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yosys/backends/firrtl/firrtl.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/rtlil.h"
#include "kernel/register.h"
#include "kernel/sigtools.h"
#include "kernel/celltypes.h"
#include "kernel/cellaigs.h"
#include "kernel/log.h"
#include <algorithm>
#include <string>
#include <vector>
#include <cmath>
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
pool<string> used_names;
dict<IdString, string> namecache;
int autoid_counter;
typedef unsigned FDirection;
static const FDirection FD_NODIRECTION = 0x0;
static const FDirection FD_IN = 0x1;
static const FDirection FD_OUT = 0x2;
static const FDirection FD_INOUT = 0x3;
static const int FIRRTL_MAX_DSH_WIDTH_ERROR = 20; // For historic reasons, this is actually one greater than the maximum allowed shift width
// Shamelessly copied from ilang_backend.cc. Something better is surely possible here.
void dump_const(std::ostream &f, const RTLIL::Const &data, int width = -1, int offset = 0, bool autoint = true)
{
if (width < 0)
width = data.bits.size() - offset;
if ((data.flags & RTLIL::CONST_FLAG_STRING) == 0 || width != (int)data.bits.size()) {
if (width == 32 && autoint) {
int32_t val = 0;
for (int i = 0; i < width; i++) {
log_assert(offset+i < (int)data.bits.size());
switch (data.bits[offset+i]) {
case RTLIL::S0: break;
case RTLIL::S1: val |= 1 << i; break;
default: val = -1; break;
}
}
if (val >= 0) {
f << stringf("%d", val);
return;
}
}
f << stringf("%d'", width);
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("-"); break;
case RTLIL::Sm: f << stringf("m"); break;
}
}
} 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("\"");
}
}
std::string getFileinfo(dict<RTLIL::IdString, RTLIL::Const> attributes)
{
std::ostringstream fileinfo;
for (auto &it : attributes) {
if (it.first == "\\src") {
fileinfo << "@[";
dump_const(fileinfo, it.second);
fileinfo << "]";
}
}
return fileinfo.str();
}
// Get a port direction with respect to a specific module.
FDirection getPortFDirection(IdString id, Module *module)
{
Wire *wire = module->wires_.at(id);
FDirection direction = FD_NODIRECTION;
if (wire && wire->port_id)
{
if (wire->port_input)
direction |= FD_IN;
if (wire->port_output)
direction |= FD_OUT;
}
return direction;
}
string next_id()
{
string new_id;
while (1) {
new_id = stringf("_%d", autoid_counter++);
if (used_names.count(new_id) == 0) break;
}
used_names.insert(new_id);
return new_id;
}
const char *make_id(IdString id)
{
if (namecache.count(id) != 0)
return namecache.at(id).c_str();
string new_id = log_id(id);
for (int i = 0; i < GetSize(new_id); i++)
{
char &ch = new_id[i];
if ('a' <= ch && ch <= 'z') continue;
if ('A' <= ch && ch <= 'Z') continue;
if ('0' <= ch && ch <= '9' && i != 0) continue;
if ('_' == ch) continue;
ch = '_';
}
while (used_names.count(new_id) != 0)
new_id += '_';
namecache[id] = new_id;
used_names.insert(new_id);
return namecache.at(id).c_str();
}
struct FirrtlWorker
{
Module *module;
std::ostream &f;
dict<SigBit, pair<string, int>> reverse_wire_map;
string unconn_id;
RTLIL::Design *design;
std::string indent;
// Define read/write ports and memories.
// We'll collect their definitions and emit the corresponding FIRRTL definitions at the appropriate point in module construction.
// For the moment, we don't handle $readmemh or $readmemb.
// These will be part of a subsequent PR.
struct read_port {
string name;
bool clk_enable;
bool clk_parity;
bool transparent;
RTLIL::SigSpec clk;
RTLIL::SigSpec ena;
RTLIL::SigSpec addr;
read_port(string name, bool clk_enable, bool clk_parity, bool transparent, RTLIL::SigSpec clk, RTLIL::SigSpec ena, RTLIL::SigSpec addr) : name(name), clk_enable(clk_enable), clk_parity(clk_parity), transparent(transparent), clk(clk), ena(ena), addr(addr) {
// Current (3/13/2019) conventions:
// generate a constant 0 for clock and a constant 1 for enable if they are undefined.
