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ecp5: Add simple constant packer

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Signed-off-by: David Shah <davey1576@gmail.com>
This commit is contained in:
David Shah 2018-07-18 09:35:40 +02:00
parent edf7bd09cf
commit f138368e34
3 changed files with 98 additions and 2 deletions
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8
ecp5/archdefs.h
View File

@ -129,8 +129,12 @@ struct DecalId
}
};
struct ArchNetInfo { };
struct ArchCellInfo { };
struct ArchNetInfo
{
};
struct ArchCellInfo
{
};
NEXTPNR_NAMESPACE_END

8
ecp5/cells.cc
View File

@ -116,6 +116,14 @@ std::unique_ptr<CellInfo> create_ecp5_cell(Context *ctx, IdString type, std::str
add_port(ctx, new_cell.get(), "I", PORT_IN);
add_port(ctx, new_cell.get(), "T", PORT_IN);
add_port(ctx, new_cell.get(), "O", PORT_OUT);
} else if (type == ctx->id("LUT4")) {
new_cell->params[ctx->id("INIT")] = "0";
add_port(ctx, new_cell.get(), "A", PORT_IN);
add_port(ctx, new_cell.get(), "B", PORT_IN);
add_port(ctx, new_cell.get(), "C", PORT_IN);
add_port(ctx, new_cell.get(), "D", PORT_IN);
add_port(ctx, new_cell.get(), "Z", PORT_OUT);
} else {
log_error("unable to create ECP5 cell of type %s", type.c_str(ctx));
}

84
ecp5/pack.cc
View File

@ -385,10 +385,94 @@ class Ecp5Packer
cell->ports.at(input).net = nullptr;
}
// Merge a net into a constant net
void set_net_constant(const Context *ctx, NetInfo *orig, NetInfo *constnet, bool constval)
{
orig->driver.cell = nullptr;
for (auto user : orig->users) {
if (user.cell != nullptr) {
CellInfo *uc = user.cell;
if (ctx->verbose)
log_info("%s user %s\n", orig->name.c_str(ctx), uc->name.c_str(ctx));
if (is_lut(ctx, uc)) {
set_lut_input_constant(uc, user.port, constval);
} else if (is_ff(ctx, uc) && user.port == ctx->id("CE")) {
uc->params[ctx->id("CEMUX")] = constval ? "1" : "0";
uc->ports[user.port].net = nullptr;
} else if (is_ff(ctx, uc) && user.port == ctx->id("LSR") &&
((!constval && str_or_default(uc->params, ctx->id("LSRMUX"), "LSR") == "LSR") ||
(constval && str_or_default(uc->params, ctx->id("LSRMUX"), "LSR") == "INV"))) {
uc->ports[user.port].net = nullptr;
} else {
uc->ports[user.port].net = constnet;
constnet->users.push_back(user);
}
}
}
orig->users.clear();
}
// Pack constants (simple implementation)
void pack_constants()
{
log_info("Packing constants..\n");
std::unique_ptr<CellInfo> gnd_cell = create_ecp5_cell(ctx, ctx->id("LUT4"), "$PACKER_GND");
gnd_cell->params[ctx->id("LUT_INIT")] = "0";
std::unique_ptr<NetInfo> gnd_net = std::unique_ptr<NetInfo>(new NetInfo);
gnd_net->name = ctx->id("$PACKER_GND_NET");
gnd_net->driver.cell = gnd_cell.get();
gnd_net->driver.port = ctx->id("Z");
gnd_cell->ports.at(ctx->id("Z")).net = gnd_net.get();
std::unique_ptr<CellInfo> vcc_cell = create_ecp5_cell(ctx, ctx->id("LUT4"), "$PACKER_VCC");
vcc_cell->params[ctx->id("LUT_INIT")] = "65535";
std::unique_ptr<NetInfo> vcc_net = std::unique_ptr<NetInfo>(new NetInfo);
vcc_net->name = ctx->id("$PACKER_VCC_NET");
vcc_net->driver.cell = vcc_cell.get();
vcc_net->driver.port = ctx->id("Z");
vcc_cell->ports.at(ctx->id("Z")).net = vcc_net.get();
std::vector<IdString> dead_nets;
bool gnd_used = false, vcc_used = false;
for (auto net : sorted(ctx->nets)) {
NetInfo *ni = net.second;
if (ni->driver.cell != nullptr && ni->driver.cell->type == ctx->id("GND")) {
IdString drv_cell = ni->driver.cell->name;
set_net_constant(ctx, ni, gnd_net.get(), false);
gnd_used = true;
dead_nets.push_back(net.first);
ctx->cells.erase(drv_cell);
} else if (ni->driver.cell != nullptr && ni->driver.cell->type == ctx->id("VCC")) {
IdString drv_cell = ni->driver.cell->name;
set_net_constant(ctx, ni, vcc_net.get(), true);
vcc_used = true;
dead_nets.push_back(net.first);
ctx->cells.erase(drv_cell);
}
}
if (gnd_used) {
ctx->cells[gnd_cell->name] = std::move(gnd_cell);
ctx->nets[gnd_net->name] = std::move(gnd_net);
}
if (vcc_used) {
ctx->cells[vcc_cell->name] = std::move(vcc_cell);
ctx->nets[vcc_net->name] = std::move(vcc_net);
}
for (auto dn : dead_nets) {
ctx->nets.erase(dn);
}
}
public:
void pack()
{
pack_io();
pack_constants();
find_lutff_pairs();
pack_lut5s();
pair_luts();