User guide

18-8
DirectC Interface
small_bit_vector
Specifies a bit-width of a returned vector bit. A C/C++ function
cannot return a four state vector reg but it can return a vector
bit if its bit-width is 32 bits or less.
function_id
The name of the C/C++ function.
direction
One of the following keywords: input, output, inout. These
keywords specify in a C/C++ function the same thing that they
specify in a Verilog task; see Table 18-2.
arg_type
The valid argument types are real, reg, bit, int, pointer,
string.
[bit_width]
Specifies the bit-width of a vector reg or bit that is an argument
to the C/C++ function. You can leave the bit-width open by
entering [].
array
Specifies that the argument is a Verilog memory.
[index_range]
Specifies a range of elements (words, addresses) in the memory.
You can leave the range open by entering [].
arg_id
The Verilog register argument to the C/C++ function that becomes
the actual parameter to the function.