(16 bit NASM bare bones)
I use int 1Ah to get time and date, however the time functions seems to have stopped working for some reason.
My time function:
;I/O: BX = string location
get_time:
pusha
mov di, bx
clc ;anti bios-bug team
mov ah, 2 ;BIOS time > bcd
int 1Ah
jnc .read
clc
mov ah, 2
int 1Ah
.read:
mov al, ch ;hours > integer
call bcd_to_int
mov dx, ax ;save
mov al, ch ;hour
shr al, 4 ;higher bcd > lower
and ch, 0Fh ;1`s
test byte [fmt_12_24], 0FFh
jz .twelve_hr
call .add_digit
mov al, ch
call .add_digit
jmp short .minutes
.twelve_hr:
cmp dx, 0
je .midnight
cmp dx, 10
jl .twelve_st1
cmp dx, 12
jle .twelve_st2
mov ax, dx
sub ax, 12
mov bl, 10
div bl
mov ch, ah
cmp al, 0 ;1-9 PM
je .twelve_st1
jmp short .twelve_st2 ;10-11 PM
.midnight:
mov al, 1
mov ch, 2
.twelve_st2:
call .add_digit ;modified bcd
.twelve_st1:
mov al, ch
call .add_digit
mov al, ':'
stosb
.minutes:
mov al, cl ;minute
shr al, 4 ;higher bcd > lower
and cl, 0Fh ;1`s
call .add_digit
mov al, cl
call .add_digit
mov al, ' '
stosb
mov si, .hours_format ;assume 24 hour format
test byte [fmt_12_24], 0FFh
jnz .copy
mov si, .pm_format ;pm?
cmp dx, 12 ;test it!
jg .copy
mov si, .am_format ;no? am!
.copy:
lodsb
stosb
cmp al, 0
jne .copy
popa
ret
.add_digit:
add al, '0' ;into ASCII
stosb ;string into buffer
ret
.hours_format db 'hours',0
.am_format db 'AM',0
.pm_format db 'PM',0
However my date function still works so Im guessing it isnt to do with the interrupt itself:
;I/O: BX = string
get_date:
pusha
mov di, bx
clc ;anti-bug
mov ah, 4 ;data from BIOS in BCD
int 1Ah
jnc .fmt1_day
clc
mov ah, 4 ;BIOS updating
int 1Ah
.fmt1_day:
mov ah, dl ;dd
call .add_2digits
mov al, '/'
stosb ;d/m seperator
.fmt1_month:
mov ah, dh ;mm
call .add_2digits
mov al, '/'
stosb
.fmt1_century:
mov ah, ch ;??00
call .add_2digits
.fmt1_year:
mov ah, cl ;00??
call .add_2digits
mov al, 0
stosb
popa
ret
.add_2digits:
mov al, ah ;AH to 2 ASCII dig
shr al, 4
call .add_digit
mov al, ah
and al, 0Fh
call .add_digit
ret
.add_digit:
add al, '0'
stosb
ret
How do I fix the time function?
It will either: leak a bit of the memory and crash or just crash (crash as in stop, behaves like jmp $)
EDIT:
I have added a password function to my OS, after I implemented it the get_time function stopped working.
If I do not enter the password and fall back to my terminal, and then use the time function it DOES work, does this have to do with memory leaks/overflows?
EDIT 2: It also seems to depend on the length of the password, if its 1 char then it doesnt "influence" the time function but if its longer the function stops working.
EDIT 3: After debugging a bit the code seems to get stuck at the call bcd_to_int, it does not reach it nor does it return. The bcd_to_int function itself does work however
