nextpnr/frontend/frontend_base.h
David Shah fffc3b8447 frontend/base: Top module handling
Signed-off-by: David Shah <dave@ds0.me>
2019-12-27 10:44:29 +00:00

192 lines
7.8 KiB
C++

/*
* nextpnr -- Next Generation Place and Route
*
* Copyright (C) 2019 David Shah <dave@ds0.me>
*
* 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.
*
*/
/*
* Generic Frontend Framework
*
* This is designed to make it possible to build frontends for parsing any format isomorphic to Yosys JSON [1]
* with maximal inlining and minimal need for overhead such as runtime polymorphism or extra wrapper types.
*
* [1] http://www.clifford.at/yosys/cmd_write_json.html
*
* The frontend should implement a class referred to as FrontendType that defines the following type(def)s and
* functions:
*
* Types:
* ModuleDataType: corresponds to a single entry in "modules"
* ModulePortDataType: corresponds to a single entry in "ports" of a module
* CellDataType: corresponds to a single entry in "cells"
* NetnameDataType: corresponds to a single entry in "netnames"
* BitVectorDataType: corresponds to a signal/constant bit vector (e.g. a "connections" field)
*
* Functions:
*
* void foreach_module(Func);
* calls Func(const std::string &name, const ModuleDataType &mod);
* for each module in the netlist
*
* void foreach_port(const ModuleDataType &mod, Func);
* calls Func(const std::string &name, const ModulePortDataType &port);
* for each port of mod
*
* void foreach_cell(const ModuleDataType &mod, Func);
* calls Func(const std::string &name, const CellDataType &cell);
* for each cell of mod
*
* void foreach_netname(const ModuleDataType &mod, Func);
* calls Func(const std::string &name, const NetnameDataType &cell);
* for each netname entry of mod
*
* PortType get_port_dir(const ModulePortDataType &port);
* gets the PortType direction of a module port
*
* int get_port_offset(const ModulePortDataType &port);
* gets the start bit number of a port
*
* bool is_port_upto(const ModulePortDataType &port);
* returns true if a port is an "upto" type port
*
* const BitVectorDataType &get_port_bits(const ModulePortDataType &port);
* gets the bit vector of a module port
*
* const std::string& get_cell_type(const CellDataType &cell);
* gets the type of a cell
*
* void foreach_attr(const {ModuleDataType|CellDataType|ModulePortDataType|NetnameDataType} &obj, Func);
* calls Func(const std::string &name, const Property &value);
* for each attribute on a module, cell, module port or net
*
* void foreach_param(const CellDataType &obj, Func);
* calls Func(const std::string &name, const Property &value);
* for each parameter of a cell
*
* void foreach_port_dir(const CellDataType &cell, Func);
* calls Func(const std::string &name, PortType dir);
* for each port direction of a cell
*
* void foreach_port_conn(const CellDataType &cell, Func);
* calls Func(const std::string &name, const BitVectorDataType &conn);
* for each port connection of a cell
*
* const BitVectorDataType &get_net_bits(const NetnameDataType &net);
* gets the BitVector corresponding to the bits entry of a netname field
*
* int get_vector_length(const BitVectorDataType &bits);
* gets the length of a BitVector
*
* bool is_vector_bit_constant(const BitVectorDataType &bits, int i);
* returns true if bit <i> of bits is constant
*
* char get_vector_bit_constval(const BitVectorDataType &bits, int i);
* returns a char [01xz] corresponding to the constant value of bit <i>
*
* int get_vector_bit_signal(const BitVectorDataType &bits, int i);
* returns the signal number of vector bit <i>
*
*/
#include "log.h"
#include "nextpnr.h"
NEXTPNR_NAMESPACE_BEGIN
namespace {
template <typename FrontendType> struct GenericFrontend
{
GenericFrontend(Context *ctx, const FrontendType &impl) : ctx(ctx), impl(impl) {}
Context *ctx;
const FrontendType &impl;
using mod_dat_t = typename FrontendType::ModuleDataType;
using mod_port_dat_t = typename FrontendType::ModulePortDataType;
using cell_dat_t = typename FrontendType::CellDataType;
using netname_dat_t = typename FrontendType::NetnameDataType;
using bitvector_t = typename FrontendType::BitVectorDataType;
// Used for hierarchy resolution
struct ModuleInfo
{
mod_dat_t *mod_data;
bool is_top = false, is_blackbox = false, is_whitebox = false;
inline bool is_box() const { return is_blackbox || is_whitebox; }
std::unordered_set<IdString> instantiated_celltypes;
};
std::unordered_map<IdString, ModuleInfo> mods;
IdString top;
// Process the list of modules and determine
// the top module
void find_top_module()
{
impl.foreach_module([&](const std::string &name, const mod_dat_t &mod) {
IdString mod_id = ctx->id(name);
auto &mi = mods[mod_id];
mi.mod_data = &mod;
impl.foreach_attr(mod, [&](const std::string &name, const Property &value) {
if (name == "top")
mi.is_top = (value.intval != 0);
else if (name == "blackbox")
mi.is_blackbox = (value.intval != 0);
else if (name == "whitebox")
mi.is_whitebox = (value.intval != 0);
});
impl.foreach_cell(mod, [&](const std::string &name, const cell_dat_t &cell) {
mi.instantiated_cells.insert(ctx->id(impl.get_cell_type(cell)));
});
});
// First of all, see if a top module has been manually specified
if (ctx->settings.count(ctx->id("frontend/top"))) {
IdString user_top = ctx->id(ctx->settings.at(ctx->id("frontend/top")).as_string());
if (!mods.count(user_top))
log_error("Top module '%s' not found!\n", ctx->nameOf(user_top));
top = user_top;
return;
}
// If not, look for a module with the top attribute set
IdString top_by_attr;
for (auto &mod : mods) {
if (mod.second.is_top && !mod.second.is_box()) {
if (top_by_attr != IdString())
log_error("Found multiple modules with (* top *) set (including %s and %s).\n",
ctx->nameOf(top_by_attr), ctx->nameOf(mod.first));
top_by_attr = mod.first;
}
}
if (top_by_attr != IdString()) {
top = top_by_attr;
return;
}
// Finally, attempt to autodetect the top module using hierarchy
// (a module that is not a box and is not used as a cell by any other module)
std::unordered_set<IdString> candidate_top;
for (auto &mod : mods)
if (!mod.second.is_box())
candidate_top.insert(mod.first);
for (auto &mod : mods)
for (auto &c : mod.second.instantiated_celltypes)
candidate_top.erase(c);
if (candidate_top.size() != 1)
log_error("Failed to autodetect top module, please specify using --top.\n");
top = *(candidate_top.begin());
}
};
} // namespace
template <typename FrontendType> void run_frontend(Context *ctx, const FrontendType &impl) {}
NEXTPNR_NAMESPACE_END