if (!clk.is_fully_def())
this->clk = SigSpec(State::S0);
if (!ena.is_fully_def())
this->ena = SigSpec(State::S1);
}
string gen_read(const char * indent) {
string addr_expr = make_expr(addr);
string ena_expr = make_expr(ena);
string clk_expr = make_expr(clk);
string addr_str = stringf("%s%s.addr <= %s\n", indent, name.c_str(), addr_expr.c_str());
string ena_str = stringf("%s%s.en <= %s\n", indent, name.c_str(), ena_expr.c_str());
string clk_str = stringf("%s%s.clk <= asClock(%s)\n", indent, name.c_str(), clk_expr.c_str());
return addr_str + ena_str + clk_str;
}
};
struct write_port : read_port {
RTLIL::SigSpec mask;
write_port(string name, bool clk_enable, bool clk_parity, bool transparent, RTLIL::SigSpec clk, RTLIL::SigSpec ena, RTLIL::SigSpec addr, RTLIL::SigSpec mask) : read_port(name, clk_enable, clk_parity, transparent, clk, ena, addr), mask(mask) {
if (!clk.is_fully_def())
this->clk = SigSpec(RTLIL::Const(0));
if (!ena.is_fully_def())
this->ena = SigSpec(RTLIL::Const(0));
if (!mask.is_fully_def())
this->ena = SigSpec(RTLIL::Const(1));
}
string gen_read(const char * /* indent */) {
log_error("gen_read called on write_port: %s\n", name.c_str());
return stringf("gen_read called on write_port: %s\n", name.c_str());
}
string gen_write(const char * indent) {
string addr_expr = make_expr(addr);
string ena_expr = make_expr(ena);
string clk_expr = make_expr(clk);
string mask_expr = make_expr(mask);
string mask_str = stringf("%s%s.mask <= %s\n", indent, name.c_str(), mask_expr.c_str());
string addr_str = stringf("%s%s.addr <= %s\n", indent, name.c_str(), addr_expr.c_str());
string ena_str = stringf("%s%s.en <= %s\n", indent, name.c_str(), ena_expr.c_str());
string clk_str = stringf("%s%s.clk <= asClock(%s)\n", indent, name.c_str(), clk_expr.c_str());
return addr_str + ena_str + clk_str + mask_str;
}
};
/* Memories defined within this module. */
struct memory {
Cell *pCell; // for error reporting
string name; // memory name
int abits; // number of address bits
int size; // size (in units) of the memory
int width; // size (in bits) of each element
int read_latency;
int write_latency;
vector<read_port> read_ports;
vector<write_port> write_ports;
std::string init_file;
std::string init_file_srcFileSpec;
string srcLine;
memory(Cell *pCell, string name, int abits, int size, int width) : pCell(pCell), name(name), abits(abits), size(size), width(width), read_latency(0), write_latency(1), init_file(""), init_file_srcFileSpec("") {
// Provide defaults for abits or size if one (but not the other) is specified.
if (this->abits == 0 && this->size != 0) {
this->abits = ceil_log2(this->size);
} else if (this->abits != 0 && this->size == 0) {
this->size = 1 << this->abits;
}
// Sanity-check this construction.
if (this->name == "") {
log_error("Nameless memory%s\n", this->atLine());
}
if (this->abits == 0 && this->size == 0) {
log_error("Memory %s has zero address bits and size%s\n", this->name.c_str(), this->atLine());
}
if (this->width == 0) {
log_error("Memory %s has zero width%s\n", this->name.c_str(), this->atLine());
}
}
// We need a default constructor for the dict insert.
memory() : pCell(0), read_latency(0), write_latency(1), init_file(""), init_file_srcFileSpec(""){}
const char *atLine() {
if (srcLine == "") {
if (pCell) {
auto p = pCell->attributes.find("\\src");
srcLine = " at " + p->second.decode_string();
}
}
return srcLine.c_str();
}
void add_memory_read_port(read_port &rp) {
read_ports.push_back(rp);
}
void add_memory_write_port(write_port &wp) {
write_ports.push_back(wp);
}
void add_memory_file(std::string init_file, std::string init_file_srcFileSpec) {
this->init_file = init_file;
this->init_file_srcFileSpec = init_file_srcFileSpec;
}
};
dict<string, memory> memories;
void register_memory(memory &m)
{
memories[m.name] = m;
}
void register_reverse_wire_map(string id, SigSpec sig)
{
for (int i = 0; i < GetSize(sig); i++)
reverse_wire_map[sig[i]] = make_pair(id, i);
}
FirrtlWorker(Module *module, std::ostream &f, RTLIL::Design *theDesign) : module(module), f(f), design(theDesign), indent(" ")
{
}
static string make_expr(const SigSpec &sig)
{
string expr;
for (auto chunk : sig.chunks())
{
string new_expr;
if (chunk.wire == nullptr)
{
std::vector<RTLIL::State> bits = chunk.data;
new_expr = stringf("UInt<%d>(\"h", GetSize(bits));
while (GetSize(bits) % 4 != 0)
bits.push_back(State::S0);
for (int i = GetSize(bits)-4; i >= 0; i -= 4)
{
int val = 0;
if (bits[i+0] == State::S1) val += 1;
if (bits[i+1] == State::S1) val += 2;
if (bits[i+2] == State::S1) val += 4;
if (bits[i+3] == State::S1) val += 8;
new_expr.push_back(val < 10 ? '0' + val : 'a' + val - 10);
}
new_expr += "\")";
}
else if (chunk.offset == 0 && chunk.width == chunk.wire->width)
{
new_expr = make_id(chunk.wire->name);
}
else
{
string wire_id = make_id(chunk.wire->name);
new_expr = stringf("bits(%s, %d, %d)", wire_id.c_str(), chunk.offset + chunk.width - 1, chunk.offset);
}
if (expr.empty())
expr = new_expr;
else
expr = "cat(" + new_expr + ", " + expr + ")";
}
return expr;
}
std::string fid(RTLIL::IdString internal_id)
{
return make_id(internal_id);
}
std::string cellname(RTLIL::Cell *cell)
{
return fid(cell->name).c_str();
}
void process_instance(RTLIL::Cell *cell, vector<string> &wire_exprs)
{
std::string cell_type = fid(cell->type);
std::string instanceOf;
// If this is a parameterized module, its parent module is encoded in the cell type
if (cell->type.begins_with("$paramod"))
{
std::string::iterator it;
for (it = cell_type.begin(); it < cell_type.end(); it++)
{
switch (*it) {
case '\\': /* FALL_THROUGH */
case '=': /* FALL_THROUGH */
case '\'': /* FALL_THROUGH */
case '$': instanceOf.append("_"); break;
default: instanceOf.append(1, *it); break;
}
}
}
else
{
instanceOf = cell_type;
}
std::string cell_name = cellname(cell);
std::string cell_name_comment;
if (cell_name != fid(cell->name))
cell_name_comment = " /* " + fid(cell->name) + " */ ";
else
cell_name_comment = "";
// Find the module corresponding to this instance.
