Various Algorithms to swap variables in Simplified assembly

arithmetic.asm

; Swap Registers A & B with no tmp

JMP start
 
   ARG1: DB 13 ; Variable
   ARG2: DB 3  ; Variable
 
start:
   MOV A, [ARG1]  ; A = ARG1;
   MOV B, [ARG2]  ; B = ARG2;
   call swap 
   DB 0           ; exit();


swap:             ; swap(A,B)
   SUB A, B       ; a = a - b
   ADD B, A       ; b = a + b
   SUB B, A       ; b = b - a
   RET 

with_tmp.asm

; Swap Registers A & B with tmp

JMP start
 
   ARG1: DB 13 ; Variable
   ARG2: DB 3  ; Variable
 
start:
   MOV A, [ARG1]  ; A = ARG1;
   MOV B, [ARG2]  ; B = ARG2;
   call swap 
   DB 0           ; exit();


swap:             ; swap(A,B)
   MOV C, A
   MOV A, B
   MOV B, C
   RET 

xor.asm

; Swap Registers A & B with XOR

JMP start
 
   ARG1: DB 13 ; Variable
   ARG2: DB 3  ; Variable
 
start:
   MOV A, [ARG1]  ; A = ARG1;
   MOV B, [ARG2]  ; B = ARG2;
   call swap 
   DB 0           ; exit();


swap:             ; swap(A,B)
   XOR A, B       ; a = a ^ b
   XOR A, B       ; a = a ^ b
   XOR B, A       ; b = b ^ a
   XOR B, A       ; b = b ^ b
   RET