/*

 * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

/**

 * Determine length of this Standard UTF-8 in Modified UTF-8.

 *    Validation is done of the basic UTF encoding rules, returns

 *    length (no change) when errors are detected in the UTF encoding.

 *

 *    Note: Accepts Modified UTF-8 also, no verification on the

 *          correctness of Standard UTF-8 is done. e,g, 0xC080 input is ok.

 */

int

modifiedUtf8LengthOfUtf8(char* string, int length) {

    int new_length;

    int i;

    new_length = 0;

    for ( i = 0 ; i < length ; i++ ) {

        unsigned byte;

        byte = (unsigned char)string[i];

        if ( (byte & 0x80) == 0 ) { /* 1byte encoding */

            new_length++;

            if ( byte == 0 ) {

                new_length++; /* We gain one byte in length on NULL bytes */

            }

        } else if ( (byte & 0xE0) == 0xC0 ) { /* 2byte encoding */

            /* Check encoding of following bytes */

            if ( (i+1) >= length || (string[i+1] & 0xC0) != 0x80 ) {

                break; /* Error condition */

            }

            i++; /* Skip next byte */

            new_length += 2;

        } else if ( (byte & 0xF0) == 0xE0 ) { /* 3byte encoding */

            /* Check encoding of following bytes */

            if ( (i+2) >= length || (string[i+1] & 0xC0) != 0x80

                                 || (string[i+2] & 0xC0) != 0x80 ) {

                break; /* Error condition */

            }

            i += 2; /* Skip next two bytes */

            new_length += 3;

        } else if ( (byte & 0xF8) == 0xF0 ) { /* 4byte encoding */

            /* Check encoding of following bytes */

            if ( (i+3) >= length || (string[i+1] & 0xC0) != 0x80

                                 || (string[i+2] & 0xC0) != 0x80

                                 || (string[i+3] & 0xC0) != 0x80 ) {

                break; /* Error condition */

            }

            i += 3; /* Skip next 3 bytes */

            new_length += 6; /* 4byte encoding turns into 2 3byte ones */

        } else {

            break; /* Error condition */

        }

    }

    if ( i != length ) {

        /* Error in finding new length, return old length so no conversion */

        /* FIXUP: ERROR_MESSAGE? */

        return length;

    }

    return new_length;

}

/*

 * Convert Standard UTF-8 to Modified UTF-8.

 *    Assumes the UTF-8 encoding was validated by modifiedLength() above.

 *

 *    Note: Accepts Modified UTF-8 also, no verification on the

 *          correctness of Standard UTF-8 is done. e,g, 0xC080 input is ok.

 */

void

convertUtf8ToModifiedUtf8(char *string, int length, char *new_string, int new_length)

{

    int i;

    int j;

    j = 0;

    for ( i = 0 ; i < length ; i++ ) {

        unsigned byte1;

        byte1 = (unsigned char)string[i];

        /* NULL bytes and bytes starting with 11110xxx are special */

        if ( (byte1 & 0x80) == 0 ) { /* 1byte encoding */

            if ( byte1 == 0 ) {

                /* Bits out: 11000000 10000000 */

                new_string[j++] = (char)0xC0;

                new_string[j++] = (char)0x80;

            } else {

                /* Single byte */

                new_string[j++] = byte1;

            }

        } else if ( (byte1 & 0xE0) == 0xC0 ) { /* 2byte encoding */

            new_string[j++] = byte1;

            new_string[j++] = string[++i];

        } else if ( (byte1 & 0xF0) == 0xE0 ) { /* 3byte encoding */

            new_string[j++] = byte1;

            new_string[j++] = string[++i];

            new_string[j++] = string[++i];

        } else if ( (byte1 & 0xF8) == 0xF0 ) { /* 4byte encoding */

            /* Beginning of 4byte encoding, turn into 2 3byte encodings */

            unsigned byte2, byte3, byte4, u21;

            /* Bits in: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */

            byte2 = (unsigned char)string[++i];

            byte3 = (unsigned char)string[++i];

            byte4 = (unsigned char)string[++i];

            /* Reconstruct full 21bit value */

            u21  = (byte1 & 0x07) << 18;

            u21 += (byte2 & 0x3F) << 12;

            u21 += (byte3 & 0x3F) << 6;

            u21 += (byte4 & 0x3F);

            /* Bits out: 11101101 1010xxxx 10xxxxxx */

            new_string[j++] = (char)0xED;

            new_string[j++] = 0xA0 + (((u21 >> 16) - 1) & 0x0F);

            new_string[j++] = 0x80 + ((u21 >> 10) & 0x3F);

            /* Bits out: 11101101 1011xxxx 10xxxxxx */

            new_string[j++] = (char)0xED;

            new_string[j++] = 0xB0 + ((u21 >>  6) & 0x0F);

            new_string[j++] = byte4;

        }

    }

    new_string[j] = 0;

}