中断向量表LED test

.text.global _start_start:    b    reset    ldr  pc,_undefined_instruction    ldr  pc,_software_interrupt    ldr  pc,_prefetch_abort    ldr  pc,_data_abort    ldr  pc,_not_used    ldr  pc,_irq    ldr  pc,_fiq_undefined_instruction: .word _undefined_instruction_software_interrupt:    .word _software_interrupt_prefetch_abort:        .word _prefetch_abort_data_abort:            .word _data_abort_not_unsed:             .word _not_used_irq:                   .word irq_handler_fiq:                   .word _fiqreset:    ldr r0,=0x40008000    mcr p15,0,r0,c12,c0,0   @ Vector Base Address Register        mrs    r0,cpsr        bic    r0,r0,#0x1f        orr    r0,r0,#0xd3        msr    cpsr,r0      @ Enable svc mode of cpu        mov r0,#0xfffffff        mcr p15,0,r0,c1,c0,2  @ Defines access permissins for each coprocessor         /*         * Invalidate L1 I/D         */         mov r0,#0    @set up for MCR         mcr p15,0,r0,c8,c7,0   @invalidate TLBs         mcr p15,0,r0,c7,c5,0   @invalidate icache         @ Set the FPEXC EN bit to enable the FPU:         MOV r3,#0x40000000         fmxr FPEXC,r3         /*         * disable MMU stuff and caches         */         mrc r15,0,r0,c1,c0,0         bic r0,r0,#0x00002000 @ clear bits 13 (--V-)         bic r0,r0,#0x00000007 @ clear bits 2:0 (-CAM)         orr r0,r0,#0x00001000 @ set bit 12 (---I) Icache         orr r0,r0,#0x00000002 @ set bit 1  (--A-) Align         orr r0,r0,#0x00000800 @ set bit 11 (Z---) BTB         mcr p15,0,r0,c1,c0,0/*LED Test Code*/    ldr r0,=0x114001E0    ldr r1,[r0]    bic r1,r1,#0xf0000    orr r1,r1,#0x10000    str r1,[r0]    ldr r0,=0x114001E8    ldr r1,[r0]    bic r1,r1,#0x300    str r1,[r0]    ldr r0,=0x114001E4    ldr r1,[r0]    orr r1,r1,#0x10    str r1,[r0]init_stack:        ldr    r0,stacktop    /*get stack top pointer*/    /**********svc mode stack*************/        mov sp,r0        sub r0,#128*4    /*512 byte for irq mode of stack*/    /****irq mode stack**/        msr cpsr,#0xd2        mov sp,r0        sub r0,#128*4    /***fiq mode stack***/        msr cpsr,#0xdl        mov sp,r0        sub r0,#0    /***abort mode stack***/        msr cpsr,#0xd7        mov sp,r0        sub r0,#0    /***undefine mode stack***/        msr cpsr,#0xdb        mov sp,r0        sub r0,#0    /*** sys mode and usr mode stack ***/        msr cpsr,#0x10        mov sp,r0    /*1024 byte for user mode of stack*/        b main    .align 4    /**** swi_interrupt handler ****/irq_handler:    sub lr,lr,#4    stmfd sp!,{r0-r12,lr}//  bl do_irq    ldmfd sp!,{r0-r12,pc}^stacktop:    .word stack+4*512.datastack:   .apace 4*512