ARM Code: Find whether number is Prime or Not

ARM Assembly Code to find whether the given number is Prime or Not

This code is tested in Keil uVision 4. Developed for ARM LPC2148 by Abhay Kagalkar 

ARM Code :

 AREA Prime_or_Not,code,readonly 
 ENTRY 
 MOV R0,#15               ;Number which you want to test
 CMP R0,#01               ;Comparing with 01
 BEQ PRIME                ;If equal declare directly as prime
 CMP R0,#02               ;Compare with 02
 BEQ PRIME                ;If equal declare directly as prime
 MOV R1,R0                ;Copy test number in R1
 MOV R2,#02               ;Initial divider
UP                     
 BL DIVISION              ;Call for division sub-function
 CMP R8,#00               ;Compare remainder with 0
 BEQ NOTPRIME             ;If equal then its not prime
 ADD R2,R2,#01            ;If not increment divider and check
 CMP R2,R1                ;Compare divider with test number
 BEQ PRIME                ;All possible numbers are done means It's prime
 B UP                     ;If not repeat until end
NOTPRIME 
 LDR R3,=0x11111111       ;Declaring test number is not prime
 B STOP                   ;Jumping to infinite looping
PRIME 
 LDR R3,=0xFFFFFFFF       ;Declaring test number is prime number
STOP B STOP               ;Infinite looping

DIVISION                  ;Function for division operation
 MOV R8,R0                ;Copy of data from main function
 MOV R9,R2                ;Copy of divider from main function
LOOP                     
 SUB R8,R8,R9             ;Successive subtraction for division
 ADD R10,R10,#01          ;Counter for holding the result of division
 CMP R8,R9                ;Compares for non-zero result
 BPL LOOP                 ;Repeats the loop if subtraction is still needed
 MOV PC,LR                ;Return back to main function
 END 

Output Pic :

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