/* Copyright (C) 2006-2010 Artifex Software, Inc.
   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied, modified
   or distributed except as expressly authorized under the terms of that
   license.  Refer to licensing information at http://www.artifex.com/
   or contact Artifex Software, Inc.,  7 Mt. Lassen  Drive - Suite A-134,
   San Rafael, CA  94903, U.S.A., +1(415)492-9861, for further information.
*/

/* XPS interpreter - unicode text functions */

#include "ghostxps.h"

/*
 * http://tools.ietf.org/html/rfc3629
 */

int
xps_utf8_to_ucs(int *p, const char *ss, int n)
{
    unsigned char *s = (unsigned char *)ss;

    if (s == NULL)
        goto bad;

    if ((s[0] & 0x80) == 0)
    {
        *p = (s[0] & 0x7f);
        return 1;
    }

    if ((s[0] & 0xe0) == 0xc0)
    {
        if (n < 2 || s[1] < 0x80)
            goto bad;
        *p = (s[0] & 0x1f) << 6;
        *p |= (s[1] & 0x3f);
        return 2;
    }

    if ((s[0] & 0xf0) == 0xe0)
    {
        if (n < 3 || s[1] < 0x80 || s[2] < 0x80)
            goto bad;
        *p = (s[0] & 0x0f) << 12;
        *p |= (s[1] & 0x3f) << 6;
        *p |= (s[2] & 0x3f);
        return 3;
    }

    if ((s[0] & 0xf8) == 0xf0)
    {
        if (n < 4 || s[1] < 0x80 || s[2] < 0x80 || s[3] < 0x80)
            goto bad;
        *p = (s[0] & 0x07) << 18;
        *p |= (s[1] & 0x3f) << 12;
        *p |= (s[2] & 0x3f) << 6;
        *p |= (s[3] & 0x3f);
        return 4;
    }

bad:
    *p = 0x80;
    return 1;
}