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yosys/backends/firrtl/firrtl.cc

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/*
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2012 Claire Xenia Wolf <claire@yosyshq.com>
*
* 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/log.h"
#include "kernel/mem.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
std::string getFileinfo(const RTLIL::AttrObject *design_entity)
{
std::string src(design_entity->get_src_attribute());
std::string fileinfo_str = src.empty() ? "" : "@[" + src + "]";
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();
}
std::string dump_const_string(const RTLIL::Const &data)
{
std::string res_str;
std::string str = data.decode_string();
for (size_t i = 0; i < str.size(); i++)
{
if (str[i] == '\n')
res_str += "\\n";
else if (str[i] == '\t')
res_str += "\\t";
else if (str[i] < 32)
res_str += stringf("\\%03o", str[i]);
else if (str[i] == '"')
res_str += "\\\"";
else if (str[i] == '\\')
res_str += "\\\\";
else
res_str += str[i];
}
return res_str;
}
std::string dump_const(const RTLIL::Const &data)
{
std::string res_str;
// // For debugging purposes to find out how Yosys encodes flags.
// res_str += stringf("flags_%x --> ", data.flags);
// Real-valued parameter.
if (data.flags & RTLIL::CONST_FLAG_REAL)
{
// Yosys stores real values as strings, so we call the string dumping code.
res_str += dump_const_string(data);
}
// String parameter.
else if (data.flags & RTLIL::CONST_FLAG_STRING)
{
res_str += "\"";
res_str += dump_const_string(data);
res_str += "\"";
}
// Numeric (non-real) parameter.
else
{
int width = data.bits.size();
// If a standard 32-bit int, then emit standard int value like "56" or
// "-56". Firrtl supports negative-valued int literals.
//
// SignedInt
// : ( '+' | '-' ) PosInt
// ;
if (width <= 32)
{
int32_t int_val = 0;
for (int i = 0; i < width; i++)
{
switch (data.bits[i])
{
case State::S0: break;
case State::S1: int_val |= (1 << i); break;
default:
log_error("Unexpected int value\n");
break;
}
}
res_str += stringf("%d", int_val);
}
else
{
// If value is larger than 32 bits, then emit a binary representation of
// the number as integers are not large enough to contain the result.
// There is a caveat to this approach though:
//
// Note that parameter may be defined as having a fixed width as follows:
//
// parameter signed [26:0] test_signed;
// parameter [26:0] test_unsigned;
// parameter signed [40:0] test_signed_large;
//
// However, if you assign a value on the RHS without specifying the
// precision, then yosys considers the value you used as an int and
// assigns it a width of 32 bits regardless of the type of the parameter.
//
// defparam <inst_name> .test_signed = 49; (width = 32, though should be 27 based on definition)
// defparam <inst_name> .test_unsigned = 40'd35; (width = 40, though should be 27 based on definition)
// defparam <inst_name> .test_signed_large = 40'd12; (width = 40)
//
// We therefore may lose the precision of the original verilog literal if
// it was written without its bitwidth specifier.
// Emit binary prefix for string.
res_str += "\"b";
// Emit bits.
for (int i = width - 1; i >= 0; i--)
{
log_assert(i < width);
switch (data.bits[i])
{
case State::S0: res_str += "0"; break;
case State::S1: res_str += "1"; break;
case State::Sx: res_str += "x"; break;
case State::Sz: res_str += "z"; break;
case State::Sa: res_str += "-"; break;
case State::Sm: res_str += "m"; break;
}
}
res_str += "\"";
}
}
return res_str;
}
std::string extmodule_name(RTLIL::Cell *cell, RTLIL::Module *mod_instance)
{
// Since we are creating a custom extmodule for every cell that instantiates
// this blackbox, we need to create a custom name for it. We just use the
// name of the blackbox itself followed by the name of the cell.
const std::string cell_name = std::string(make_id(cell->name));
const std::string blackbox_name = std::string(make_id(mod_instance->name));
const std::string extmodule_name = blackbox_name + "_" + cell_name;
return extmodule_name;
}
/**
* Emits a parameterized extmodule. Instance parameters are obtained from
* ''cell'' as it represents the instantiation of the blackbox defined by
* ''mod_instance'' and therefore contains all its instance parameters.
