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ecp5: Improve handling of constant CCU2C inputs

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Signed-off-by: David Shah <davey1576@gmail.com>
This commit is contained in:
David Shah 2018-10-01 14:42:19 +01:00
parent e7c8818424
commit 931c78b1bb
1 changed files with 65 additions and 9 deletions
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74
ecp5/pack.cc
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@ -637,14 +637,12 @@ class Ecp5Packer
flush_cells();
}
void set_lut_input_constant(CellInfo *cell, IdString input, bool value)
int make_init_with_const_input(int init, int input, bool value)
{
int index = std::string("ABCD").find(input.str(ctx));
int init = int_or_default(cell->params, ctx->id("INIT"));
int new_init = 0;
for (int i = 0; i < 16; i++) {
if (((i >> index) & 0x1) != value) {
int other_i = (i & (~(1 << index))) | (value << index);
if (((i >> input) & 0x1) != value) {
int other_i = (i & (~(1 << input))) | (value << input);
if ((init >> other_i) & 0x1)
new_init |= (1 << i);
} else {
@ -652,10 +650,41 @@ class Ecp5Packer
new_init |= (1 << i);
}
}
return new_init;
}
void set_lut_input_constant(CellInfo *cell, IdString input, bool value)
{
int index = std::string("ABCD").find(input.str(ctx));
int init = int_or_default(cell->params, ctx->id("INIT"));
int new_init = make_init_with_const_input(init, index, value);
cell->params[ctx->id("INIT")] = std::to_string(new_init);
cell->ports.at(input).net = nullptr;
}
void set_ccu2c_input_constant(CellInfo *cell, IdString input, bool value)
{
std::string input_str = input.str(ctx);
int lut = std::stoi(input_str.substr(1));
int index = std::string("ABCD").find(input_str[0]);
int init = int_or_default(cell->params, ctx->id("INIT" + std::to_string(lut)));
int new_init = make_init_with_const_input(init, index, value);
cell->params[ctx->id("INIT" + std::to_string(lut))] = std::to_string(new_init);
cell->ports.at(input).net = nullptr;
}
bool is_ccu2c_port_high(CellInfo *cell, IdString input)
{
if (!cell->ports.count(input))
return true; // disconnected port is high
if (cell->ports.at(input).net == nullptr || cell->ports.at(input).net->name == ctx->id("$PACKER_VCC_NET"))
return true; // disconnected or tied-high port
if (cell->ports.at(input).net->driver.cell != nullptr &&
cell->ports.at(input).net->driver.cell->type == ctx->id("VCC"))
return true; // pre-pack high
return false;
}
// Merge a net into a constant net
void set_net_constant(const Context *ctx, NetInfo *orig, NetInfo *constnet, bool constval)
{
@ -670,10 +699,37 @@ class Ecp5Packer
} 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_carry(ctx, uc) && constval &&
(user.port == id_A0 || user.port == id_A1 || user.port == id_B0 || user.port == id_B1 ||
user.port == id_C0 || user.port == id_C1 || user.port == id_D0 || user.port == id_D1)) {
uc->ports[user.port].net = nullptr;
} else if (is_carry(ctx, uc)) {
if (constval &&
(user.port == id_A0 || user.port == id_A1 || user.port == id_B0 || user.port == id_B1 ||
user.port == id_C0 || user.port == id_C1 || user.port == id_D0 || user.port == id_D1)) {
// Input tied high, nothing special to do (bitstream gen will auto-enable tie-high)
uc->ports[user.port].net = nullptr;
} else if (!constval) {
if (user.port == id_A0 || user.port == id_A1 || user.port == id_B0 || user.port == id_B1) {
// These inputs can be switched to tie-high without consequence
set_ccu2c_input_constant(uc, user.port, constval);
} else if (user.port == id_C0 && is_ccu2c_port_high(uc, id_D0)) {
// Partner must be tied high
set_ccu2c_input_constant(uc, user.port, constval);
} else if (user.port == id_D0 && is_ccu2c_port_high(uc, id_C0)) {
// Partner must be tied high
set_ccu2c_input_constant(uc, user.port, constval);
} else if (user.port == id_C1 && is_ccu2c_port_high(uc, id_D1)) {
// Partner must be tied high
set_ccu2c_input_constant(uc, user.port, constval);
} else if (user.port == id_D1 && is_ccu2c_port_high(uc, id_C1)) {
// Partner must be tied high
set_ccu2c_input_constant(uc, user.port, constval);
} else {
// Not allowed to change to a tie-high
uc->ports[user.port].net = constnet;
constnet->users.push_back(user);
}
} else {
uc->ports[user.port].net = constnet;
constnet->users.push_back(user);
}
} 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"))) {