diff options
Diffstat (limited to 'machxo2/cells.cc')
| -rw-r--r-- | machxo2/cells.cc | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/machxo2/cells.cc b/machxo2/cells.cc index 20e68ab5..7d15b1af 100644 --- a/machxo2/cells.cc +++ b/machxo2/cells.cc @@ -154,15 +154,24 @@ void lut_to_lc(const Context *ctx, CellInfo *lut, CellInfo *lc, bool no_dff) replace_port(lut, ctx->id("Z"), lc, ctx->id("F0")); } -void dff_to_lc(const Context *ctx, CellInfo *dff, CellInfo *lc, bool pass_thru_lut) +void dff_to_lc(Context *ctx, CellInfo *dff, CellInfo *lc, bool pass_thru_lut) { // FIXME: This will have to change once we support FFs with reset value of 1. lc->params[ctx->id("REG0_REGSET")] = std::string("RESET"); replace_port(dff, ctx->id("CLK"), lc, ctx->id("CLK")); - replace_port(dff, ctx->id("DI"), lc, ctx->id("DI0")); replace_port(dff, ctx->id("LSR"), lc, ctx->id("LSR")); replace_port(dff, ctx->id("Q"), lc, ctx->id("Q0")); + + // If a register's DI port is fed by a constant, options for placing are + // limited. Use the LUT to get around this. + if(pass_thru_lut) { + lc->params[ctx->id("LUT0_INITVAL")] = 0xAAAA; + replace_port(dff, ctx->id("DI"), lc, ctx->id("A0")); + connect_ports(ctx, lc, ctx->id("F0"), lc, ctx->id("DI0")); + } else { + replace_port(dff, ctx->id("DI"), lc, ctx->id("DI0")); + } } void nxio_to_iob(Context *ctx, CellInfo *nxio, CellInfo *iob, std::unordered_set<IdString> &todelete_cells) {} |