*/
void emit_extmodule(RTLIL::Cell *cell, RTLIL::Module *mod_instance, std::ostream &f)
{
const std::string indent = " ";
const std::string blackbox_name = std::string(make_id(mod_instance->name));
const std::string exported_name = extmodule_name(cell, mod_instance);
// We use the cell's fileinfo for this extmodule as its parameters come from
// the cell and not from the module itself (the module contains default
// parameters, not the instance-specific ones we're using to emit the
// extmodule).
const std::string extmoduleFileinfo = getFileinfo(cell);
// Emit extmodule header.
f << stringf(" extmodule %s: %s\n", exported_name.c_str(), extmoduleFileinfo.c_str());
// Emit extmodule ports.
for (auto wire : mod_instance->wires())
{
const auto wireName = make_id(wire->name);
const std::string wireFileinfo = getFileinfo(wire);
if (wire->port_input && wire->port_output)
{
log_error("Module port %s.%s is inout!\n", log_id(mod_instance), log_id(wire));
}
const std::string portDecl = stringf("%s%s %s: UInt<%d> %s\n",
indent.c_str(),
wire->port_input ? "input" : "output",
wireName,
wire->width,
wireFileinfo.c_str()
);
f << portDecl;
}
// Emit extmodule "defname" field. This is the name of the verilog blackbox
// that is used when verilog is emitted, so we use the name of mod_instance
// here.
f << stringf("%sdefname = %s\n", indent.c_str(), blackbox_name.c_str());
// Emit extmodule generic parameters.
for (const auto &p : cell->parameters)
{
const RTLIL::IdString p_id = p.first;
const RTLIL::Const p_value = p.second;
std::string param_name(p_id.c_str());
const std::string param_value = dump_const(p_value);
// Remove backslashes from parameters as these come from the internal RTLIL
// naming scheme, but should not exist in the emitted firrtl blackboxes.
// When firrtl is converted to verilog and given to downstream synthesis
// tools, these tools expect to find blackbox names and parameters as they
// were originally defined, i.e. without the extra RTLIL naming conventions.
param_name.erase(
std::remove(param_name.begin(), param_name.end(), '\\'),
param_name.end()
);
f << stringf("%sparameter %s = %s\n", indent.c_str(), param_name.c_str(), param_value.c_str());
}
f << "\n";
}
/**
* Emits extmodules for every instantiated blackbox in the design.
*
* RTLIL stores instance parameters at the cell's instantiation location.
* However, firrtl does not support module parameterization (everything is
* already elaborated). Firrtl instead supports external modules (extmodule),
* i.e. blackboxes that are defined by verilog and which have no body in
* firrtl itself other than the declaration of the blackboxes ports and
* parameters.
*
* Furthermore, firrtl does not support parameterization (even of extmodules)
* at a module's instantiation location and users must instead declare
* different extmodules with different instance parameters in the extmodule
* definition itself.
*
* This function goes through the design to identify all RTLIL blackboxes
* and emit parameterized extmodules with a unique name for each of them. The
* name that's given to the extmodule is
*
* <blackbox_name>_<instance_name>
*
* Beware that it is therefore necessary for users to replace "parameterized"
* instances in the RTLIL sense with these custom extmodules for the firrtl to
* be valid.
*/
void emit_elaborated_extmodules(RTLIL::Design *design, std::ostream &f)
{
for (auto module : design->modules())
{
for (auto cell : module->cells())
{
// Is this cell a module instance?
bool cellIsModuleInstance = cell->type[0] != '$';
if (cellIsModuleInstance)
{
// Find the module corresponding to this instance.
