Subversion Repositories or1k

        .globl _start
        #
        # NOTE: Registers r10-r11 are reserved for the interrupt handler
        #       while the others can be used by the main loop/start code.

_start:         
        # patch the DBT handler
        add r1, r0, handler
        ldw r2, @(r1, 0)
        ldw r3, @(r1, 4)
        # DBT vector address
        add r1, r0, 0xfffff120
        stw r2, @(r1, 0)
        stw r3, @(r1, 4)

        # try out the breakpoint/return
        add r2, r0, 47
        #dbt
        nop
        .long 0x00b00000
        nop

        # exit with what ever the breakpoint hander set r2 to.
        nop
        .long 0x0e000004
        nop

handler:
        jmp real_handler
        
        # The Breakpoint handler sets r2 to 0 if PSW was set correctly.
real_handler:
        mvfsys r2, cr0
        sub r2, r0, 0x08000000
        #rtd
        nop
        .long 0x00a00000
        nop