VMS Help MACRO, VAX MACRO Assembler, Instructions, CVTSP  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Purpose:        Convert a leading separate numeric string to packed
                    decimal
    Format:         opcode srclen.rw,srcaddr.ab,dstlen.rw,dstaddr.ab
    Operation:      {dst string} = conversion of {src string}
    C. Codes:       N = {{dst string} LSS 0}, V = {decimal overflow},
                    Z = {{dst string} EQL 0}, C = 0
    Exceptions:     Reserved operand, decimal overflow
    Opcode:         09    CVTSP    Convert leading separate to packed
    Description:    The source leading separate numeric string src
                    specified by srclen and srcaddr is converted to
                    a packed decimal string and the result is placed
                    in dst as specified by dstlen and dstaddr.
    Notes:          After execution:

                    R0 = 0
                    R1 = address of the sign byte of the source string
                    R2 = 0
                    R3 = address of the byte containing the
                         most-significant digit of the destination string