source: xtideuniversalbios/trunk/Assembly_Library/Src/String/String.asm@ 623

; 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

;--------------------------------------------------------------------
; String_ConvertDSSItoLowerCase
;   Parameters:
;       DS:SI:  Ptr to string to convert
;   Returns:
;       CX:     Number of characters processed
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN STRING_JUMP_ALIGN
String_ConvertDSSItoLowerCase:
    push    dx
    push    ax

    mov     dx, StringProcess_ConvertToLowerCase
    call    StringProcess_DSSIwithFunctionInDX

    pop     ax
    pop     dx
    ret


;--------------------------------------------------------------------
; String_ConvertWordToAXfromStringInDSSIwithBaseInBX
;   Parameters:
;       BX:     Numeric base (10 or 16)
;       DS:SI:  Ptr to string to convert
;   Returns:
;       AX:     Word converted from string
;       CX:     Number of characters processed
;       CF:     Cleared if successful
;               Set if error during conversion
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN STRING_JUMP_ALIGN
String_ConvertWordToAXfromStringInDSSIwithBaseInBX:
    push    di
    push    dx

    xor     di, di
    mov     dx, StringProcess_ConvertToWordInDIWithBaseInBX
    call    StringProcess_DSSIwithFunctionInDX
    xchg    ax, di

    pop     dx
    pop     di
    ret


;--------------------------------------------------------------------
; String_CopyDSSItoESDIandGetLengthToCX
;   Parameters:
;       DS:SI:  Ptr to source NULL terminated string
;       ES:DI:  Ptr to destination buffer
;   Returns:
;       CX:     Number of characters copied
;       SI,DI:  Updated by CX characters
;       CF:     Cleared
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN STRING_JUMP_ALIGN
String_CopyDSSItoESDIandGetLengthToCX:
    push    ax

    xor     cx, cx
ALIGN STRING_JUMP_ALIGN
.CopyNextCharacter:
    lodsb                       ; Load from DS:SI to AL
    test    al, al              ; NULL to end string? (Clears CF)
    jz      SHORT PopAXandReturn
    stosb                       ; Store from AL to ES:DI
    inc     cx                  ; Increment number of characters written
    jmp     SHORT .CopyNextCharacter


;--------------------------------------------------------------------
; String_GetLengthFromDSSItoCX
;   Parameters:
;       DS:SI:  Ptr to NULL terminated string
;   Returns:
;       CX:     String length in characters
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN STRING_JUMP_ALIGN
String_GetLengthFromDSSItoCX:
    push    ax
    push    si

    call    Registers_ExchangeDSSIwithESDI
    xor     ax, ax      ; Find NULL
    mov     cx, -1      ; Full segment if necessary
    repne scasb
    mov     cx, di
    call    Registers_ExchangeDSSIwithESDI

    pop     si
    stc
    sbb     cx, si      ; Subtract NULL
PopAXandReturn:
    pop     ax
    ret