auto instModule = design->module(cell->type);
// If there is no instance for this, just return.
if (instModule == NULL)
{
log_warning("No instance for %s.%s\n", cell_type.c_str(), cell_name.c_str());
return;
}
auto cellFileinfo = getFileinfo(cell->attributes);
wire_exprs.push_back(stringf("%s" "inst %s%s of %s %s", indent.c_str(), cell_name.c_str(), cell_name_comment.c_str(), instanceOf.c_str(), cellFileinfo.c_str()));
for (auto it = cell->connections().begin(); it != cell->connections().end(); ++it) {
if (it->second.size() > 0) {
const SigSpec &secondSig = it->second;
const std::string firstName = cell_name + "." + make_id(it->first);
const std::string secondExpr = make_expr(secondSig);
// Find the direction for this port.
FDirection dir = getPortFDirection(it->first, instModule);
std::string sourceExpr, sinkExpr;
const SigSpec *sinkSig = nullptr;
switch (dir) {
case FD_INOUT:
log_warning("Instance port connection %s.%s is INOUT; treating as OUT\n", cell_type.c_str(), log_signal(it->second));
/* FALLTHRU */
case FD_OUT:
sourceExpr = firstName;
sinkExpr = secondExpr;
sinkSig = &secondSig;
break;
case FD_NODIRECTION:
log_warning("Instance port connection %s.%s is NODIRECTION; treating as IN\n", cell_type.c_str(), log_signal(it->second));
/* FALLTHRU */
case FD_IN:
sourceExpr = secondExpr;
sinkExpr = firstName;
break;
default:
log_error("Instance port %s.%s unrecognized connection direction 0x%x !\n", cell_type.c_str(), log_signal(it->second), dir);
break;
}
// Check for subfield assignment.
std::string bitsString = "bits(";
if (sinkExpr.compare(0, bitsString.length(), bitsString) == 0) {
if (sinkSig == nullptr)
log_error("Unknown subfield %s.%s\n", cell_type.c_str(), sinkExpr.c_str());
// Don't generate the assignment here.
// Add the source and sink to the "reverse_wire_map" and we'll output the assignment
// as part of the coalesced subfield assignments for this wire.
register_reverse_wire_map(sourceExpr, *sinkSig);
} else {
wire_exprs.push_back(stringf("\n%s%s <= %s %s", indent.c_str(), sinkExpr.c_str(), sourceExpr.c_str(), cellFileinfo.c_str()));
}
}
}
wire_exprs.push_back(stringf("\n"));
}
// Given an expression for a shift amount, and a maximum width,
// generate the FIRRTL expression for equivalent dynamic shift taking into account FIRRTL shift semantics.
std::string gen_dshl(const string b_expr, const int b_width)
{
string result = b_expr;
if (b_width >= FIRRTL_MAX_DSH_WIDTH_ERROR) {
int max_shift_width_bits = FIRRTL_MAX_DSH_WIDTH_ERROR - 1;
string max_shift_string = stringf("UInt<%d>(%d)", max_shift_width_bits, (1<<max_shift_width_bits) - 1);
// Deal with the difference in semantics between FIRRTL and verilog
result = stringf("mux(gt(%s, %s), %s, bits(%s, %d, 0))", b_expr.c_str(), max_shift_string.c_str(), max_shift_string.c_str(), b_expr.c_str(), max_shift_width_bits - 1);
}
return result;
}
void run()
{
auto moduleFileinfo = getFileinfo(module->attributes);
f << stringf(" module %s: %s\n", make_id(module->name), moduleFileinfo.c_str());
vector<string> port_decls, wire_decls, cell_exprs, wire_exprs;
for (auto wire : module->wires())
{
const auto wireName = make_id(wire->name);
auto wireFileinfo = getFileinfo(wire->attributes);
// If a wire has initial data, issue a warning since FIRRTL doesn't currently support it.
if (wire->attributes.count("\\init")) {
log_warning("Initial value (%s) for (%s.%s) not supported\n",
wire->attributes.at("\\init").as_string().c_str(),
log_id(module), log_id(wire));
}
if (wire->port_id)
{
if (wire->port_input && wire->port_output)
log_error("Module port %s.%s is inout!\n", log_id(module), log_id(wire));
port_decls.push_back(stringf(" %s %s: UInt<%d> %s\n", wire->port_input ? "input" : "output",
wireName, wire->width, wireFileinfo.c_str()));
}
else
{
wire_decls.push_back(stringf(" wire %s: UInt<%d> %s\n", wireName, wire->width, wireFileinfo.c_str()));
}
}
for (auto cell : module->cells())
{
static Const ndef(0, 0);
// Is this cell is a module instance?
if (cell->type[0] != '$')
{
process_instance(cell, wire_exprs);
continue;
}
// Not a module instance. Set up cell properties
bool extract_y_bits = false; // Assume no extraction of final bits will be required.
