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

    Purpose:        Convert a packed decimal string to trailing numeric
    Format:         opcode srclen.rw,srcaddr.ab,tbladdr.ab,
                           dstlen.rw,dstaddr.ab
    Operation:      {dst string} = conversion of {src string}
    C. Codes:       N = {{src string} LSS 0}, V = {decimal overflow},
                    Z = {{src string} EQL 0}, C = 0
    Exceptions:     Reserved operand, decimal overflow
    Opcode:         24    CVTPT    Convert packed to trailing numeric
    Description:    The packed decimal source string src specified by
                    srclen and srcaddr is converted to a trailing
                    numeric string and the result is placed in dst as
                    specified by dstlen and dstaddr. Conversion is
                    effected by using the highest addressed byte of src
                    (i.e. the byte containing the sign and least
                    significant digit) as an unsigned index into a 256
                    byte table whose 0th entry is specified by tbladdr.
                    The byte read out of the table replaces the least
                    significant byte of dst. The remaining bytes of dst
                    are replaced by the ASCII representations of the
                    digits in src.
    Notes:          After execution:

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