FIXME: $sr, $dffsr, $dlatch, $memrd, $memwr, $mem, $fsm

    return false;
}

void dump_cell(std::ostream &f, std::string indent, RTLIL::Cell *cell)
{
    if (cell->type[0] == '$' && !noexpr) {
        if (dump_cell_expr(f, indent, cell))
            return;
    }

    dump_attributes(f, indent, cell->attributes);
    f << stringf("%s" "%s", indent.c_str(), id(cell->type, false).c_str());

    if (cell->parameters.size() > 0) {
        f << stringf(" #(");
        for (auto it = cell->parameters.begin(); it != cell->parameters.end(); it++) {
            if (it != cell->parameters.begin())
                f << stringf(",");
            f << stringf("\n%s  .%s(", indent.c_str(), id(it->first).c_str());
            bool is_signed = (it->second.flags & RTLIL::CONST_FLAG_SIGNED) != 0;
            dump_const(f, it->second, -1, 0, !is_signed, is_signed);
            f << stringf(")");
        }
        f << stringf("\n%s" ")", indent.c_str());
    }

    std::string cell_name = cellname(cell);
    if (cell_name != id(cell->name))
        f << stringf(" %s /* %s */ (", cell_name.c_str(), id(cell->name).c_str());
    else
        f << stringf(" %s (", cell_name.c_str());

    bool first_arg = true;
    std::set<RTLIL::IdString> numbered_ports;
    for (int i = 1; true; i++) {
        char str[16];
        snprintf(str, 16, "$%d", i);
        for (auto it = cell->connections().begin(); it != cell->connections().end(); it++) {
            if (it->first != str)
                continue;
            if (!first_arg)
                f << stringf(",");
            first_arg = false;
            f << stringf("\n%s  ", indent.c_str());
            dump_sigspec(f, it->second);
            numbered_ports.insert(it->first);
            goto found_numbered_port;
        }
        break;
    found_numbered_port:;
    }
    for (auto it = cell->connections().begin(); it != cell->connections().end(); it++) {
        if (numbered_ports.count(it->first))
            continue;
        if (!first_arg)
            f << stringf(",");
        first_arg = false;
        f << stringf("\n%s  .%s(", indent.c_str(), id(it->first).c_str());
        if (it->second.size() > 0)
            dump_sigspec(f, it->second);
        f << stringf(")");
    }
    f << stringf("\n%s" ");\n", indent.c_str());
}

void dump_conn(std::ostream &f, std::string indent, const RTLIL::SigSpec &left, const RTLIL::SigSpec &right)
{
    f << stringf("%s" "assign ", indent.c_str());
    dump_sigspec(f, left);
    f << stringf(" = ");
    dump_sigspec(f, right);
    f << stringf(";\n");
}

void dump_proc_switch(std::ostream &f, std::string indent, RTLIL::SwitchRule *sw);

void dump_case_body(std::ostream &f, std::string indent, RTLIL::CaseRule *cs, bool omit_trailing_begin = false)
{
    int number_of_stmts = cs->switches.size() + cs->actions.size();

    if (!omit_trailing_begin && number_of_stmts >= 2)
        f << stringf("%s" "begin\n", indent.c_str());

    for (auto it = cs->actions.begin(); it != cs->actions.end(); it++) {
        if (it->first.size() == 0)
            continue;
        f << stringf("%s  ", indent.c_str());
        dump_sigspec(f, it->first);
        f << stringf(" = ");
        dump_sigspec(f, it->second);
        f << stringf(";\n");
    }

    for (auto it = cs->switches.begin(); it != cs->switches.end(); it++)
        dump_proc_switch(f, indent + "  ", *it);

    if (!omit_trailing_begin && number_of_stmts == 0)
        f << stringf("%s  /* empty */;\n", indent.c_str());

    if (omit_trailing_begin || number_of_stmts >= 2)
        f << stringf("%s" "end\n", indent.c_str());
}

void dump_proc_switch(std::ostream &f, std::string indent, RTLIL::SwitchRule *sw)
{
    if (sw->signal.size() == 0) {
        f << stringf("%s" "begin\n", indent.c_str());
        for (auto it = sw->cases.begin(); it != sw->cases.end(); it++) {
            if ((*it)->compare.size() == 0)
                dump_case_body(f, indent + "  ", *it);
        }
        f << stringf("%s" "end\n", indent.c_str());
        return;
    }

    f << stringf("%s" "casez (", indent.c_str());
    dump_sigspec(f, sw->signal);
    f << stringf(")\n");

    for (auto it = sw->cases.begin(); it != sw->cases.end(); it++) {
        f << stringf("%s  ", indent.c_str());
        if ((*it)->compare.size() == 0)
            f << stringf("default");
        else {
            for (size_t i = 0; i < (*it)->compare.size(); i++) {
                if (i > 0)
                    f << stringf(", ");
                dump_sigspec(f, (*it)->compare[i]);
            }
        }
        f << stringf(":\n");
        dump_case_body(f, indent + "    ", *it);
    }

