BIOS - KEYBOARD(Check/Get Keystroke, Get Shift Flags)

/*******************************************/
KEYBOARD - GET KEYSTROKE
Input:
AH = 00h
INT 16h
Return: 
AH = BIOS scan code
AL = ASCII character
/*******************************************/
KEYBOARD - CHECK FOR KEYSTROKE
Input:
AH = 01h
INT 16h
Return: 
ZF set if no keystroke available
ZF clear if keystroke available
   AH = BIOS scan code
   AL = ASCII character
/*******************************************/
KEYBOARD - GET SHIFT FLAGS
Input:
AH = 02h
INT 16h
Return:
AL = shift flags

Bitfields for keyboard shift flags:
Bit(s) Description
 7   Insert active
 6 CapsLock active
 5 NumLock active
 4 ScrollLock active
 3 Alt key pressed (either Alt on 101/102-key keyboards)
 2 Ctrl key pressed (either Ctrl on 101/102-key keyboards)
 1 left shift key pressed
 0 right shift key pressed
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Example:

typedef struct _Key_Info{
u8 ScanCode;
u8 ASCiiCode;
u8 StatusCode;
u8 Reserved;
} Key_Info;

u8 wait_for_input(Key_Info *pKeyInfo)
{
u8 Scan = 0;
u8 ASCii = 0;
u8 Status = 0;
u8 key_press = 0;
__asm {
pusha
mov bl, 0x00

clearbuf:
mov ah, 0x01
int 16h
jz exit1

mov ah, 0x00
int 16h
mov Scan, ah
mov ASCii, al

mov ah, 0x02
int 16h
mov Status, al
mov bl, 0x01
jmp clearbuf

exit1:
mov key_press, bl
popa
}
pKeyInfo->ScanCode = Scan;
pKeyInfo->ASCiiCode = ASCii;
pKeyInfo->StatusCode = Status;
return key_press;
}