thumbsub.s

一些ARM的源程序

#        AREA ThumbSub, CODE, READONLY   ;  name this block of code
#        ENTRY                           ;  mark first instruction to execute
.text
.arm              			            /*  Subsequent instructions are ARM */
header:
        ADR     r0, start + 1           /*  Processor starts in ARM state, */
        BX      r0                      /*  so small ARM code header used */
                                    	/*  to call Thumb main program. */

        NOP
        NOP

.thumb
#        CODE16                          /*  Subsequent instructions are Thumb. */
start:
        MOV     r0, #10                 /*  Set up parameters */
        MOV     r1, #3
        BL      doadd                   /*  Call subroutine */

stop:
        MOV     r0, #0x18               /*  angel_SWIreason_ReportException */
        LDR     r1, =0x20026            /*  ADP_Stopped_ApplicationExit */
        SWI     0xAB                    /*  Angel semihosting Thumb SWI */

doadd:
        ADD     r0, r0, r1              /*  Subroutine code */
        MOV     pc, lr                  /*  Return from subroutine. */

.end                                 	/*  Mark end of file */