Fortress

А что эти операции должны делать? Семантика?

Выдержка из стандарта языка Verilog 2005:

The unary reduction operators shall perform a bitwise operation on a single operand to produce a single-bit
result. For reduction and, reduction or, and reduction xor operators, the first step of the operation shall apply
the operator between the first bit of the operand and the second.
The second and subsequent steps shall apply the operator between the 1-bit result of the prior step and the
next bit of the operand using the same logic table. For reduction nand, reduction nor, and reduction xnor
operators, the result shall be computed by inverting the result of the reduction and, reduction or, and
reduction xor operation, respectively.