auto modInstance = design->module(cell->type);
// Ensure that we actually have a module instance
if (modInstance == nullptr) {
log_error("Unknown cell type %s\n", cell->type.c_str());
return;
}
bool modIsBlackbox = modInstance->get_blackbox_attribute();
if (modIsBlackbox)
{
emit_extmodule(cell, modInstance, f);
}
}
}
}
}
struct FirrtlWorker
{
Module *module;
std::ostream &f;
dict<SigBit, pair<string, int>> reverse_wire_map;
string unconn_id;
RTLIL::Design *design;
std::string indent;
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"))
{
log_assert(cell->has_attribute(ID::hdlname));
instanceOf = cell->get_string_attribute(ID::hdlname);
}
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;
}
// If the instance is that of a blackbox, use the modified extmodule name
// that contains per-instance parameterizations. These instances were
// emitted earlier in the firrtl backend.
const std::string instanceName = instModule->get_blackbox_attribute() ?
extmodule_name(cell, instModule) :
instanceOf;
std::string cellFileinfo = getFileinfo(cell);
wire_exprs.push_back(stringf("%s" "inst %s%s of %s %s", indent.c_str(), cell_name.c_str(), cell_name_comment.c_str(), instanceName.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));
YS_FALLTHROUGH
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));
YS_FALLTHROUGH
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 emit_module()
{
std::string moduleFileinfo = getFileinfo(module);
f << stringf(" module %s: %s\n", make_id(module->name), moduleFileinfo.c_str());
vector<string> port_decls, wire_decls, mem_exprs, cell_exprs, wire_exprs;
std::vector<Mem> memories = Mem::get_all_memories(module);
for (auto &mem : memories)
mem.narrow();
for (auto wire : module->wires())
{
const auto wireName = make_id(wire->name);
std::string wireFileinfo = getFileinfo(wire);
// If a wire has initial data, issue a warning since FIRRTL doesn't currently support it.
if (wire->attributes.count(ID::init)) {
log_warning("Initial value (%s) for (%s.%s) not supported\n",
wire->attributes.at(ID::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 %s: UInt<%d> %s\n", indent.c_str(), wire->port_input ? "input" : "output",
wireName, wire->width, wireFileinfo.c_str()));
}
else
{
wire_decls.push_back(stringf("%swire %s: UInt<%d> %s\n", indent.c_str(), wireName, wire->width, wireFileinfo.c_str()));
}
}
for (auto cell : module->cells())
{
Const ndef(0, 0);
// Is this cell is a module instance?
if (module->design->module(cell->type))
{
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(ID::A_WIDTH, ndef).as_int(); // The width of "A"
int b_width = cell->parameters.at(ID::B_WIDTH, ndef).as_int(); // The width of "A"
const int y_width = cell->parameters.at(ID::Y_WIDTH, ndef).as_int(); // The width of the result
const bool a_signed = cell->parameters.at(ID::A_SIGNED, ndef).as_bool();
const bool b_signed = cell->parameters.at(ID::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);
std::string cellFileinfo = getFileinfo(cell);
if (cell->type.in(ID($not), ID($logic_not), ID($_NOT_), ID($neg), ID($reduce_and), ID($reduce_or), ID($reduce_xor), ID($reduce_bool), ID($reduce_xnor)))
{
string a_expr = make_expr(cell->getPort(ID::A));
wire_decls.push_back(stringf("%swire %s: UInt<%d> %s\n", indent.c_str(), y_id.c_str(), y_width, cellFileinfo.c_str()));
if (a_signed) {
a_expr = "asSInt(" + a_expr + ")";
}
// Don't use the results of logical operations (a single bit) to control padding
if (!(cell->type.in(ID($eq), ID($eqx), ID($gt), ID($ge), ID($lt), ID($le), ID($ne), ID($nex), ID($reduce_bool), ID($logic_not)) && y_width == 1) ) {
a_expr = stringf("pad(%s, %d)", a_expr.c_str(), y_width);
}
// Assume the FIRRTL width is a single bit.
firrtl_width = 1;
if (cell->type.in(ID($not), ID($_NOT_))) primop = "not";
else if (cell->type == ID($neg)) {
primop = "neg";
firrtl_is_signed = true; // Result of "neg" is signed (an SInt).
