c04-03.asm

[org 0x0100]

jmp start

multiplicand:   dw 0xC8    ; 200  =   0b 11001000
multiplier:     db 0x32    ; 50   =   0b 00110010 
result:         dw 0       ; should be 10,000 = 0x2710 

start:

mov  cl, 8
mov  dl, [multiplier]


checkbit: 
    shr  dl, 1
    jnc  skip

        mov  al, [multiplicand]      ; extended addition 
        add  byte [result], al
        mov  al, [multiplicand + 1]
        adc  byte [result + 1], al 

    skip:
    shl  byte [multiplicand], 1      ; extended shift
    rcl  byte [multiplicand + 1], 1
    
    
    dec  cl
    jnz  checkbit




; exit syscall 
mov  ax, 0x4c00
int  0x21





; helpful bash commands 

; hex to dec
; echo $((16#   F)) 

; dec to hex 
; printf '%x\n'   15 

; bin to hex 
; printf '%x\n' "$((2#   110010))" 

; hex to bin
; printf   '\x32'    | xxd -b | cut -d' ' -f2