Services and Modeling for Embedded Software Development
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5.2.7.  Invoking the main program

The final stage is to call the main program. In this simple implementation there is no mechanism to pass arguments or environments to main, so the arguments argc, argv and env (in r3, r4 and r5) are set to 0, NULL and NULL respectively.

        l.or    r3,r0,r0
        l.or    r4,r0,r0
        l.jal   _main
        l.or    r5,r0,r0                /* Delay slot */

If the main program returns, its result (held in r11 on the OpenRISC 1000 ) will be a return code from the program, which we pass to the exit.

        l.jal   _exit
        l.addi  r3,r11,0                /* Delay slot */

exit should not return, but just in case, we can put the processor in a tight loop at this stage, in order to ensure consistent behavior.

        l.j     .L2
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