J.P. Armstrong / Mbed 2 deprecated IntToBinaryAssembly

Assembly procedure that represents binary using the LEDs on the mbed.

Dependencies:   mbed

binasm.s@2:a81c9bc37084, 2011-01-28 (annotated)

Committer:
jp
Date:
Fri Jan 28 02:40:35 2011 +0000
Revision:
2:a81c9bc37084
Parent:
0:13e4e935bed6 

        

        
Who changed what in which revision?

        

            
                
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 AREA |.data|, DATA, READWRITE





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 EXPORT leds





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;BIT MASKS FOR LED1...LED4





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LED1 EQU 0x040000 





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LED2 EQU 0x100000





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LED3 EQU 0x200000





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LED4 EQU 0x800000





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ALLLEDS EQU LED1 :OR: LED2 :OR: LED3 :OR: LED4





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leds DCD LED1, LED2, LED3, LED4





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    ALIGN





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 AREA    |.text|, CODE, READONLY





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 EXPORT  binasm





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GPIO1BASE  EQU 0x2009C020; GPIO port 1 base address





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GPIOSETOFF EQU 0x18





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GPIOCLROFF EQU 0x1C





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binasm PROC





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    PUSH {R4, LR}





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    ; Load GPIO Port 1 base address in register R1 





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    LDR     R1, =GPIO1BASE





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    LDR     R4, =(leds+12) ; point to the last element of array





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    ;CLEAR LEDS





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    MOV   R2, #ALLLEDS





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    STR   R2, [R1,#GPIOCLROFF]





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    MOV R3, #4      ; COUNTER FOR LOOP





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    ADD R0, R0, #1  ; INCREMENT PARAMETER BY 1





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loop





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    LDR  R2, [R4], #-4 ; load value from the address in R4 and decrement it by 4





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    LSRS R0, R0, #1    ; shift R0 right and set carry to the shifted out bit





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    STRCC   R2, [R1,#GPIOCLROFF]  ; if==0, clear LED bit





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    STRCS   R2, [R1,#GPIOSETOFF]  ; if==1, set LED bit    





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    SUBS R3, R3, #1





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    BNE loop





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    POP {R4, PC}





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    ENDP





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    ALIGN





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    END