Question

The $readmemb, $readmemh, $writememb, and $writememh signatures are shown below:

$readmemb("file_name", memory_name[, start_addr[, finish_addr]]);
$readmemh("file_name", memory_name[, start_addr[, finish_addr]]);
$writememb("file_name", memory_name[, start_addr[, finish_addr]]);
$writememh("file_name", memory_name[, start_addr[, finish_addr]]);

memory_name can be an unpacked array, or a partially indexed multi-dimensional unpacked array that resolves to a lesser-dimensioned unpacked array.

Higher order dimensions must be specified with an index, rather than a complete or partial dimension range. The lowest dimension (i.e. the right-most specified dimension in the identifier) can be specified with slice syntax. See Section 4.4 for details on legal array indexing in SystemVerilog.

The start_addr and finish_addr arguments apply to the addresses of the unpacked array selected by memory_name. This address range represents the highest dimension of data in the file_name.

When slice syntax is used in the memory_name argument, any start_addr and finish_addr arguments must fall within the bounds of the slice’s range.

The direction of the highest dimension’s file entries is given by the relative magnitudes of start_addr and finish_addr, as is the case in 1364-2001.