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Add flooring modulo operator

The $div and $mod cells use truncating division semantics (rounding
towards 0), as defined by e.g. Verilog. Another rounding mode, flooring
(rounding towards negative infinity), can be used in e.g. VHDL. The
new $modfloor cell provides this flooring modulo (also known as "remainder"
in several languages, but this name is ambiguous).

This commit also fixes the handling of $mod in opt_expr, which was
previously optimized as if it was $modfloor.
This commit is contained in:
Xiretza 2020-04-08 19:30:47 +02:00
parent 0d99522b3c
commit 17163cf43a
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GPG key ID: 17B78226F7139993
23 changed files with 280 additions and 37 deletions

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@ -103,7 +103,7 @@ bool cell_supported(RTLIL::Cell *cell)
if (sig_bi.is_fully_const() && sig_ci.is_fully_const() && sig_bi == sig_ci)
return true;
} else if (cell->type.in(LOGICAL_OPS, SHIFT_OPS, BITWISE_OPS, RELATIONAL_OPS, ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($concat))) {
} else if (cell->type.in(LOGICAL_OPS, SHIFT_OPS, BITWISE_OPS, RELATIONAL_OPS, ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($modfloor), ID($concat))) {
return true;
}
@ -130,7 +130,7 @@ bool mergeable(RTLIL::Cell *a, RTLIL::Cell *b)
RTLIL::IdString decode_port_semantics(RTLIL::Cell *cell, RTLIL::IdString port_name)
{
if (cell->type.in(ID($lt), ID($le), ID($ge), ID($gt), ID($div), ID($mod), ID($concat), SHIFT_OPS) && port_name == ID::B)
if (cell->type.in(ID($lt), ID($le), ID($ge), ID($gt), ID($div), ID($mod), ID($modfloor), ID($concat), SHIFT_OPS) && port_name == ID::B)
return port_name;
return "";