102 lines
1.1 KiB
NASM
102 lines
1.1 KiB
NASM
cpu 8086
|
|
org 0x3000
|
|
|
|
xor dx, dx
|
|
|
|
cmp byte [si], 0
|
|
jne htoi
|
|
|
|
mov ah, 2
|
|
mov si, overflow_msg
|
|
int 0x21
|
|
int 0x20
|
|
|
|
htoi:
|
|
lodsb
|
|
|
|
cmp al, 0
|
|
je .end
|
|
|
|
.digit09:
|
|
cmp al, '0'
|
|
jl .notdigit
|
|
|
|
cmp al, '9'
|
|
jg .digitcapital
|
|
|
|
sub al, '0'
|
|
jmp .digit
|
|
|
|
.digitcapital:
|
|
cmp al, 'A'
|
|
jl .notdigit
|
|
|
|
cmp al, 'F'
|
|
jg .digitminuscule
|
|
|
|
sub al, 'A' - 10
|
|
jmp .digit
|
|
|
|
.digitminuscule:
|
|
cmp al, 'a'
|
|
jl .notdigit
|
|
|
|
cmp al, 'f'
|
|
jg .notdigit
|
|
|
|
sub al, 'a' - 10
|
|
jmp .digit
|
|
|
|
.digit:
|
|
xor ah, ah
|
|
|
|
test dx, 0xf000
|
|
jnz .overflow
|
|
|
|
shl dx, 1
|
|
shl dx, 1
|
|
shl dx, 1
|
|
shl dx, 1
|
|
or dx, ax
|
|
|
|
jmp htoi
|
|
|
|
.notdigit:
|
|
mov byte [char_slot], al
|
|
mov si, notdigit_msg
|
|
mov ah, 2
|
|
int 0x21
|
|
int 0x20
|
|
|
|
.overflow:
|
|
mov si, overflow_msg
|
|
mov ah, 2
|
|
int 0x21
|
|
int 0x20
|
|
|
|
.end:
|
|
|
|
mov si, decimalstring + 5
|
|
mov ax, dx
|
|
itoa:
|
|
dec si
|
|
xor dx, dx
|
|
div word [ten]
|
|
add dl, '0'
|
|
mov byte [si], dl
|
|
|
|
test ax, ax
|
|
jnz itoa
|
|
|
|
mov ah, 2
|
|
int 0x21
|
|
int 0x20
|
|
|
|
notdigit_msg db "Not a digit '"
|
|
char_slot db 0, "'", 0
|
|
overflow_msg db "Value must be in range 0 to ffff", 0
|
|
|
|
decimalstring db "xxxxx", 0
|
|
|
|
ten dw 10
|