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

    Purpose:          Return from called procedure
    Format:           opcode
    Operation:        {restore SP from FP}; {restore registers};
                      {drop stack alignment};
                      {if CALLS, remove arglist}; {restore PSW}
    C. Codes:         N = tmp1<3>, Z = tmp1<2>, V = tmp1<1>,
                      C = tmp1<0>
    Exceptions:       Reserved operand
    Opcode:           04    RET      Return from procedure
    Description:    SP is replaced with FP plus 4. A longword containing
                    stack alignment in bits 31:30, a CALLS/CALLG flag in
                    bit 29, the low 12 bits of the procedure entry mask
                    in bits 27:16 and a saved PSW in bits 15:0 is popped
                    from the stack and saved in a temporary (tmp1). PC,
                    FP and AP are replaced by longwords popped from the
                    stack. A register restore mask is formed from bits
                    27:16 of tmp1. Scanning from bit 0 to bit 11 of tmp1,
                    the contents of the registers whose numbers are
                    indicated by set bits in the restore mask are
                    replaced by longwords popped from the stack. SP is
                    incremented by bits 31:30 of tmp1. PSW is replaced by
                    bits 15:0 of tmp1. If bit 29 of tmp1 is 1 (indicating
                    a CALLS was used) a longword containing the number of
                    arguments is popped from the stack. Four times the
                    unsigned value of the low byte of this longword is
                    added to SP and SP is replaced by the result.