assemb.s

ADuC系列芯片的源代码事例

/*********************************************************************

 Author        : ADI - Apps            www.analog.com/MicroConverter

 Date          : Sept. 2005

 File          : assemb.s

 Hardware      : Applicable to ADuC702x rev H or I silicon
                 Currently targetting ADuC7026.

 Description   : Blink_Setup enables P4.2 as an output.
 				 Blink takes the value passed too it by the C code, 
				 which is passed in R0 as per APCS Spec., and 
				 compliments P4.2. 
				 assemb is compiled in ARM by default.

				 If desired, you may return a value in R0 to the C file.

Note:			 For more complex examples you will be required to
				 save any registers you corrupt onto the stack. 
				 		
*********************************************************************/
.include "ADuC7026.equ"

.ARM								@ Delcare this code to be assembled as ARM

.GLOBL Blink_Setup   				@ declare Blink_Setup as global	for linking
Blink_Setup:						
		ldr		r5, =GPIOBASE		@ Load the GPIOBASE MMR Location into R5
		mov		r7, #0x04000000		@ Value required to enable P4.2 as an output
		str		r7, [r5, #0x60]		@ Enable P4.2 as output

		bx		lr 					@ return      	

.GLOBL Blink						@ declare Blink as global for linking
Blink:	

Blink_Del:
		subs    r0,r0,#1		 	@ Decrement Delay Value, Set Flags
    	bne     Blink_Del			@ If zero, continue

		mov	r2, #-1560281088
		mov	r2, r2, asr #19			@ R2 now contains GP4DAT address
		ldr	r3, [r2, #0]			@ Get current value
		eor	r3, r3, #262144			@ XOR it to cause complimenting
		str	r3, [r2, #0]			@ Write value to GP4DAT

		bx		lr 					@ return