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

    Purpose:        Move character string or block of memory
    Format:         opcode len.rw,srcaddr.ab,dstaddr.ab         ;3 operand
                    opcode srclen.rw,srcaddr.ab,fill.rb,        ;5 operand
                           dstlen.rw,dstaddr.ab
    Operation:      {dst string} = {src string}
    Exceptions:     None
    Opcodes:        28    MOVC3    Move character 3 operand
                    2C    MOVC5    Move character 5 operand
    Description:    dst as specified by dstaddr and len (3 operand) or
                    dstlen (5 operand) is replaced by src as specified by
                    srcaddr and len (3 operand) or srclen (5 operand). If
                    dst is longer than src (5 operand only), the highest
                    addresses of dst that are not filled by src are
                    instead filled with fill. If dst is shorter than src,
                    the copied string is truncated to fit in src. The
                    operation of the instruction is such that any overlap
                    of src and dst will not affect the result.
    Notes:          After execution of MOVC3:

                    R0 = 0
                    R1 = address of one byte beyond the source string
                    R2 = 0
                    R3 = address of one byte beyond the destination string
                    R4 = 0
                    R5 = 0

                    After execution of MOVC5:

                    R0 = number of unmoved bytes remaining in the
                         source string. R0 is nonzero only if source
                         string is longer than the destination string
                    R1 = address of one byte beyond the last byte in
                         source string that was moved
                    R2 = 0
                    R3 = address of one byte beyond the destination string
                    R4 = 0
                    R5 = 0