lowlevel_init 的问题

.globl lowlevel_init
lowlevel_init:
 /* memory control configuration */
 /* make r0 relative the current location so that it */
 /* reads SMRDATA out of FLASH rather than memory ! */
 ldr     r0, =SMRDATA
 ldr r1, =lowlevel_init
 sub r0, r0, r1
 adr r3, lowlevel_init  /* r3 <- current position of code   */
 add     r0, r0, r3
 ldr r1, =BWSCON /* Bus Width Status Controller */
 add     r2, r0, #13*4
0:
 ldr     r3, [r0], #4
 str     r3, [r1], #4
 cmp     r2, r0
 bne     0b

 

ldr r1,=lowlevel_init   这下面几句是干什么的