int a_width = cell->parameters.at("\\A_WIDTH", ndef).as_int(); // The width of "A"
int b_width = cell->parameters.at("\\B_WIDTH", ndef).as_int(); // The width of "A"
const int y_width = cell->parameters.at("\\Y_WIDTH", ndef).as_int(); // The width of the result
const bool a_signed = cell->parameters.at("\\A_SIGNED", ndef).as_bool();
const bool b_signed = cell->parameters.at("\\B_SIGNED", ndef).as_bool();
bool firrtl_is_signed = a_signed; // The result is signed (subsequent code may change this).
int firrtl_width = 0;
string primop;
bool always_uint = false;
string y_id = make_id(cell->name);
if (cell->type.in("$not", "$logic_not", "$neg", "$reduce_and", "$reduce_or", "$reduce_xor", "$reduce_bool", "$reduce_xnor"))
{
string a_expr = make_expr(cell->getPort("\\A"));
wire_decls.push_back(stringf(" wire %s: UInt<%d>\n", y_id.c_str(), y_width));
if (a_signed) {
a_expr = "asSInt(" + a_expr + ")";
}
// Don't use the results of logical operations (a single bit) to control padding
if (!(cell->type.in("$eq", "$eqx", "$gt", "$ge", "$lt", "$le", "$ne", "$nex", "$reduce_bool", "$logic_not") && y_width == 1) ) {
a_expr = stringf("pad(%s, %d)", a_expr.c_str(), y_width);
}
// Assume the FIRRTL width is a single bit.
firrtl_width = 1;
if (cell->type == "$not") primop = "not";
else if (cell->type == "$neg") {
primop = "neg";
firrtl_is_signed = true; // Result of "neg" is signed (an SInt).
firrtl_width = a_width;
} else if (cell->type == "$logic_not") {
primop = "eq";
a_expr = stringf("%s, UInt(0)", a_expr.c_str());
}
else if (cell->type == "$reduce_and") primop = "andr";
else if (cell->type == "$reduce_or") primop = "orr";
else if (cell->type == "$reduce_xor") primop = "xorr";
else if (cell->type == "$reduce_xnor") {
primop = "not";
a_expr = stringf("xorr(%s)", a_expr.c_str());
}
else if (cell->type == "$reduce_bool") {
primop = "neq";
// Use the sign of the a_expr and its width as the type (UInt/SInt) and width of the comparand.
a_expr = stringf("%s, %cInt<%d>(0)", a_expr.c_str(), a_signed ? 'S' : 'U', a_width);
}
string expr = stringf("%s(%s)", primop.c_str(), a_expr.c_str());
if ((firrtl_is_signed && !always_uint))
expr = stringf("asUInt(%s)", expr.c_str());
cell_exprs.push_back(stringf(" %s <= %s\n", y_id.c_str(), expr.c_str()));
register_reverse_wire_map(y_id, cell->getPort("\\Y"));
continue;
}
if (cell->type.in("$add", "$sub", "$mul", "$div", "$mod", "$xor", "$xnor", "$and", "$or", "$eq", "$eqx",
"$gt", "$ge", "$lt", "$le", "$ne", "$nex", "$shr", "$sshr", "$sshl", "$shl",
"$logic_and", "$logic_or", "$pow"))
{
string a_expr = make_expr(cell->getPort("\\A"));
string b_expr = make_expr(cell->getPort("\\B"));
wire_decls.push_back(stringf(" wire %s: UInt<%d>\n", y_id.c_str(), y_width));
if (a_signed) {
a_expr = "asSInt(" + a_expr + ")";
// Expand the "A" operand to the result width
if (a_width < y_width) {
a_expr = stringf("pad(%s, %d)", a_expr.c_str(), y_width);
a_width = y_width;
}
}
// Shift amount is always unsigned, and needn't be padded to result width,
// otherwise, we need to cast the b_expr appropriately
if (b_signed && !cell->type.in("$shr", "$sshr", "$shl", "$sshl", "$pow")) {
b_expr = "asSInt(" + b_expr + ")";
// Expand the "B" operand to the result width
if (b_width < y_width) {
b_expr = stringf("pad(%s, %d)", b_expr.c_str(), y_width);
b_width = y_width;
}
}
// For the arithmetic ops, expand operand widths to result widths befor performing the operation.
// This corresponds (according to iverilog) to what verilog compilers implement.
