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

    Purpose:        Insert entry into queue at head, interlocked
    Format:         opcode entry.ab,header.aq
    Operation:      if {insertion succeded} then
                    begin
                      N <- 0;
                      Z <- (entry) EQL (entry+4);   ! First entry in queue
                      V <- 0;
                      C <- 0;
                    end;
                    else
                    begin
                      N <- 0;
                      Z <- 0;
                      V <- 0;
                      C <- 1;                 ! Secondary interlock failed
                    end;
    Exceptions:     Reserved operand
    Opcode:         5C    INSQHI   Insert entry into queue at head, interlocked
    Description:    The entry specified by the operand entry is
                    inserted into the queue following the header
                    specified by pred. If the entry inserted is the
                    first one in the queue, the Z bit is set; otherwise
                    it is cleared. The insertion is a noninterruptable
                    operation. The entire operation is validated before
                    any portion of it is attempted. The queue will be
                    left in a consistent state if a memory management
                    violation occurs.