source: xtideuniversalbios/trunk/Assembly_Library/Src/Keyboard/Keyboard.asm @ 104

; Project name  :   Assembly Library
; Description   :   Functions for managing keyboard.

BUFFER_SIZE_FOR_WORD_INPUT      EQU     6   ; 5 chars + NULL

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Reads user inputted word.
; Function returns when ENTER or ESC will be pressed.
; 
; Keyboard_ReadUserInputtedWordWhilePrinting
;   Parameters
;       BX:     Numeric base (10 or 16)
;   Returns:
;       AX:     User inputted word
;       ZF:     Set if user cancellation
;   Corrupts registers:
;       DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
Keyboard_ReadUserInputtedWordWhilePrinting:
    push    ds
    push    si
    push    cx

    mov     cx, BUFFER_SIZE_FOR_WORD_INPUT
    call    Memory_ReserveCXbytesFromStackToDSSI

    call    Char_GetFilterFunctionToDXforNumericBaseInBX
    call    Registers_ExchangeDSSIwithESDI
    call    Keyboard_ReadUserInputtedStringToESDIWhilePrinting
    call    Registers_ExchangeDSSIwithESDI  ; Does not modify FLAGS
    jz      SHORT .CancelledByUser

    call    String_ConvertWordToAXfromStringInDSSIwithBaseInBX
.CancelledByUser:
    add     sp, BYTE BUFFER_SIZE_FOR_WORD_INPUT
    test    cx, cx                          ; Set ZF if string length is zero
    pop     cx
    pop     si
    pop     ds
    ret


;--------------------------------------------------------------------
; Reads user inputted string to buffer. Character filter is
; supported to ignore unwanted characters.
; Function returns when ENTER or ESC will be pressed.
; 
; Keyboard_ReadUserInputtedStringToESDIWhilePrinting
;   Parameters:
;       CX:     Buffer size (with NULL)
;       ES:DI:  Ptr to destination buffer
;       CS:DX:  Ptr to character filter function:
;                   Parameters:
;                       AL:     Character inputted by user
;                   Returns:
;                       CF:     Set if character is accepted
;                               Cleared if character is rejected
;                   Corrupts registers:
;                       Nothing
;   Returns:
;       CX:     String length in characters (without NULL)
;       ZF:     Set if user cancellation
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
Keyboard_ReadUserInputtedStringToESDIWhilePrinting:
    push    di
    push    si
    push    bx
    call    .PrepareDisplayContextForKeyboardInput
    jcxz    .ReturnAfterUpdatingZF

    xor     bx, bx                              ; Zero character counter
    dec     cx                                  ; Decrement buffer size for NULL
    cld
ALIGN JUMP_ALIGN
.GetCharacterFromUser:
    call    Keyboard_GetKeystrokeToAXandWaitIfNecessary ; Get ASCII to AL
    call    .ProcessControlCharacter
    jz      SHORT .TerminateStringWithNULL
    jc      SHORT .PlayBellForRejectedCharacter
    call    dx                                  ; Filter character
    jnc     SHORT .PlayBellForRejectedCharacter
    inc     bx                                  ; Increment number of characters stored
    stosb                                       ; Store from AL to ES:DI
    call    Keyboard_PrintInputtedCharacter
    loop    .GetCharacterFromUser
.PlayBellForRejectedCharacter:
    cmp     al, BS                              ; No bell for backspace
    je      SHORT .GetCharacterFromUser
    call    Keyboard_PlayBellForUnwantedKeystroke
    jmp     SHORT .GetCharacterFromUser

.TerminateStringWithNULL:
    stosb                                       ; Terminate string with NULL
    mov     cx, bx                              ; String length now in CX

.ReturnAfterUpdatingZF:
    CALL_DISPLAY_LIBRARY PopDisplayContext
    test    cx, cx                              ; Clear or set ZF
    pop     bx
    pop     si
    pop     di
    ret

;--------------------------------------------------------------------
; .PrepareDisplayContextForKeyboardInput
;   Parameters:
;       Nothing
;   Returns:
;       Nothing (Display context pushed to stack)
;   Corrupts registers:
;       AX, BX, SI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.PrepareDisplayContextForKeyboardInput:
    pop     bx                  ; Pop return address to BX
    mov     si, di