if (cell->type.in("$add", "$sub", "$mul", "$div", "$mod", "$xor", "$xnor", "$and", "$or"))
{
if (a_width < y_width) {
a_expr = stringf("pad(%s, %d)", a_expr.c_str(), y_width);
a_width = y_width;
}
if (b_width < y_width) {
b_expr = stringf("pad(%s, %d)", b_expr.c_str(), y_width);
b_width = y_width;
}
}
// Assume the FIRRTL width is the width of "A"
firrtl_width = a_width;
auto a_sig = cell->getPort("\\A");
if (cell->type == "$add") {
primop = "add";
firrtl_is_signed = a_signed | b_signed;
firrtl_width = max(a_width, b_width);
} else if (cell->type == "$sub") {
primop = "sub";
firrtl_is_signed = true;
int a_widthInc = (!a_signed && b_signed) ? 2 : (a_signed && !b_signed) ? 1 : 0;
int b_widthInc = (a_signed && !b_signed) ? 2 : (!a_signed && b_signed) ? 1 : 0;
firrtl_width = max(a_width + a_widthInc, b_width + b_widthInc);
} else if (cell->type == "$mul") {
primop = "mul";
firrtl_is_signed = a_signed | b_signed;
firrtl_width = a_width + b_width;
} else if (cell->type == "$div") {
primop = "div";
firrtl_is_signed = a_signed | b_signed;
firrtl_width = a_width;
} else if (cell->type == "$mod") {
primop = "rem";
firrtl_width = min(a_width, b_width);
} else if (cell->type == "$and") {
primop = "and";
always_uint = true;
firrtl_width = max(a_width, b_width);
}
else if (cell->type == "$or" ) {
primop = "or";
always_uint = true;
firrtl_width = max(a_width, b_width);
}
else if (cell->type == "$xor") {
primop = "xor";
always_uint = true;
firrtl_width = max(a_width, b_width);
}
else if (cell->type == "$xnor") {
primop = "xnor";
always_uint = true;
firrtl_width = max(a_width, b_width);
}
else if ((cell->type == "$eq") | (cell->type == "$eqx")) {
primop = "eq";
always_uint = true;
firrtl_width = 1;
}
else if ((cell->type == "$ne") | (cell->type == "$nex")) {
primop = "neq";
always_uint = true;
firrtl_width = 1;
}
else if (cell->type == "$gt") {
primop = "gt";
always_uint = true;
firrtl_width = 1;
}
else if (cell->type == "$ge") {
primop = "geq";
always_uint = true;
firrtl_width = 1;
}
else if (cell->type == "$lt") {
primop = "lt";
always_uint = true;
firrtl_width = 1;
}
else if (cell->type == "$le") {
primop = "leq";
always_uint = true;
firrtl_width = 1;
}
else if ((cell->type == "$shl") | (cell->type == "$sshl")) {
// FIRRTL will widen the result (y) by the amount of the shift.
// We'll need to offset this by extracting the un-widened portion as Verilog would do.
extract_y_bits = true;
// Is the shift amount constant?
auto b_sig = cell->getPort("\\B");
if (b_sig.is_fully_const()) {
primop = "shl";
int shift_amount = b_sig.as_int();
b_expr = std::to_string(shift_amount);
firrtl_width = a_width + shift_amount;
} else {
primop = "dshl";
// Convert from FIRRTL left shift semantics.
b_expr = gen_dshl(b_expr, b_width);
firrtl_width = a_width + (1 << b_width) - 1;
}
}
else if ((cell->type == "$shr") | (cell->type == "$sshr")) {
// We don't need to extract a specific range of bits.
extract_y_bits = false;
// Is the shift amount constant?
auto b_sig = cell->getPort("\\B");
if (b_sig.is_fully_const()) {
primop = "shr";
int shift_amount = b_sig.as_int();
b_expr = std::to_string(shift_amount);
firrtl_width = max(1, a_width - shift_amount);
} else {
primop = "dshr";
firrtl_width = a_width;
}
// We'll need to do some special fixups if the source (and thus result) is signed.
if (firrtl_is_signed) {
// If this is a "logical" shift right, pretend the source is unsigned.
if (cell->type == "$shr") {
a_expr = "asUInt(" + a_expr + ")";
}
}
}
else if ((cell->type == "$logic_and")) {
primop = "and";
a_expr = "neq(" + a_expr + ", UInt(0))";
b_expr = "neq(" + b_expr + ", UInt(0))";
always_uint = true;
firrtl_width = 1;
}
else if ((cell->type == "$logic_or")) {
primop = "or";
a_expr = "neq(" + a_expr + ", UInt(0))";
b_expr = "neq(" + b_expr + ", UInt(0))";
always_uint = true;
firrtl_width = 1;
}
else if ((cell->type == "$pow")) {
if (a_sig.is_fully_const() && a_sig.as_int() == 2) {
// We'll convert this to a shift. To simplify things, change the a_expr to "1"
// so we can use b_expr directly as a shift amount.
// Only support 2 ** N (i.e., shift left)
// FIRRTL will widen the result (y) by the amount of the shift.
// We'll need to offset this by extracting the un-widened portion as Verilog would do.
a_expr = firrtl_is_signed ? "SInt(1)" : "UInt(1)";
extract_y_bits = true;
// Is the shift amount constant?
auto b_sig = cell->getPort("\\B");
if (b_sig.is_fully_const()) {
primop = "shl";
int shiftAmount = b_sig.as_int();
if (shiftAmount < 0) {
log_error("Negative power exponent - %d: %s.%s\n", shiftAmount, log_id(module), log_id(cell));
}
b_expr = std::to_string(shiftAmount);
firrtl_width = a_width + shiftAmount;
} else {
primop = "dshl";
// Convert from FIRRTL left shift semantics.
b_expr = gen_dshl(b_expr, b_width);
firrtl_width = a_width + (1 << b_width) - 1;
}
} else {
log_error("Non power 2: %s.%s\n", log_id(module), log_id(cell));
}
}
if (!cell->parameters.at("\\B_SIGNED").as_bool()) {
b_expr = "asUInt(" + b_expr + ")";
}
string expr;
// Deal with $xnor == ~^ (not xor)
if (primop == "xnor") {
expr = stringf("not(xor(%s, %s))", a_expr.c_str(), b_expr.c_str());
} else {
expr = stringf("%s(%s, %s)", primop.c_str(), a_expr.c_str(), b_expr.c_str());
}
// Deal with FIRRTL's "shift widens" semantics, or the need to widen the FIRRTL result.
