source: xtideuniversalbios/trunk/Assembly_Library/Src/String/Char.asm

; Project name  :   Assembly Library
; Description   :   Functions for handling characters.

;
; XTIDE Universal BIOS and Associated Tools
; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team.
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 2 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.
; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
;

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; This macro can only be used within this source file!!!
; IS_BETWEEN_IMMEDIATES
;   Parameters:
;       %1:     Value to check
;       %2:     First accepted value in range
;       %3:     Last accepted value in range
;   Returns:
;       CF:     Set if character in range
;               (Jumps to Char_CharIsNotValid if before range)
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%macro IS_BETWEEN_IMMEDIATES 3
    cmp     %1, %2
    jb      SHORT Char_CharIsNotValid
    cmp     %1, (%3)+1              ; Set CF if %1 is lesser
%endmacro


;--------------------------------------------------------------------
; Char_IsLowerCaseLetterInAL
;   Parameters:
;       AL:     Character to check
;   Returns:
;       CF:     Set if character is lower case letter ('a'...'z')
;               Cleared if character is not lower case letter
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%ifdef EXCLUDE_FROM_XUB
    %ifndef MODULE_HOTKEYS
        %define EXCLUDE
    %endif
%endif

%ifndef EXCLUDE OR EXCLUDE_FROM_BIOSDRVS
ALIGN STRING_JUMP_ALIGN
Char_IsLowerCaseLetterInAL:
    IS_BETWEEN_IMMEDIATES al, 'a', 'z'
    ret
%endif
%undef EXCLUDE


;--------------------------------------------------------------------
; Char_IsUpperCaseLetterInAL
;   Parameters:
;       AL:     Character to check
;   Returns:
;       CF:     Set if character is upper case letter ('A'...'Z')
;               Cleared if character is not upper case letter
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%ifndef EXCLUDE_FROM_XUB OR EXCLUDE_FROM_BIOSDRVS
ALIGN STRING_JUMP_ALIGN
Char_IsUpperCaseLetterInAL:
    IS_BETWEEN_IMMEDIATES al, 'A', 'Z'
    ret
%endif


;--------------------------------------------------------------------
; Char_IsHexadecimalDigitInAL
;   Parameters:
;       AL:     Character to check
;   Returns:
;       AL:     Character converted to lower case
;       CF:     Set if character is decimal digit ('0'...'F')
;               Cleared if character is not decimal digit
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%ifndef EXCLUDE_FROM_XUB OR EXCLUDE_FROM_BIOSDRVS
ALIGN STRING_JUMP_ALIGN
Char_IsHexadecimalDigitInAL:
    call    Char_IsDecimalDigitInAL
    jc      SHORT Char_CharIsValid
    call    Char_ALtoLowerCaseLetter
    IS_BETWEEN_IMMEDIATES al, 'a', 'f'
    ret
%endif


;--------------------------------------------------------------------
; Char_IsDecimalDigitInAL
;   Parameters:
;       AL:     Character to check
;   Returns:
;       CF:     Set if character is decimal digit ('0'...'9')
;               Cleared if character is not decimal digit
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%ifndef MODULE_STRINGS_COMPRESSED
ALIGN STRING_JUMP_ALIGN
Char_IsDecimalDigitInAL:
    IS_BETWEEN_IMMEDIATES al, '0', '9'
    ret
%endif


;--------------------------------------------------------------------
; Char_ConvertIntegerToALfromDigitInALwithBaseInBX
;   Parameters:
;       AL:     Character to convert
;       BX:     Numeric base (10 or 16)
;   Returns:
;       AL:     Character converted to integer
;       CF:     Set if character was valid
;               Cleared if character was invalid
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%ifndef EXCLUDE_FROM_XUB OR EXCLUDE_FROM_BIOSDRVS
ALIGN STRING_JUMP_ALIGN
Char_ConvertIntegerToALfromDigitInALwithBaseInBX:
    push    dx
    call    Char_GetFilterFunctionToDXforNumericBaseInBX
    call    dx                      ; Converts to lower case
    pop     dx
    jnc     SHORT Char_CharIsNotValid

    cmp     al, '9'                 ; Decimal digit
    jbe     SHORT .ConvertToDecimalDigit
    sub     al, 'a'-'0'-10          ; Convert to hexadecimal integer
ALIGN STRING_JUMP_ALIGN
.ConvertToDecimalDigit:
    sub     al, '0'                 ; Convert to decimal integer
    ; Fall to Char_CharIsValid
%endif


;--------------------------------------------------------------------
; Char_CharIsValid
; Char_CharIsNotValid
;   Parameters:
;       Nothing
;   Returns:
;       CF:     Set for Char_CharIsValid
;               Cleared for Char_CharIsNotValid
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%ifndef EXCLUDE_FROM_XUB OR EXCLUDE_FROM_BIOSDRVS
ALIGN STRING_JUMP_ALIGN
Char_CharIsValid:
    stc
    ret
%endif


%ifdef EXCLUDE_FROM_XUB
    %ifndef MODULE_HOTKEYS
        %define EXCLUDE
    %endif
    %ifndef MODULE_STRINGS_COMPRESSED
        %undef EXCLUDE
    %endif
%endif

%ifndef EXCLUDE
ALIGN STRING_JUMP_ALIGN
Char_CharIsNotValid:
    clc
    ret
%endif
%undef EXCLUDE


;--------------------------------------------------------------------
; Char_ALtoLowerCaseLetter
;   Parameters:
;       AL:     Character to convert
;   Returns:
;       AL:     Character with possible conversion
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%ifndef EXCLUDE_FROM_XUB OR EXCLUDE_FROM_BIOSDRVS
ALIGN STRING_JUMP_ALIGN
Char_ALtoLowerCaseLetter:
    call    Char_IsUpperCaseLetterInAL  ; Is upper case character?
    jmp     SHORT Char_ALtoUpperCaseLetter.CheckCF
%endif


;--------------------------------------------------------------------
; Char_ALtoUpperCaseLetter
;   Parameters:
;       AL:     Character to convert
;   Returns:
;       AL:     Character with possible conversion
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%ifndef EXCLUDE_FROM_XUB OR EXCLUDE_FROM_BIOSDRVS
ALIGN STRING_JUMP_ALIGN
Char_ALtoUpperCaseLetter:
    call    Char_IsLowerCaseLetterInAL  ; Is lower case character?
.CheckCF:
    jnc     SHORT Char_ChangeCaseInAL.Return
    ; Fall to Char_ChangeCaseInAL
%endif


;--------------------------------------------------------------------
; Char_ChangeCaseInAL
;   Parameters:
;       AL:     Character to convert (must be A-Z or a-z)
;   Returns:
;       AL:     Character converted
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%ifndef EXCLUDE_FROM_XUB OR EXCLUDE_FROM_BIOSDRVS
Char_ChangeCaseInAL:
    xor     al, 32
.Return:
    ret
%endif


;--------------------------------------------------------------------
; Char_GetFilterFunctionToDXforNumericBaseInBX
;   Parameters
;       BX:     Numeric base (10 or 16)
;   Returns:
;       CS:DX:  Ptr to character filter function
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%ifndef EXCLUDE_FROM_XUB OR EXCLUDE_FROM_BIOSDRVS
ALIGN STRING_JUMP_ALIGN
Char_GetFilterFunctionToDXforNumericBaseInBX:
    mov     dx, Char_IsDecimalDigitInAL
    cmp     bl, 10
    je      SHORT .Return
    mov     dx, Char_IsHexadecimalDigitInAL
.Return:
    ret
%endif