探讨一下ARM以及RVDS的使用

; On reset, an aliased copy of ROM is at 0x0.

        LDR     pc, =Instruct_2

        

Instruct_2        



; Remap by setting Remap bit of the CM_ctl register

        LDR     r1, =CM_ctl_reg

        LDR     r0, [r1]

        ORR     r0, r0, #Remap_bit

        STR     r0, [r1]

        

; RAM is now at 0x0.

; The exception vectors (in vectors.s) must be copied from ROM to the RAM

; The copying is done later by the C library code inside __main



    ENDIF



;EXPORT  Reset_Handler



Reset_Handler



; --- Initialize stack pointer registers



; Enter each mode in turn and set up the stack pointer



        IMPORT  top_of_stacks       ; defined in stack.s and located by scatter file

        LDR     r0, =top_of_stacks



        MSR     CPSR_c, #Mode_FIQ:OR:I_Bit:OR:F_Bit ; No interrupts

        SUB     sp, r0, #Offset_FIQ_Stack



        MSR     CPSR_c, #Mode_IRQ:OR:I_Bit:OR:F_Bit ; No interrupts

        SUB     sp, r0, #Offset_IRQ_Stack



       MSR     CPSR_c, #Mode_ABT:OR:I_Bit:OR:F_Bit ; No interrupts

       SUB     sp, r0, #Offset_ABT_Stack



       MSR     CPSR_c, #Mode_UND:OR:I_Bit:OR:F_Bit ; No interrupts

       SUB     sp, r0, #Offset_UND_Stack



        MSR     CPSR_c, #Mode_SVC:OR:I_Bit:OR:F_Bit ; No interrupts

        SUB     sp, r0, #Offset_SVC_Stack



; --- Now change to User mode and set up User mode stack, if needed

        MSR     CPSR_c, #Mode_USR:OR:I_Bit:OR:F_Bit ; No interrupts

        SUB     sp, r0, #Offset_USR_Stack

                

        IMPORT  main



; --- Now enter C code

        B       main  ; note use B not BL, because an application will never return this way

typedef struct xd_struct {

   uint_8         MAX_PKTS_PER_UFRAME;

   void           (*p_fn_callback)(uchar_ptr);

   uint_8      CTL;           /* USB Endpoint Control byte */

   uint_8      NEXTODDEVEN;   /* Odd/Even of Next BDT to queue */

   uint_8      LASTODDEVEN;   /* Odd/Even of Last BDT used */

} XD_STRUCT, _PTR_ XD_STRUCT_PTR;