    f << stringf("%s" "endcase\n", indent.c_str());
}

void case_body_find_regs(RTLIL::CaseRule *cs)
{
    for (auto it = cs->switches.begin(); it != cs->switches.end(); it++)
    for (auto it2 = (*it)->cases.begin(); it2 != (*it)->cases.end(); it2++)
        case_body_find_regs(*it2);

    for (auto it = cs->actions.begin(); it != cs->actions.end(); it++) {
        for (auto &c : it->first.chunks())
            if (c.wire != NULL)
                reg_wires.insert(c.wire->name);
    }
}

void dump_process(std::ostream &f, std::string indent, RTLIL::Process *proc, bool find_regs = false)
{
    if (find_regs) {
        case_body_find_regs(&proc->root_case);
        for (auto it = proc->syncs.begin(); it != proc->syncs.end(); it++)
        for (auto it2 = (*it)->actions.begin(); it2 != (*it)->actions.end(); it2++) {
            for (auto &c : it2->first.chunks())
                if (c.wire != NULL)
                    reg_wires.insert(c.wire->name);
        }
        return;
    }

    f << stringf("%s" "always @* begin\n", indent.c_str());
    dump_case_body(f, indent, &proc->root_case, true);

    std::string backup_indent = indent;

    for (size_t i = 0; i < proc->syncs.size(); i++)
    {
        RTLIL::SyncRule *sync = proc->syncs[i];
        indent = backup_indent;

        if (sync->type == RTLIL::STa) {
            f << stringf("%s" "always @* begin\n", indent.c_str());
        } else {
            f << stringf("%s" "always @(", indent.c_str());
            if (sync->type == RTLIL::STp || sync->type == RTLIL::ST1)
                f << stringf("posedge ");
            if (sync->type == RTLIL::STn || sync->type == RTLIL::ST0)
                f << stringf("negedge ");
            dump_sigspec(f, sync->signal);
            f << stringf(") begin\n");
        }
        std::string ends = indent + "end\n";
        indent += "  ";

        if (sync->type == RTLIL::ST0 || sync->type == RTLIL::ST1) {
            f << stringf("%s" "if (%s", indent.c_str(), sync->type == RTLIL::ST0 ? "!" : "");
            dump_sigspec(f, sync->signal);
            f << stringf(") begin\n");
            ends = indent + "end\n" + ends;
            indent += "  ";
        }

        if (sync->type == RTLIL::STp || sync->type == RTLIL::STn) {
            for (size_t j = 0; j < proc->syncs.size(); j++) {
                RTLIL::SyncRule *sync2 = proc->syncs[j];
                if (sync2->type == RTLIL::ST0 || sync2->type == RTLIL::ST1) {
                    f << stringf("%s" "if (%s", indent.c_str(), sync2->type == RTLIL::ST1 ? "!" : "");
                    dump_sigspec(f, sync2->signal);
                    f << stringf(") begin\n");
                    ends = indent + "end\n" + ends;
                    indent += "  ";
                }
            }
        }

        for (auto it = sync->actions.begin(); it != sync->actions.end(); it++) {
            if (it->first.size() == 0)
                continue;
            f << stringf("%s  ", indent.c_str());
            dump_sigspec(f, it->first);
            f << stringf(" <= ");
            dump_sigspec(f, it->second);
            f << stringf(";\n");
        }

        f << stringf("%s", ends.c_str());
    }
}

void dump_module(std::ostream &f, std::string indent, RTLIL::Module *module)
{
    reg_wires.clear();
    reset_auto_counter(module);
    active_module = module;

    f << stringf("\n");
    for (auto it = module->processes.begin(); it != module->processes.end(); it++)
        dump_process(f, indent + "  ", it->second, true);

    if (!noexpr)
    {
        std::set<std::pair<RTLIL::Wire*,int>> reg_bits;
        for (auto &it : module->cells_)
        {
            RTLIL::Cell *cell = it.second;
            if (!reg_ct.count(cell->type) || !cell->hasPort("\\Q"))
                continue;

            RTLIL::SigSpec sig = cell->getPort("\\Q");

            if (sig.is_chunk()) {
                RTLIL::SigChunk chunk = sig.as_chunk();
                if (chunk.wire != NULL)
                    for (int i = 0; i < chunk.width; i++)
                        reg_bits.insert(std::pair<RTLIL::Wire*,int>(chunk.wire, chunk.offset+i));
            }
        }
        for (auto &it : module->wires_)
        {
            RTLIL::Wire *wire = it.second;
            for (int i = 0; i < wire->width; i++)
                if (reg_bits.count(std::pair<RTLIL::Wire*,int>(wire, i)) == 0)
                    goto this_wire_aint_reg;
            if (wire->width)
                reg_wires.insert(wire->name);
        this_wire_aint_reg:;
        }
    }

    dump_attributes(f, indent, module->attributes);
    f << stringf("%s" "module %s(", indent.c_str(), id(module->name, false).c_str());
    bool keep_running = true;
    for (int port_id = 1; keep_running; port_id++) {
        keep_running = false;
        for (auto it = module->wires_.begin(); it != module->wires_.end(); it++) {
            RTLIL::Wire *wire = it->second;
            if (wire->port_id == port_id) {
                if (port_id != 1)
                    f << stringf(", ");
                f << stringf("%s", id(wire->name).c_str());
                keep_running = true;
                continue;
            }
        }
    }
    f << stringf(");\n");

