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

    Purpose:        To skip a set of characters in a string
    Format:         opcode len.rw,addr.ab,tbladdr.ab,mask.rb
    Operation:      {mask each character until zero}
    C. Codes:       N = 0, Z = {R0 EQL 0}, V = 0, C = 0
    Exceptions:     None
    Opcode:         2B    SPANC    Span characters
    Description:    The bytes of the string specified by addr and len are
                    used to index into a 256 byte table pointed to by
                    tbladdr. The byte selected from the table is ANDed
                    with mask. The operand proceeds until the result of
                    the AND is zero or all the bytes of the string have
                    been exhausted. If a zero AND result is detected, the
                    Z bit is cleared; otherwise, the Z bit is set.
    Notes:          After execution:

                    R0 = number of bytes remaining in the string
                         (including the byte that produced the
                         0 AND result); R0 is 0 only if
                         there was no 0 AND result
                    R1 = address of the byte that produced the
                         0 AND result, if no nonzero result,
                         address of  one byte beyond the string
                    R2 = 0
                    R3 = address of the table

                    If the string has 0 length, condition code Z is set
                    just as though the entire string were spanned