Assembly Language Functions, embaded system, EECE 237

;

; EECE 237 S15

; Lab #2 Demo Code

;

AREA Lab2, CODE, READONLY

;ENTRY

EXPORT binary_disp

EXPORT hex_disp

EXTERN LCD_write

;------------------------------------------------------------------------------------------------

; binary_disp

;

; Displays the binary representation of the 16 bit value passed as a parameter

; on the 2nd row of the LCD screen (using call s C function LCD_write)

;

binary_disp PROC

PUSH {R4-R7} ; Save R5 since we modify it

MOV R5, #15 ; Loop control variable

loop

MOV R0, #1 ; Row = 1 means second row

MOV R1, R5 ; Column

MOV R2, #'0' ; 0 to be written

PUSH {R0-R6, LR}

BL LCD_write ; Write the character to the LCD

POP {R0-R6, LR}

SUBS R5, R5, #1 ; If count < 16, keep writing

BGE loop

POP {R4-R7} ; Restore R5

MOV R0, #42 ; totally fake return value

BX LR ; return

ENDP

;------------------------------------------------------------------------------------------------

; hex_display

;

; Displays the hex representation of the 16 bit value passed as a parameter

; on the 1st row of the LCD screen starting at column 11(using call s C function LCD_write)

;

hex_disp PROC

PUSH {R4-R7} ; Save R5 since we modify it

MOV R5, #4 ; Loop control variable

MOV R0, #0 ; Row = 0 means first row

MOV R1, #11 ; Column

MOV R2, #'A' ; Poor man's ASCII conversion - A..F

hloop

ADD R2, R2, #1

hwrite

PUSH {R0-R6, LR}

BL LCD_write ; Write the character to the LCD

POP {R0-R6, LR}

ADD R1, R1, #1

SUBS R5, R5, #1 ; If count < 5, keep writing

BGE hloop

POP {R4-R7} ; Restore R5

BX LR ; return

ENDP

END