139 lines
3.7 KiB
C
139 lines
3.7 KiB
C
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/*
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* nputf.c - Routines for utf text processing for notepad
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*
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* Copyright (C) 1998-2000 Microsoft Corporation
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*/
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#include "precomp.h"
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/* IsTextUTF8
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*
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* UTF-8 is the encoding of Unicode based on Internet Society RFC2279
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* ( See http://www.cis.ohio-state.edu/htbin/rfc/rfc2279.html )
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*
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* Basicly:
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* 0000 0000-0000 007F - 0xxxxxxx (ascii converts to 1 octet!)
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* 0000 0080-0000 07FF - 110xxxxx 10xxxxxx ( 2 octet format)
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* 0000 0800-0000 FFFF - 1110xxxx 10xxxxxx 10xxxxxx (3 octet format)
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* (this keeps going for 32 bit unicode)
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*
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*
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* Return value: TRUE, if the text is in UTF-8 format.
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* FALSE, if the text is not in UTF-8 format.
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* We will also return FALSE is it is only 7-bit ascii, so the right code page
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* will be used.
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*
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* Actually for 7 bit ascii, it doesn't matter which code page we use, but
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* notepad will remember that it is utf-8 and "save" or "save as" will store
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* the file with a UTF-8 BOM. Not cool.
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*/
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INT IsTextUTF8( LPSTR lpstrInputStream, INT iLen )
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{
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INT i;
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DWORD cOctets; // octets to go in this UTF-8 encoded character
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UCHAR chr;
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BOOL bAllAscii= TRUE;
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cOctets= 0;
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for( i=0; i < iLen; i++ ) {
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chr= *(lpstrInputStream+i);
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if( (chr&0x80) != 0 ) bAllAscii= FALSE;
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if( cOctets == 0 ) {
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//
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// 7 bit ascii after 7 bit ascii is just fine. Handle start of encoding case.
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//
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if( chr >= 0x80 ) {
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//
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// count of the leading 1 bits is the number of characters encoded
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//
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do {
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chr <<= 1;
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cOctets++;
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}
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while( (chr&0x80) != 0 );
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cOctets--; // count includes this character
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if( cOctets == 0 ) return FALSE; // must start with 11xxxxxx
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}
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}
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else {
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// non-leading bytes must start as 10xxxxxx
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if( (chr&0xC0) != 0x80 ) {
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return FALSE;
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}
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cOctets--; // processed another octet in encoding
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}
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}
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//
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// End of text. Check for consistency.
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//
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if( cOctets > 0 ) { // anything left over at the end is an error
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return FALSE;
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}
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if( bAllAscii ) { // Not utf-8 if all ascii. Forces caller to use code pages for conversion
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return FALSE;
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}
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return TRUE;
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}
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/* IsInputTextUnicode
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* Verify if the input stream is in Unicode format.
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*
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* Return value: TRUE, if the text is in Unicode format.
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*
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* 29 June 1998
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*/
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INT IsInputTextUnicode (LPSTR lpstrInputStream, INT iLen)
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{
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INT iResult= ~0; // turn on IS_TEXT_UNICODE_DBCS_LEADBYTE
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BOOL bUnicode;
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// We would like to check the possibility
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// of IS_TEXT_UNICODE_DBCS_LEADBYTE.
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//
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bUnicode= IsTextUnicode( lpstrInputStream, iLen, &iResult);
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if (bUnicode &&
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((iResult & IS_TEXT_UNICODE_STATISTICS) != 0 ) &&
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((iResult & (~IS_TEXT_UNICODE_STATISTICS)) == 0 ) )
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{
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CPINFO cpiInfo;
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CHAR* pch= (CHAR*)lpstrInputStream;
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INT cb;
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//
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// If the result depends only upon statistics, check
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// to see if there is a possibility of DBCS.
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// Only do this check if the ansi code page is DBCS
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//
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GetCPInfo( CP_ACP, &cpiInfo);
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if( cpiInfo.MaxCharSize > 1 )
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{
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for( cb=0; cb<iLen; cb++ )
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{
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if( IsDBCSLeadByte(*pch++) )
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{
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return FALSE;
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}
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}
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}
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}
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return bUnicode;
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}
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