firrtl_width = a_width;
} else if (cell->type == ID($logic_not)) {
primop = "eq";
a_expr = stringf("%s, UInt(0)", a_expr.c_str());
}
else if (cell->type == ID($reduce_and)) primop = "andr";
else if (cell->type == ID($reduce_or)) primop = "orr";
else if (cell->type == ID($reduce_xor)) primop = "xorr";
else if (cell->type == ID($reduce_xnor)) {
primop = "not";
a_expr = stringf("xorr(%s)", a_expr.c_str());
}
else if (cell->type == ID($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 <= %s %s\n", indent.c_str(), y_id.c_str(), expr.c_str(), cellFileinfo.c_str()));
register_reverse_wire_map(y_id, cell->getPort(ID::Y));
continue;
}
if (cell->type.in(ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($xor), ID($_XOR_), ID($xnor), ID($and), ID($_AND_), ID($or), ID($_OR_), ID($eq), ID($eqx),
ID($gt), ID($ge), ID($lt), ID($le), ID($ne), ID($nex), ID($shr), ID($sshr), ID($sshl), ID($shl),
ID($logic_and), ID($logic_or), ID($pow)))
{
string a_expr = make_expr(cell->getPort(ID::A));
string b_expr = make_expr(cell->getPort(ID::B));
std::string cellFileinfo = getFileinfo(cell);
wire_decls.push_back(stringf("%swire %s: UInt<%d> %s\n", indent.c_str(), y_id.c_str(), y_width, cellFileinfo.c_str()));
if (a_signed) {
a_expr = "asSInt(" + a_expr + ")";
// Expand the "A" operand to the result width
if (a_width < y_width) {
a_expr = stringf("pad(%s, %d)", a_expr.c_str(), y_width);
a_width = y_width;
}
}
// Shift amount is always unsigned, and needn't be padded to result width,
// otherwise, we need to cast the b_expr appropriately
if (b_signed && !cell->type.in(ID($shr), ID($sshr), ID($shl), ID($sshl), ID($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(ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($xor), ID($_XOR_), ID($xnor), ID($and), ID($_AND_), ID($or), ID($_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(ID::A);
if (cell->type == ID($add)) {
primop = "add";
firrtl_is_signed = a_signed | b_signed;
firrtl_width = max(a_width, b_width);
} else if (cell->type == ID($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 == ID($mul)) {
primop = "mul";
firrtl_is_signed = a_signed | b_signed;
firrtl_width = a_width + b_width;
} else if (cell->type == ID($div)) {
primop = "div";
firrtl_is_signed = a_signed | b_signed;
firrtl_width = a_width;
} else if (cell->type == ID($mod)) {
// "rem" = truncating modulo
primop = "rem";
firrtl_width = min(a_width, b_width);
} else if (cell->type.in(ID($and), ID($_AND_))) {
primop = "and";
always_uint = true;
firrtl_width = max(a_width, b_width);
}
else if (cell->type.in(ID($or), ID($_OR_))) {
primop = "or";
always_uint = true;
firrtl_width = max(a_width, b_width);
}
else if (cell->type.in(ID($xor), ID($_XOR_))) {
primop = "xor";
always_uint = true;
firrtl_width = max(a_width, b_width);
}
else if (cell->type == ID($xnor)) {
primop = "xnor";
always_uint = true;
firrtl_width = max(a_width, b_width);
}
else if ((cell->type == ID($eq)) || (cell->type == ID($eqx))) {
primop = "eq";
always_uint = true;
firrtl_width = 1;
}
else if ((cell->type == ID($ne)) || (cell->type == ID($nex))) {
primop = "neq";
always_uint = true;
firrtl_width = 1;
}
else if (cell->type == ID($gt)) {
primop = "gt";
always_uint = true;
firrtl_width = 1;
}
else if (cell->type == ID($ge)) {
primop = "geq";
always_uint = true;
firrtl_width = 1;
}
else if (cell->type == ID($lt)) {
primop = "lt";
always_uint = true;
firrtl_width = 1;
}
else if (cell->type == ID($le)) {
primop = "leq";
always_uint = true;
firrtl_width = 1;
}
else if ((cell->type == ID($shl)) || (cell->type == ID($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(ID::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 == ID($shr)) || (cell->type == ID($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(ID::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 == ID($shr)) {
a_expr = "asUInt(" + a_expr + ")";
}
}
}
else if ((cell->type == ID($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 == ID($logic_or))) {
primop = "or";
a_expr = "neq(" + a_expr + ", UInt(0))";
b_expr = "neq(" + b_expr + ", UInt(0))";
always_uint = true;
firrtl_width = 1;
}
else if ((cell->type == ID($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(ID::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));
}
}
auto it = cell->parameters.find(ID::B_SIGNED);
if (it == cell->parameters.end() || !it->second.as_bool()) {
b_expr = "asUInt(" + b_expr + ")";
}
string expr;
// Deal with $xnor == ~^ (not xor)
if (primop == "xnor") {
expr = stringf("not(xor(%s, %s))", a_expr.c_str(), b_expr.c_str());
} else {
expr = stringf("%s(%s, %s)", primop.c_str(), a_expr.c_str(), b_expr.c_str());
}
// Deal with FIRRTL's "shift widens" semantics, or the need to widen the FIRRTL result.
