diff options
Diffstat (limited to 'stdio.asm')
| -rw-r--r-- | stdio.asm | 78 |
1 files changed, 54 insertions, 24 deletions
@@ -55,17 +55,17 @@ printh: puthex: + push bp + mov bp, sp + push ax push bx push cx push dx + push di - ; ax is integer to print - ror ah, 4 ; reverse hex value - ror al, 4 - xchg ah, al - - mov cx, 04h ; count (leading zeros) + xor di, di ; local stack counter + mov cx, 02h ; padding count (leading zeros) .divide: mov bx, 10h ; set divisor @@ -75,37 +75,56 @@ puthex: cmp dl, 10 ; don't adjust values less than 10 jl .decimal .alpha: - sub dl, 10 ; (remainder - 10) -> align with ascii (base 10) - add dl, 'A' ; (remainder + 'A') -> ascii offset conversion - jmp .write + sub dl, 10 ; (remainder - 10) -> align with ascii (base 10) + add dl, 'A' ; (remainder + 'A') -> ascii offset conversion + jmp .collect .decimal: - or dl, 30h ; remainder -> ascii - .write: - dec cx - xchg ax, dx ; exchange registers to get ascii value - call putc ; print value - xchg ax, dx ; restore registers + or dl, 30h ; remainder -> ascii - cmp al, 0 ; loop if al != 0 - jne .divide + .collect: + push dx ; push ascii value onto stack + inc di ; increment stack counter - cmp cx, 0 + cmp ax, 0 ; loop if al != 0 jne .divide + cmp di, cx ; only pad zeros if padding count is greater than + ; the number of elements pushed to the stack + jge .write + + mov dx, 30h ; store padding byte (ascii zero) + sub cx, di ; How many zeros will we pad? + .padding: + push dx ; push padding byte + inc di ; increment stack counter + dec cx ; decrement padding counter + jne .padding ; loop until CX == 0 + + .write: + dec di ; decrement stack counter + dec cx ; decrement padding counter + + pop ax ; pop ascii value off stack + call putc ; print value + + cmp di, 0 + jne .write .return: + pop di pop dx pop cx pop bx pop ax + mov sp, bp + pop bp ret - putint: push bp mov bp, sp pusha - mov cx, 05h ; count (+leading zeros) + mov cx, 00h ; count (+leading zeros) mov di, 00h ; inner loop count .divide: mov bx, 0Ah ; set divisor @@ -114,19 +133,28 @@ putint: div bx ; divide by 10 or dl, 30h ; remainder -> ascii - dec cx + ;dec cx inc di ; local stack counter push dx cmp al, 0 ; loop if al != 0 jne .divide - cmp cx, 0 ; no more zeros? - jne .divide + cmp di, cx ; only pad zeros if padding count is greater than + ; the number of elements pushed to the stack + jge .write + + mov dx, 30h ; store padding byte (ascii zero) + sub cx, di ; How many zeros will we pad? + .padding: + push dx ; push padding byte + inc di ; increment stack counter + dec cx ; decrement padding counter + jne .padding ; loop until CX == 0 .write: pop ax ; pop first value of integer - dec di ; decrement our loop counter + dec di ; decrement our stack counter call putc ; write character cmp di, 0 ; done? jne .write @@ -141,6 +169,7 @@ putint: printf: push bp mov bp, sp + pusha mov di, bp ; save base pointer address push di @@ -247,6 +276,7 @@ printf: ; it, we're doomed; we'll roll right off the ; edge into oblivion. pop di + popa mov sp, bp pop bp ret |