// If the operation is signed, the FIRRTL width will be 1 one bit larger.
if (extract_y_bits) {
expr = stringf("bits(%s, %d, 0)", expr.c_str(), y_width - 1);
} else if (firrtl_is_signed && (firrtl_width + 1) < y_width) {
expr = stringf("pad(%s, %d)", expr.c_str(), y_width);
}
if ((firrtl_is_signed && !always_uint))
expr = stringf("asUInt(%s)", expr.c_str());
cell_exprs.push_back(stringf(" %s <= %s\n", y_id.c_str(), expr.c_str()));
register_reverse_wire_map(y_id, cell->getPort("\\Y"));
continue;
}
if (cell->type.in("$mux"))
{
int width = cell->parameters.at("\\WIDTH").as_int();
string a_expr = make_expr(cell->getPort("\\A"));
string b_expr = make_expr(cell->getPort("\\B"));
string s_expr = make_expr(cell->getPort("\\S"));
wire_decls.push_back(stringf(" wire %s: UInt<%d>\n", y_id.c_str(), width));
string expr = stringf("mux(%s, %s, %s)", s_expr.c_str(), b_expr.c_str(), a_expr.c_str());
cell_exprs.push_back(stringf(" %s <= %s\n", y_id.c_str(), expr.c_str()));
register_reverse_wire_map(y_id, cell->getPort("\\Y"));
continue;
}
if (cell->type.in("$mem"))
{
string mem_id = make_id(cell->name);
int abits = cell->parameters.at("\\ABITS").as_int();
int width = cell->parameters.at("\\WIDTH").as_int();
int size = cell->parameters.at("\\SIZE").as_int();
memory m(cell, mem_id, abits, size, width);
int rd_ports = cell->parameters.at("\\RD_PORTS").as_int();
int wr_ports = cell->parameters.at("\\WR_PORTS").as_int();
Const initdata = cell->parameters.at("\\INIT");
for (State bit : initdata.bits)
if (bit != State::Sx)
log_error("Memory with initialization data: %s.%s\n", log_id(module), log_id(cell));
Const rd_clk_enable = cell->parameters.at("\\RD_CLK_ENABLE");
Const wr_clk_enable = cell->parameters.at("\\WR_CLK_ENABLE");
Const wr_clk_polarity = cell->parameters.at("\\WR_CLK_POLARITY");
int offset = cell->parameters.at("\\OFFSET").as_int();
if (offset != 0)
log_error("Memory with nonzero offset: %s.%s\n", log_id(module), log_id(cell));
for (int i = 0; i < rd_ports; i++)
{
if (rd_clk_enable[i] != State::S0)
log_error("Clocked read port %d on memory %s.%s.\n", i, log_id(module), log_id(cell));
SigSpec addr_sig = cell->getPort("\\RD_ADDR").extract(i*abits, abits);
SigSpec data_sig = cell->getPort("\\RD_DATA").extract(i*width, width);
string addr_expr = make_expr(addr_sig);
string name(stringf("%s.r%d", m.name.c_str(), i));
bool clk_enable = false;
bool clk_parity = true;
bool transparency = false;
SigSpec ena_sig = RTLIL::SigSpec(RTLIL::State::S1, 1);
SigSpec clk_sig = RTLIL::SigSpec(RTLIL::State::S0, 1);
read_port rp(name, clk_enable, clk_parity, transparency, clk_sig, ena_sig, addr_sig);
m.add_memory_read_port(rp);
cell_exprs.push_back(rp.gen_read(indent.c_str()));
register_reverse_wire_map(stringf("%s.data", name.c_str()), data_sig);
}
for (int i = 0; i < wr_ports; i++)
{
if (wr_clk_enable[i] != State::S1)
log_error("Unclocked write port %d on memory %s.%s.\n", i, log_id(module), log_id(cell));
if (wr_clk_polarity[i] != State::S1)
log_error("Negedge write port %d on memory %s.%s.\n", i, log_id(module), log_id(cell));
string name(stringf("%s.w%d", m.name.c_str(), i));
bool clk_enable = true;
bool clk_parity = true;
bool transparency = false;
SigSpec addr_sig =cell->getPort("\\WR_ADDR").extract(i*abits, abits);
string addr_expr = make_expr(addr_sig);
SigSpec data_sig =cell->getPort("\\WR_DATA").extract(i*width, width);
string data_expr = make_expr(data_sig);
SigSpec clk_sig = cell->getPort("\\WR_CLK").extract(i);
string clk_expr = make_expr(clk_sig);
SigSpec wen_sig = cell->getPort("\\WR_EN").extract(i*width, width);
string wen_expr = make_expr(wen_sig[0]);
for (int i = 1; i < GetSize(wen_sig); i++)
if (wen_sig[0] != wen_sig[i])
log_error("Complex write enable on port %d on memory %s.%s.\n", i, log_id(module), log_id(cell));
SigSpec mask_sig = RTLIL::SigSpec(RTLIL::State::S1, 1);
write_port wp(name, clk_enable, clk_parity, transparency, clk_sig, wen_sig[0], addr_sig, mask_sig);
m.add_memory_write_port(wp);
cell_exprs.push_back(stringf("%s%s.data <= %s\n", indent.c_str(), name.c_str(), data_expr.c_str()));
cell_exprs.push_back(wp.gen_write(indent.c_str()));
}
register_memory(m);
continue;
}
if (cell->type.in("$memwr", "$memrd", "$meminit"))
{
std::string cell_type = fid(cell->type);
std::string mem_id = make_id(cell->parameters["\\MEMID"].decode_string());
int abits = cell->parameters.at("\\ABITS").as_int();
int width = cell->parameters.at("\\WIDTH").as_int();
memory *mp = nullptr;
if (cell->type == "$meminit" ) {
log_error("$meminit (%s.%s.%s) currently unsupported\n", log_id(module), log_id(cell), mem_id.c_str());
} else {
// It's a $memwr or $memrd. Remember the read/write port parameters for the eventual FIRRTL memory definition.