// If the operation is signed, the FIRRTL width will be 1 one bit larger.
if (extract_y_bits) {
expr = stringf("bits(%s, %d, 0)", expr.c_str(), y_width - 1);
} else if (firrtl_is_signed && (firrtl_width + 1) < y_width) {
expr = stringf("pad(%s, %d)", expr.c_str(), y_width);
}
if ((firrtl_is_signed && !always_uint))
expr = stringf("asUInt(%s)", expr.c_str());
cell_exprs.push_back(stringf("%s%s <= %s %s\n", indent.c_str(), y_id.c_str(), expr.c_str(), cellFileinfo.c_str()));
register_reverse_wire_map(y_id, cell->getPort(ID::Y));
continue;
}
if (cell->type.in(ID($mux), ID($_MUX_)))
{
auto it = cell->parameters.find(ID::WIDTH);
int width = it == cell->parameters.end()? 1 : it->second.as_int();
string a_expr = make_expr(cell->getPort(ID::A));
string b_expr = make_expr(cell->getPort(ID::B));
string s_expr = make_expr(cell->getPort(ID::S));
wire_decls.push_back(stringf("%swire %s: UInt<%d> %s\n", indent.c_str(), y_id.c_str(), width, cellFileinfo.c_str()));
string expr = stringf("mux(%s, %s, %s)", s_expr.c_str(), b_expr.c_str(), a_expr.c_str());
cell_exprs.push_back(stringf("%s%s <= %s %s\n", indent.c_str(), y_id.c_str(), expr.c_str(), cellFileinfo.c_str()));
register_reverse_wire_map(y_id, cell->getPort(ID::Y));
continue;
}
if (cell->is_mem_cell())
{
// Will be handled below, as part of a Mem.
continue;
}
if (cell->type.in(ID($dff)))
{
bool clkpol = cell->parameters.at(ID::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(ID::WIDTH).as_int();
string expr = make_expr(cell->getPort(ID::D));
string clk_expr = "asClock(" + make_expr(cell->getPort(ID::CLK)) + ")";
wire_decls.push_back(stringf("%sreg %s: UInt<%d>, %s %s\n", indent.c_str(), y_id.c_str(), width, clk_expr.c_str(), cellFileinfo.c_str()));
cell_exprs.push_back(stringf("%s%s <= %s %s\n", indent.c_str(), y_id.c_str(), expr.c_str(), cellFileinfo.c_str()));
register_reverse_wire_map(y_id, cell->getPort(ID::Q));
continue;
}
if (cell->type == ID($shiftx)) {
// assign y = a[b +: y_width];
// We'll extract the correct bits as part of the primop.