    CALL_DISPLAY_LIBRARY PushDisplayContext
    mov     ax, CURSOR_NORMAL
    CALL_DISPLAY_LIBRARY SetCursorShapeFromAX
    CALL_DISPLAY_LIBRARY SynchronizeDisplayContextToHardware

    mov     di, si
    jmp     bx


;--------------------------------------------------------------------
; .ProcessControlCharacter
;   Parameters:
;       AL:     Character inputted by user
;       CX:     Number of bytes left in buffer
;       BX:     Total number of characters inputted
;       ES:DI:  Ptr where to store next character
;   Returns:
;       AL:     Character inputted by user or NULL if end of input
;       BX:     Cleared if user cancellation
;       ZF:     Set if user has ended or cancelled key input
;       CF:     Set if character is rejected
;   Corrupts registers:
;       AH
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.ProcessControlCharacter:
    cmp     al, CR                              ; ENTER to terminate string?
    je      SHORT .EndCharacterInput
    cmp     al, ESC                             ; Cancel input?
    je      SHORT .CancelCharacterInput
    cmp     al, BS                              ; Backspace?
    je      SHORT .Backspace
    jcxz    .RejectCharacter
    test    al, al                              ; Clear ZF and CF
    ret

.Backspace:
    test    bx, bx                              ; At the beginning?
    jz      SHORT .RejectCharacter
    inc     cx                                  ; Increment bytes left
    dec     bx                                  ; Decrement characters inputted
    dec     di
    call    Keyboard_PrintBackspace
    mov     al, BS                              ; Restore character
.RejectCharacter:
    test    al, al                              ; Clear ZF...
    stc                                         ; ...and set CF
    ret

.CancelCharacterInput:
    xor     bx, bx
.EndCharacterInput:
    xor     al, al                              ; Set ZF and clear CF
    ret


;--------------------------------------------------------------------
; Keyboard_PrintBackspace
;   Parameters:
;       Nothing
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
Keyboard_PrintBackspace:
    mov     al, BS
    call    Keyboard_PrintInputtedCharacter
    mov     al, ' '
    call    Keyboard_PrintInputtedCharacter
    mov     al, BS
    jmp     SHORT Keyboard_PrintInputtedCharacter


;--------------------------------------------------------------------
; Keyboard_PlayBellForUnwantedKeystroke
;   Parameters:
;       Nothing
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
Keyboard_PlayBellForUnwantedKeystroke:
    mov     al, BELL
    ; Fall to Keyboard_PrintInputtedCharacter

;--------------------------------------------------------------------
; Keyboard_PrintInputtedCharacter
;   Parameters:
;       AL:     Character inputted by user
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
Keyboard_PrintInputtedCharacter:
    push    di
    CALL_DISPLAY_LIBRARY PrintCharacterFromAL
    CALL_DISPLAY_LIBRARY SynchronizeDisplayContextToHardware    ; Hardware cursor
    pop     di
    ret


;--------------------------------------------------------------------
; Keyboard_RemoveAllKeystrokesFromBuffer
;   Parameters:
;       Nothing
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
Keyboard_RemoveAllKeystrokesFromBuffer:
    call    Keyboard_GetKeystrokeToAX
    jnz     SHORT Keyboard_RemoveAllKeystrokesFromBuffer
    ret


;--------------------------------------------------------------------
; Keyboard_GetKeystrokeToAX
; Keyboard_GetKeystrokeToAXandLeaveItToBuffer
; Keyboard_GetKeystrokeToAXandWaitIfNecessary
;   Parameters:
;       Nothing
;   Returns:
;       AL:     ASCII character (if keystroke available)
;       AH:     BIOS scan code (if keystroke available)
;       ZF:     Set if no keystroke available
;               Cleared if keystroke available
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
Keyboard_GetKeystrokeToAX:
    call    Keyboard_GetKeystrokeToAXandLeaveItToBuffer
    jnz     SHORT Keyboard_GetKeystrokeToAXandWaitIfNecessary
    ret 
ALIGN JUMP_ALIGN
Keyboard_GetKeystrokeToAXandLeaveItToBuffer:
    mov     ah, CHECK_FOR_KEYSTROKE
    int     BIOS_KEYBOARD_INTERRUPT_16h
    ret
ALIGN JUMP_ALIGN
Keyboard_GetKeystrokeToAXandWaitIfNecessary:
    xor     ah, ah                      ; GET_KEYSTROKE
    int     BIOS_KEYBOARD_INTERRUPT_16h
    test    ax, ax                      ; Clear ZF
    ret