147 lines
5.6 KiB
C
147 lines
5.6 KiB
C
/*
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* Copyright 2004 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*/
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/**
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* Determine length of this Standard UTF-8 in Modified UTF-8.
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* Validation is done of the basic UTF encoding rules, returns
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* length (no change) when errors are detected in the UTF encoding.
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*
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* Note: Accepts Modified UTF-8 also, no verification on the
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* correctness of Standard UTF-8 is done. e,g, 0xC080 input is ok.
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*/
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int
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modifiedUtf8LengthOfUtf8(char* string, int length) {
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int new_length;
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int i;
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new_length = 0;
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for ( i = 0 ; i < length ; i++ ) {
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unsigned byte;
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byte = (unsigned char)string[i];
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if ( (byte & 0x80) == 0 ) { /* 1byte encoding */
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new_length++;
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if ( byte == 0 ) {
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new_length++; /* We gain one byte in length on NULL bytes */
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}
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} else if ( (byte & 0xE0) == 0xC0 ) { /* 2byte encoding */
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/* Check encoding of following bytes */
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if ( (i+1) >= length || (string[i+1] & 0xC0) != 0x80 ) {
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break; /* Error condition */
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}
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i++; /* Skip next byte */
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new_length += 2;
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} else if ( (byte & 0xF0) == 0xE0 ) { /* 3byte encoding */
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/* Check encoding of following bytes */
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if ( (i+2) >= length || (string[i+1] & 0xC0) != 0x80
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|| (string[i+2] & 0xC0) != 0x80 ) {
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break; /* Error condition */
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}
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i += 2; /* Skip next two bytes */
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new_length += 3;
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} else if ( (byte & 0xF8) == 0xF0 ) { /* 4byte encoding */
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/* Check encoding of following bytes */
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if ( (i+3) >= length || (string[i+1] & 0xC0) != 0x80
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|| (string[i+2] & 0xC0) != 0x80
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|| (string[i+3] & 0xC0) != 0x80 ) {
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break; /* Error condition */
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}
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i += 3; /* Skip next 3 bytes */
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new_length += 6; /* 4byte encoding turns into 2 3byte ones */
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} else {
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break; /* Error condition */
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}
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}
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if ( i != length ) {
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/* Error in finding new length, return old length so no conversion */
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/* FIXUP: ERROR_MESSAGE? */
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return length;
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}
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return new_length;
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}
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/*
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* Convert Standard UTF-8 to Modified UTF-8.
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* Assumes the UTF-8 encoding was validated by modifiedLength() above.
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*
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* Note: Accepts Modified UTF-8 also, no verification on the
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* correctness of Standard UTF-8 is done. e,g, 0xC080 input is ok.
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*/
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void
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convertUtf8ToModifiedUtf8(char *string, int length, char *new_string, int new_length)
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{
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int i;
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int j;
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j = 0;
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for ( i = 0 ; i < length ; i++ ) {
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unsigned byte1;
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byte1 = (unsigned char)string[i];
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/* NULL bytes and bytes starting with 11110xxx are special */
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if ( (byte1 & 0x80) == 0 ) { /* 1byte encoding */
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if ( byte1 == 0 ) {
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/* Bits out: 11000000 10000000 */
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new_string[j++] = (char)0xC0;
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new_string[j++] = (char)0x80;
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} else {
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/* Single byte */
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new_string[j++] = byte1;
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}
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} else if ( (byte1 & 0xE0) == 0xC0 ) { /* 2byte encoding */
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new_string[j++] = byte1;
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new_string[j++] = string[++i];
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} else if ( (byte1 & 0xF0) == 0xE0 ) { /* 3byte encoding */
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new_string[j++] = byte1;
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new_string[j++] = string[++i];
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new_string[j++] = string[++i];
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} else if ( (byte1 & 0xF8) == 0xF0 ) { /* 4byte encoding */
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/* Beginning of 4byte encoding, turn into 2 3byte encodings */
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unsigned byte2, byte3, byte4, u21;
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/* Bits in: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */
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byte2 = (unsigned char)string[++i];
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byte3 = (unsigned char)string[++i];
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byte4 = (unsigned char)string[++i];
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/* Reconstruct full 21bit value */
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u21 = (byte1 & 0x07) << 18;
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u21 += (byte2 & 0x3F) << 12;
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u21 += (byte3 & 0x3F) << 6;
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u21 += (byte4 & 0x3F);
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/* Bits out: 11101101 1010xxxx 10xxxxxx */
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new_string[j++] = (char)0xED;
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new_string[j++] = 0xA0 + (((u21 >> 16) - 1) & 0x0F);
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new_string[j++] = 0x80 + ((u21 >> 10) & 0x3F);
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/* Bits out: 11101101 1011xxxx 10xxxxxx */
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new_string[j++] = (char)0xED;
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new_string[j++] = 0xB0 + ((u21 >> 6) & 0x0F);
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new_string[j++] = byte4;
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}
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}
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new_string[j] = 0;
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}
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