proc_init.cc

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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/log.h"
#include <stdlib.h>
#include <stdio.h>

USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN

void proc_get_const(RTLIL::SigSpec &sig, RTLIL::CaseRule &rule)
{
    log_assert(rule.compare.size() == 0);

    while (1) {
        RTLIL::SigSpec tmp = sig;
        for (auto &it : rule.actions)
            tmp.replace(it.first, it.second);
        if (tmp == sig)
            break;
        sig = tmp;
    }
}

void proc_init(RTLIL::Module *mod, RTLIL::Process *proc)
{
    bool found_init = false;

    for (auto &sync : proc->syncs)
        if (sync->type == RTLIL::SyncType::STi)
        {
            found_init = true;
            log("Found init rule in `%s.%s'.\n", mod->name.c_str(), proc->name.c_str());

            for (auto &action : sync->actions)
            {
                RTLIL::SigSpec lhs = action.first;
                RTLIL::SigSpec rhs = action.second;

                proc_get_const(rhs, proc->root_case);

                if (!rhs.is_fully_const())
                    log_cmd_error("Failed to get a constant init value for %s: %s\n", log_signal(lhs), log_signal(rhs));

                int offset = 0;
                for (auto &lhs_c : lhs.chunks()) {
                    if (lhs_c.wire != NULL) {
                        RTLIL::SigSpec value = rhs.extract(offset, lhs_c.width);
                        if (value.size() != lhs_c.wire->width)
                            log_cmd_error("Init value is not for the entire wire: %s = %s\n", log_signal(lhs_c), log_signal(value));
                        log("  Setting init value: %s = %s\n", log_signal(lhs_c.wire), log_signal(value));
                        lhs_c.wire->attributes["\\init"] = value.as_const();
                    }
                    offset += lhs_c.width;
                }
            }
        }

    if (found_init) {
        std::vector<RTLIL::SyncRule*> new_syncs;
        for (auto &sync : proc->syncs)
            if (sync->type == RTLIL::SyncType::STi)
                delete sync;
            else
                new_syncs.push_back(sync);
        proc->syncs.swap(new_syncs);
    }
}

struct ProcInitPass : public Pass {
    ProcInitPass() : Pass("proc_init", "convert initial block to init attributes") { }
    virtual void help()
    {
        //   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
        log("\n");
        log("    proc_init [selection]\n");
        log("\n");
        log("This pass extracts the 'init' actions from processes (generated from verilog\n");
        log("'initial' blocks) and sets the initial value to the 'init' attribute on the\n");
        log("respective wire.\n");
        log("\n");
    }
    virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
    {
        log_header("Executing PROC_INIT pass (extract init attributes).\n");

        extra_args(args, 1, design);

        for (auto mod : design->modules())
            if (design->selected(mod))
                for (auto &proc_it : mod->processes)
                    if (design->selected(mod, proc_it.second))
                        proc_init(mod, proc_it.second);
    }
} ProcInitPass;
 
PRIVATE_NAMESPACE_END