/sys$common/syshlp/helplib.hlb MACRO, VAX MACRO Assembler, Instructions, ADAWI  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Purpose:        Add aligned word interlocked - maintain operating
                    system resource usage counts
    Format:         opcode add.rw,sum.mw
    Operation:      tmp = add; {set interlock}; sum = sum + tmp;
                    {release interlock}
    C. Codes:       N = {sum LSS 0}, Z = {sum EQL 0},
                    V = {integer overflow}, C = {carry from MSB}
    Exceptions:     Reserved operand fault, integer overflow
    Opcode:         58    ADAWI    Add aligned word interlocked
    Description:    The add operand is added to sum and sum is replaced
                    by the result. The operation is interlocked against
                    ADAWI operations by other processors or devices in
                    the system. The destination must be aligned on a
                    word boundary, i.e. bit zero of sum's address must
                    be zero. A reserved operand fault is taken if it
                    is not.