wow.c

wow asm

int fact(int n){
  if (n<1) return 1;
  else
  return n*fact(n-1);
}
fact:
  SUB sp,sp,#8      ;Adjust stack for 2 times
  STR lr,[sp,#4]    ;Save return address
  STR r0,[sp,#0]    ;Save argument n
  CMP r0,#1         ;compare n to 1
  BGE L1
  MOV r0,#1         ;if so,return is 1
  ADD sp,sp,#8      ;Pop 2 items form stack
  MOV pc,lr         ;Return to caller
L1:SUB r0,r0,#1     ;else decrement n
  BL  fact          ;Recursive call
  MOV r12,r0        ;Restore original n
  LDR r0,[sp,#0]    ;and return address
  LDR lr,[sp,#4]    ;pop 2 items from stack
  ADD sp,sp,#8      ;
  MUL r0,r0,r12     ;Multiply to get result
  MOV pc,lr         ;and return