    for (auto it = module->wires_.begin(); it != module->wires_.end(); it++)
        dump_wire(f, indent + "  ", it->second);

    for (auto it = module->memories.begin(); it != module->memories.end(); it++)
        dump_memory(f, indent + "  ", it->second);

    for (auto it = module->cells_.begin(); it != module->cells_.end(); it++)
        dump_cell(f, indent + "  ", it->second);

    for (auto it = module->processes.begin(); it != module->processes.end(); it++)
        dump_process(f, indent + "  ", it->second);

    for (auto it = module->connections().begin(); it != module->connections().end(); it++)
        dump_conn(f, indent + "  ", it->first, it->second);

    f << stringf("%s" "endmodule\n", indent.c_str());
    active_module = NULL;
}

struct VerilogBackend : public Backend {
    VerilogBackend() : Backend("verilog", "write design to verilog file") { }
    virtual void help()
    {
        //   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
        log("\n");
        log("    write_verilog [options] [filename]\n");
        log("\n");
        log("Write the current design to a verilog file.\n");
        log("\n");
        log("    -norename\n");
        log("        without this option all internal object names (the ones with a dollar\n");
        log("        instead of a backslash prefix) are changed to short names in the\n");
        log("        format '_<number>_'.\n");
        log("\n");
        log("    -noattr\n");
        log("        with this option no attributes are included in the output\n");
        log("\n");
        log("    -attr2comment\n");
        log("        with this option attributes are included as comments in the output\n");
        log("\n");
        log("    -noexpr\n");
        log("        without this option all internal cells are converted to verilog\n");
        log("        expressions.\n");
        log("\n");
        log("    -blackboxes\n");
        log("        usually modules with the 'blackbox' attribute are ignored. with\n");
        log("        this option set only the modules with the 'blackbox' attribute\n");
        log("        are written to the output file.\n");
        log("\n");
        log("    -selected\n");
        log("        only write selected modules. modules must be selected entirely or\n");
        log("        not at all.\n");
        log("\n");
    }
    virtual void execute(std::ostream *&f, std::string filename, std::vector<std::string> args, RTLIL::Design *design)
    {
        log_header("Executing Verilog backend.\n");

        norename = false;
        noattr = false;
        attr2comment = false;
        noexpr = false;

        bool blackboxes = false;
        bool selected = false;

        reg_ct.clear();

        reg_ct.insert("$dff");
        reg_ct.insert("$adff");

        reg_ct.insert("$_DFF_N_");
        reg_ct.insert("$_DFF_P_");

        reg_ct.insert("$_DFF_NN0_");
        reg_ct.insert("$_DFF_NN1_");
        reg_ct.insert("$_DFF_NP0_");
        reg_ct.insert("$_DFF_NP1_");
        reg_ct.insert("$_DFF_PN0_");
        reg_ct.insert("$_DFF_PN1_");
        reg_ct.insert("$_DFF_PP0_");
        reg_ct.insert("$_DFF_PP1_");

        reg_ct.insert("$_DFFSR_NNN_");
        reg_ct.insert("$_DFFSR_NNP_");
        reg_ct.insert("$_DFFSR_NPN_");
        reg_ct.insert("$_DFFSR_NPP_");
        reg_ct.insert("$_DFFSR_PNN_");
        reg_ct.insert("$_DFFSR_PNP_");
        reg_ct.insert("$_DFFSR_PPN_");
        reg_ct.insert("$_DFFSR_PPP_");

        size_t argidx;
        for (argidx = 1; argidx < args.size(); argidx++) {
            std::string arg = args[argidx];
            if (arg == "-norename") {
                norename = true;
                continue;
            }
            if (arg == "-noattr") {
                noattr = true;
                continue;
            }
            if (arg == "-attr2comment") {
                attr2comment = true;
                continue;
            }
            if (arg == "-noexpr") {
                noexpr = true;
                continue;
            }
            if (arg == "-blackboxes") {
                blackboxes = true;
                continue;
            }
            if (arg == "-selected") {
                selected = true;
                continue;
            }
            break;
        }
        extra_args(f, filename, args, argidx);

        *f << stringf("/* Generated by %s */\n", yosys_version_str);
        for (auto it = design->modules_.begin(); it != design->modules_.end(); it++) {
            if (it->second->get_bool_attribute("\\blackbox") != blackboxes)
                continue;
            if (selected && !design->selected_whole_module(it->first)) {
                if (design->selected_module(it->first))
                    log_cmd_error("Can't handle partially selected module %s!\n", RTLIL::id2cstr(it->first));
                continue;
            }
            log("Dumping module `%s'.\n", it->first.c_str());
            dump_module(*f, "", it->second);
        }

        reg_ct.clear();
    }
} VerilogBackend;

PRIVATE_NAMESPACE_END