auto addrSig = cell->getPort("\\ADDR");
auto dataSig = cell->getPort("\\DATA");
auto enableSig = cell->getPort("\\EN");
auto clockSig = cell->getPort("\\CLK");
Const clk_enable = cell->parameters.at("\\CLK_ENABLE");
Const clk_polarity = cell->parameters.at("\\CLK_POLARITY");
// Do we already have an entry for this memory?
if (memories.count(mem_id) == 0) {
memory m(cell, mem_id, abits, 0, width);
register_memory(m);
}
mp = &memories.at(mem_id);
int portNum = 0;
bool transparency = false;
string data_expr = make_expr(dataSig);
if (cell->type.in("$memwr")) {
portNum = (int) mp->write_ports.size();
write_port wp(stringf("%s.w%d", mem_id.c_str(), portNum), clk_enable.as_bool(), clk_polarity.as_bool(), transparency, clockSig, enableSig, addrSig, dataSig);
mp->add_memory_write_port(wp);
cell_exprs.push_back(stringf("%s%s.data <= %s\n", indent.c_str(), wp.name.c_str(), data_expr.c_str()));
cell_exprs.push_back(wp.gen_write(indent.c_str()));
} else if (cell->type.in("$memrd")) {
portNum = (int) mp->read_ports.size();
read_port rp(stringf("%s.r%d", mem_id.c_str(), portNum), clk_enable.as_bool(), clk_polarity.as_bool(), transparency, clockSig, enableSig, addrSig);
mp->add_memory_read_port(rp);
cell_exprs.push_back(rp.gen_read(indent.c_str()));
register_reverse_wire_map(stringf("%s.data", rp.name.c_str()), dataSig);
}
}
continue;
}
if (cell->type.in("$dff"))
{
bool clkpol = cell->parameters.at("\\CLK_POLARITY").as_bool();
if (clkpol == false)
log_error("Negative edge clock on FF %s.%s.\n", log_id(module), log_id(cell));
int width = cell->parameters.at("\\WIDTH").as_int();
string expr = make_expr(cell->getPort("\\D"));
string clk_expr = "asClock(" + make_expr(cell->getPort("\\CLK")) + ")";
wire_decls.push_back(stringf(" reg %s: UInt<%d>, %s\n", y_id.c_str(), width, clk_expr.c_str()));
cell_exprs.push_back(stringf(" %s <= %s\n", y_id.c_str(), expr.c_str()));
register_reverse_wire_map(y_id, cell->getPort("\\Q"));
continue;
}
// This may be a parameterized module - paramod.
if (cell->type.begins_with("$paramod"))
{
process_instance(cell, wire_exprs);
continue;
}
if (cell->type == "$shiftx") {
// assign y = a[b +: y_width];
// We'll extract the correct bits as part of the primop.
string a_expr = make_expr(cell->getPort("\\A"));
// Get the initial bit selector
string b_expr = make_expr(cell->getPort("\\B"));
wire_decls.push_back(stringf(" wire %s: UInt<%d>\n", y_id.c_str(), y_width));
if (cell->getParam("\\B_SIGNED").as_bool()) {
// Use validif to constrain the selection (test the sign bit)
auto b_string = b_expr.c_str();
int b_sign = cell->parameters.at("\\B_WIDTH").as_int() - 1;
b_expr = stringf("validif(not(bits(%s, %d, %d)), %s)", b_string, b_sign, b_sign, b_string);
}
string expr = stringf("dshr(%s, %s)", a_expr.c_str(), b_expr.c_str());
cell_exprs.push_back(stringf(" %s <= %s\n", y_id.c_str(), expr.c_str()));
register_reverse_wire_map(y_id, cell->getPort("\\Y"));
continue;
}
if (cell->type == "$shift") {
// assign y = a >> b;
// where b may be negative
string a_expr = make_expr(cell->getPort("\\A"));
string b_expr = make_expr(cell->getPort("\\B"));
auto b_string = b_expr.c_str();
string expr;
wire_decls.push_back(stringf(" wire %s: UInt<%d>\n", y_id.c_str(), y_width));
if (cell->getParam("\\B_SIGNED").as_bool()) {
// We generate a left or right shift based on the sign of b.
std::string dshl = stringf("bits(dshl(%s, %s), 0, %d)", a_expr.c_str(), gen_dshl(b_expr, b_width).c_str(), y_width);
std::string dshr = stringf("dshr(%s, %s)", a_expr.c_str(), b_string);
expr = stringf("mux(%s < 0, %s, %s)",
b_string,
dshl.c_str(),
dshr.c_str()
);
} else {
expr = stringf("dshr(%s, %s)", a_expr.c_str(), b_string);
}
cell_exprs.push_back(stringf(" %s <= %s\n", y_id.c_str(), expr.c_str()));
register_reverse_wire_map(y_id, cell->getPort("\\Y"));
continue;
}
if (cell->type == "$pos") {
// assign y = a;
// printCell(cell);
string a_expr = make_expr(cell->getPort("\\A"));
// Verilog appears to treat the result as signed, so if the result is wider than "A",
// we need to pad.