string a_expr = make_expr(cell->getPort(ID::A));
// Get the initial bit selector
string b_expr = make_expr(cell->getPort(ID::B));
wire_decls.push_back(stringf("%swire %s: UInt<%d>\n", indent.c_str(), y_id.c_str(), y_width));
if (cell->getParam(ID::B_SIGNED).as_bool()) {
// Use validif to constrain the selection (test the sign bit)
auto b_string = b_expr.c_str();
int b_sign = cell->parameters.at(ID::B_WIDTH).as_int() - 1;
b_expr = stringf("validif(not(bits(%s, %d, %d)), %s)", b_string, b_sign, b_sign, b_string);
}
string expr = stringf("dshr(%s, %s)", a_expr.c_str(), b_expr.c_str());
cell_exprs.push_back(stringf("%s%s <= %s\n", indent.c_str(), y_id.c_str(), expr.c_str()));
register_reverse_wire_map(y_id, cell->getPort(ID::Y));
continue;
}
if (cell->type == ID($shift)) {
// assign y = a >> b;
// where b may be negative
string a_expr = make_expr(cell->getPort(ID::A));
string b_expr = make_expr(cell->getPort(ID::B));
auto b_string = b_expr.c_str();
string expr;
wire_decls.push_back(stringf("%swire %s: UInt<%d>\n", indent.c_str(), y_id.c_str(), y_width));
if (cell->getParam(ID::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 <= %s\n", indent.c_str(), y_id.c_str(), expr.c_str()));
register_reverse_wire_map(y_id, cell->getPort(ID::Y));
continue;
}
if (cell->type == ID($pos)) {
// assign y = a;
// printCell(cell);
string a_expr = make_expr(cell->getPort(ID::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("%swire %s: UInt<%d>\n", indent.c_str(), y_id.c_str(), y_width));
cell_exprs.push_back(stringf("%s%s <= %s\n", indent.c_str(), y_id.c_str(), a_expr.c_str()));
register_reverse_wire_map(y_id, cell->getPort(ID::Y));
continue;
}
log_error("Cell type not supported: %s (%s.%s)\n", log_id(cell->type), log_id(module), log_id(cell));
}
for (auto &mem : memories) {
string mem_id = make_id(mem.memid);
Const init_data = mem.get_init_data();
if (!init_data.is_fully_undef())
log_error("Memory with initialization data: %s.%s\n", log_id(module), log_id(mem.memid));
if (mem.start_offset != 0)
log_error("Memory with nonzero offset: %s.%s\n", log_id(module), log_id(mem.memid));
for (int i = 0; i < GetSize(mem.rd_ports); i++)
{
auto &port = mem.rd_ports[i];
string port_name(stringf("%s.r%d", mem_id.c_str(), i));
if (port.clk_enable)
log_error("Clocked read port %d on memory %s.%s.\n", i, log_id(module), log_id(mem.memid));
std::ostringstream rpe;
string addr_expr = make_expr(port.addr);
string ena_expr = make_expr(State::S1);
string clk_expr = make_expr(State::S0);
rpe << stringf("%s%s.addr <= %s\n", indent.c_str(), port_name.c_str(), addr_expr.c_str());
rpe << stringf("%s%s.en <= %s\n", indent.c_str(), port_name.c_str(), ena_expr.c_str());
rpe << stringf("%s%s.clk <= asClock(%s)\n", indent.c_str(), port_name.c_str(), clk_expr.c_str());
cell_exprs.push_back(rpe.str());
register_reverse_wire_map(stringf("%s.data", port_name.c_str()), port.data);
}
for (int i = 0; i < GetSize(mem.wr_ports); i++)
{
auto &port = mem.wr_ports[i];
string port_name(stringf("%s.w%d", mem_id.c_str(), i));
if (!port.clk_enable)
log_error("Unclocked write port %d on memory %s.%s.\n", i, log_id(module), log_id(mem.memid));
if (!port.clk_polarity)
log_error("Negedge write port %d on memory %s.%s.\n", i, log_id(module), log_id(mem.memid));
for (int i = 1; i < GetSize(port.en); i++)
if (port.en[0] != port.en[i])
log_error("Complex write enable on port %d on memory %s.%s.\n", i, log_id(module), log_id(mem.memid));
std::ostringstream wpe;
string data_expr = make_expr(port.data);
string addr_expr = make_expr(port.addr);
string ena_expr = make_expr(port.en[0]);
string clk_expr = make_expr(port.clk);
string mask_expr = make_expr(State::S1);
wpe << stringf("%s%s.data <= %s\n", indent.c_str(), port_name.c_str(), data_expr.c_str());
