caiyu/nextpnr
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

ice40: More preparations for carry legalisation

Browse Source 
Signed-off-by: David Shah <davey1576@gmail.com>
This commit is contained in:
David Shah 2018-06-25 14:45:33 +02:00
parent fb5fb497b5
commit 8d9444b6f0
2 changed files with 80 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
ice40/cells.cc
View File

@ -47,6 +47,8 @@ CellInfo *create_ice_cell(Context *ctx, IdString type, std::string name)
new_cell->params[ctx->id("DFF_ENABLE")] = "0";
new_cell->params[ctx->id("SET_NORESET")] = "0";
new_cell->params[ctx->id("ASYNC_SR")] = "0";
new_cell->params[ctx->id("CIN_CONST")] = "0";
new_cell->params[ctx->id("CIN_SET")] = "0";
add_port(ctx, new_cell, "I0", PORT_IN);
add_port(ctx, new_cell, "I1", PORT_IN);

74
ice40/place_legaliser.cc
View File

@ -61,7 +61,8 @@ std::vector<std::vector<CellInfo *>> find_chains(const Context *ctx, F1 cell_typ
return chains;
}
static void get_chain_midpoint(const Context *ctx, const std::vector<CellInfo *> &chain, float &x, float &y) {
static void get_chain_midpoint(const Context *ctx, const std::vector<CellInfo *> &chain, float &x, float &y)
{
float total_x = 0, total_y = 0;
int N = 0;
for (auto cell : chain) {
@ -79,7 +80,35 @@ static void get_chain_midpoint(const Context *ctx, const std::vector<CellInfo *>
y = total_y / N;
}
static CellInfo *make_carry_pass_out(Context *ctx, PortInfo &cout_port) {
class PlacementLegaliser
{
public:
PlacementLegaliser(Context *ctx) : ctx(ctx){};
bool legalise()
{
bool legalised_carries = legalise_carries();
if (!legalised_carries && !ctx->force)
return false;
return legalised_carries;
}
private:
bool legalise_carries()
{
std::vector<std::vector<CellInfo *>> carry_chains = find_chains(
ctx, is_lc,
[](const Context *ctx, const CellInfo *cell) {
return net_driven_by(ctx, cell->ports.at(ctx->id("CIN")).net, is_lc, ctx->id("COUT"));
},
[](const Context *ctx, const CellInfo *cell) {
return net_only_drives(ctx, cell->ports.at(ctx->id("COUT")).net, is_lc, ctx->id("CIN"), false);
});
// TODO
return true;
}
CellInfo *make_carry_pass_out(PortInfo &cout_port)
{
assert(cout_port.net != nullptr);
CellInfo *lc = create_ice_cell(ctx, ctx->id("ICESTORM_LC"));
lc->params[ctx->id("LUT_INIT")] = "65280"; // 0xff00: O = I3
@ -96,21 +125,40 @@ static CellInfo *make_carry_pass_out(Context *ctx, PortInfo &cout_port) {
o_r.cell = lc;
cout_port.net->driver = o_r;
lc->ports.at(ctx->id("I3")).net = co_i3_net;
ctx->cells[lc->name] = lc;
createdCells.insert(lc->name);
return lc;
}
}
CellInfo *make_carry_feed_in(CellInfo *cin_cell, PortInfo &cin_port)
{
assert(cin_port.net != nullptr);
CellInfo *lc = create_ice_cell(ctx, ctx->id("ICESTORM_LC"));
lc->params[ctx->id("CARRY_ENABLE")] = "1";
lc->params[ctx->id("CIN_CONST")] = "1";
lc->params[ctx->id("CIN_SET")] = "1";
lc->ports.at(ctx->id("I1")).net = cin_port.net;
cin_port.net->users.erase(std::remove_if(cin_port.net->users.begin(), cin_port.net->users.end(),
[cin_cell, cin_port](const PortRef &usr) {
return usr.cell == cin_cell && usr.port == cin_port.name;
}));
NetInfo *out_net = new NetInfo();
out_net->name = ctx->id(lc->name.str(ctx) + "$O");
ctx->cells[lc->name] = lc;
createdCells.insert(lc->name);
return lc;
}
Context *ctx;
std::unordered_set<IdString> rippedCells;
std::unordered_set<IdString> createdCells;
};
bool legalise_design(Context *ctx)
{
std::vector<std::vector<CellInfo *>> carry_chains = find_chains(
ctx, is_lc,
[](const Context *ctx, const CellInfo *cell) {
return net_driven_by(ctx, cell->ports.at(ctx->id("CIN")).net, is_lc, ctx->id("COUT"));
},
[](const Context *ctx, const CellInfo *cell) {
return net_only_drives(ctx, cell->ports.at(ctx->id("COUT")).net, is_lc, ctx->id("CIN"), false);
});
// TODO
return true;
PlacementLegaliser lg(ctx);
return lg.legalise();
}
NEXTPNR_NAMESPACE_END