if (a_width < y_width) {
a_expr = stringf("pad(%s, %d)", a_expr.c_str(), y_width);
}
wire_decls.push_back(stringf(" wire %s: UInt<%d>\n", y_id.c_str(), y_width));
cell_exprs.push_back(stringf(" %s <= %s\n", y_id.c_str(), a_expr.c_str()));
register_reverse_wire_map(y_id, cell->getPort("\\Y"));
continue;
}
log_error("Cell type not supported: %s (%s.%s)\n", log_id(cell->type), log_id(module), log_id(cell));
}
for (auto conn : module->connections())
{
string y_id = next_id();
int y_width = GetSize(conn.first);
string expr = make_expr(conn.second);
wire_decls.push_back(stringf(" wire %s: UInt<%d>\n", y_id.c_str(), y_width));
cell_exprs.push_back(stringf(" %s <= %s\n", y_id.c_str(), expr.c_str()));
register_reverse_wire_map(y_id, conn.first);
}
for (auto wire : module->wires())
{
string expr;
if (wire->port_input)
continue;
int cursor = 0;
bool is_valid = false;
bool make_unconn_id = false;
while (cursor < wire->width)
{
int chunk_width = 1;
string new_expr;
SigBit start_bit(wire, cursor);
if (reverse_wire_map.count(start_bit))
{
pair<string, int> start_map = reverse_wire_map.at(start_bit);
while (cursor+chunk_width < wire->width)
{
SigBit stop_bit(wire, cursor+chunk_width);
if (reverse_wire_map.count(stop_bit) == 0)
break;
pair<string, int> stop_map = reverse_wire_map.at(stop_bit);
stop_map.second -= chunk_width;
if (start_map != stop_map)
break;
chunk_width++;
}
new_expr = stringf("bits(%s, %d, %d)", start_map.first.c_str(),
start_map.second + chunk_width - 1, start_map.second);
is_valid = true;
}
else
{
if (unconn_id.empty()) {
unconn_id = next_id();
make_unconn_id = true;
}
new_expr = unconn_id;
}
if (expr.empty())
expr = new_expr;
else
expr = "cat(" + new_expr + ", " + expr + ")";
cursor += chunk_width;
}
if (is_valid) {
if (make_unconn_id) {
wire_decls.push_back(stringf(" wire %s: UInt<1>\n", unconn_id.c_str()));
wire_decls.push_back(stringf(" %s is invalid\n", unconn_id.c_str()));
}
wire_exprs.push_back(stringf(" %s <= %s\n", make_id(wire->name), expr.c_str()));
} else {
if (make_unconn_id) {
unconn_id.clear();
}
wire_decls.push_back(stringf(" %s is invalid\n", make_id(wire->name)));
}
}
for (auto str : port_decls)
f << str;
f << stringf("\n");
for (auto str : wire_decls)
f << str;
f << stringf("\n");
// If we have any memory definitions, output them.
for (auto kv : memories) {
memory &m = kv.second;
f << stringf(" mem %s:\n", m.name.c_str());
f << stringf(" data-type => UInt<%d>\n", m.width);
f << stringf(" depth => %d\n", m.size);
for (int i = 0; i < (int) m.read_ports.size(); i += 1) {
f << stringf(" reader => r%d\n", i);
}
for (int i = 0; i < (int) m.write_ports.size(); i += 1) {
f << stringf(" writer => w%d\n", i);
}
f << stringf(" read-latency => %d\n", m.read_latency);
f << stringf(" write-latency => %d\n", m.write_latency);
f << stringf(" read-under-write => undefined\n");
}
f << stringf("\n");
for (auto str : cell_exprs)
f << str;
f << stringf("\n");
for (auto str : wire_exprs)
f << str;
}
};
struct FirrtlBackend : public Backend {
FirrtlBackend() : Backend("firrtl", "write design to a FIRRTL file") { }
void help() YS_OVERRIDE
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" write_firrtl [options] [filename]\n");
log("\n");
log("Write a FIRRTL netlist of the current design.\n");
log("The following commands are executed by this command:\n");
log(" pmuxtree\n");
log("\n");
}
void execute(std::ostream *&f, std::string filename, std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
{
size_t argidx = args.size(); // We aren't expecting any arguments.
// If we weren't explicitly passed a filename, use the last argument (if it isn't a flag).
if (filename == "") {
if (argidx > 0 && args[argidx - 1][0] != '-') {
// extra_args and friends need to see this argument.
argidx -= 1;
filename = args[argidx];
}
}
extra_args(f, filename, args, argidx);
if (!design->full_selection())
log_cmd_error("This command only operates on fully selected designs!\n");
log_header(design, "Executing FIRRTL backend.\n");
log_push();
Pass::call(design, stringf("pmuxtree"));
namecache.clear();
autoid_counter = 0;
// Get the top module, or a reasonable facsimile - we need something for the circuit name.
Module *top = design->top_module();
Module *last = nullptr;
// Generate module and wire names.
for (auto module : design->modules()) {
make_id(module->name);
last = module;
if (top == nullptr && module->get_bool_attribute("\\top")) {
top = module;
}
for (auto wire : module->wires())
if (wire->port_id)
make_id(wire->name);
}
if (top == nullptr)
top = last;
auto circuitFileinfo = getFileinfo(top->attributes);
*f << stringf("circuit %s: %s\n", make_id(top->name), circuitFileinfo.c_str());
for (auto module : design->modules())
{
FirrtlWorker worker(module, *f, design);
worker.run();
}
namecache.clear();
autoid_counter = 0;
}
} FirrtlBackend;
PRIVATE_NAMESPACE_END
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