wpe << stringf("%s%s.addr <= %s\n", indent.c_str(), port_name.c_str(), addr_expr.c_str());
wpe << stringf("%s%s.en <= %s\n", indent.c_str(), port_name.c_str(), ena_expr.c_str());
wpe << stringf("%s%s.clk <= asClock(%s)\n", indent.c_str(), port_name.c_str(), clk_expr.c_str());
wpe << stringf("%s%s.mask <= %s\n", indent.c_str(), port_name.c_str(), mask_expr.c_str());
cell_exprs.push_back(wpe.str());
}
std::ostringstream me;
me << stringf(" mem %s:\n", mem_id.c_str());
me << stringf(" data-type => UInt<%d>\n", mem.width);
me << stringf(" depth => %d\n", mem.size);
for (int i = 0; i < GetSize(mem.rd_ports); i++)
me << stringf(" reader => r%d\n", i);
for (int i = 0; i < GetSize(mem.wr_ports); i++)
me << stringf(" writer => w%d\n", i);
me << stringf(" read-latency => %d\n", 0);
me << stringf(" write-latency => %d\n", 1);
me << stringf(" read-under-write => undefined\n");
mem_exprs.push_back(me.str());
}
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("%swire %s: UInt<%d>\n", indent.c_str(), y_id.c_str(), y_width));
cell_exprs.push_back(stringf("%s%s <= %s\n", indent.c_str(), y_id.c_str(), expr.c_str()));
register_reverse_wire_map(y_id, conn.first);
}
for (auto wire : module->wires())
{
string expr;
std::string wireFileinfo = getFileinfo(wire);
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("%swire %s: UInt<1> %s\n", indent.c_str(), unconn_id.c_str(), wireFileinfo.c_str()));
// `invalid` is a firrtl construction for simulation so we will not
// tag it with a @[fileinfo] tag as it doesn't directly correspond to
// a specific line of verilog code.
wire_decls.push_back(stringf("%s%s is invalid\n", indent.c_str(), unconn_id.c_str()));
}
wire_exprs.push_back(stringf("%s%s <= %s %s\n", indent.c_str(), make_id(wire->name), expr.c_str(), wireFileinfo.c_str()));
} else {
if (make_unconn_id) {
unconn_id.clear();
}
// `invalid` is a firrtl construction for simulation so we will not
// tag it with a @[fileinfo] tag as it doesn't directly correspond to
// a specific line of verilog code.
wire_decls.push_back(stringf("%s%s is invalid\n", indent.c_str(), make_id(wire->name)));
}
}
for (auto str : port_decls)
f << str;
f << stringf("\n");
for (auto str : wire_decls)
f << str;
f << stringf("\n");
for (auto str : mem_exprs)
f << str;
f << stringf("\n");
for (auto str : cell_exprs)
f << str;
f << stringf("\n");
for (auto str : wire_exprs)
f << str;
f << stringf("\n");
}
void run()
{
emit_module();
}
};
struct FirrtlBackend : public Backend {
FirrtlBackend() : Backend("firrtl", "write design to a FIRRTL file") { }
void help() 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(" bmuxmap\n");
log(" demuxmap\n");
log(" bwmuxmap\n");
log("\n");
}
void execute(std::ostream *&f, std::string filename, std::vector<std::string> args, RTLIL::Design *design) 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, "pmuxtree");
Pass::call(design, "bmuxmap");
Pass::call(design, "demuxmap");
Pass::call(design, "bwmuxmap");
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(ID::top)) {
top = module;
}
for (auto wire : module->wires())
if (wire->port_id)
make_id(wire->name);
}
if (top == nullptr)
top = last;
if (!top)
log_cmd_error("There is no top module in this design!\n");
std::string circuitFileinfo = getFileinfo(top);
*f << stringf("circuit %s: %s\n", make_id(top->name), circuitFileinfo.c_str());
emit_elaborated_extmodules(design, *f);
// Emit non-blackbox modules.
for (auto module : design->modules())
{
if (!module->get_blackbox_attribute())
{
FirrtlWorker worker(module, *f, design);
worker.run();
}
}
namecache.clear();
autoid_counter = 0;
}
} FirrtlBackend;
PRIVATE_NAMESPACE_END
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