; Calculates (5 + (8 * 15)) * 2 
; Keeps track of overflow errors, 
; and a "times 0" is trapped aswell. 
 
 
mvi d,8H        ; D = 8 
mvi e,EH        ; E = 14 
push d          ; D en E op stack 
call Multiply   ; Do a Multiply!! 
call Add5       ; Add 5 
call Times2     ; Times 2 
 
hlt             ; End of program 
; A is now EA, so 234 
 
 
;=============================== 
;           Subroutines 
 
 
; Gets two bytes from the stack, 
; and leaves the result in the acc 
MULTIPLY:       ; Subroutine Multiplies: A=B*C 
mvi a,0 
pop h           ; POP Program Counter 
pop b 
cmp c 
jnz DoMulti 
push h 
ret 
 
DoMulti: 
add b           ; A = A + B 
jc Overflow     ; Is Overflow? 
dcr c 
jnz DoMulti 
push h          ; Push back Program Counter 
ret 
 
; Adds 5 to the acc and tests for overflow 
ADD5: 
adi 5H          ; A = A + 5 
jc Overflow     ; Is Overflow? 
RET 
 
; Multiplies A with 2, and tests for overflow 
TIMES2: 
add a           ; A = A + A (A*2) 
jc Overflow     ; Is Overflow? 
RET 
 
 
 
; Fake some overflow message, 
; set all registers to FF and break,halt 
OVERFLOW: 
mvi a,FFH 
mvi b,FFH 
mvi c,FFH 
mvi d,FFH 
mvi E,FFH 
mvi H,FFH 
mvi L,FFH 
;BREAK 
HLT