/*********************************************************************

    unicode.c

    Unicode related functions

****************************************************************************

    Copyright Aaron Giles
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are 
    met:

        * Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.
        * Redistributions in binary form must reproduce the above copyright
          notice, this list of conditions and the following disclaimer in 
          the documentation and/or other materials provided with the 
          distribution.
        * Neither the name 'MAME' nor the names of its contributors may be 
          used to endorse or promote products derived from this software 
          without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY AARON GILES ''AS IS'' AND ANY EXPRESS OR 
    IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    DISCLAIMED. IN NO EVENT SHALL AARON GILES BE LIABLE FOR ANY DIRECT, 
    INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 
    SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
    HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
    STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
    IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
    POSSIBILITY OF SUCH DAMAGE.

***************************************************************************/

#include "unicode.h"


/*-------------------------------------------------
    uchar_isvalid - return true if a given
    character is a legitimate unicode character
-------------------------------------------------*/

int uchar_isvalid(unicode_char uchar)
{
	return (uchar < 0x110000) && !((uchar >= 0xd800) && (uchar <= 0xdfff));
}


/*-------------------------------------------------
    uchar_from_utf8 - convert a UTF-8 sequence
    into a unicode character
-------------------------------------------------*/

int uchar_from_utf8(unicode_char *uchar, const char *utf8char, size_t count)
{
	unicode_char c, minchar;
	int auxlen, i;
	char auxchar;

	/* validate parameters */
	if (utf8char == NULL || count == 0)
		return 0;

	/* start with the first byte */
	c = (unsigned char) *utf8char;
	count--;
	utf8char++;

	/* based on that, determine how many additional bytes we need */
	if (c < 0x80)
	{
		/* unicode char 0x00000000 - 0x0000007F */
		c &= 0x7f;
		auxlen = 0;
		minchar = 0x00000000;
	}
	else if (c >= 0xc0 && c < 0xe0)
	{
		/* unicode char 0x00000080 - 0x000007FF */
		c &= 0x1f;
		auxlen = 1;
		minchar = 0x00000080;
	}
	else if (c >= 0xe0 && c < 0xf0)
	{
		/* unicode char 0x00000800 - 0x0000FFFF */
		c &= 0x0f;
		auxlen = 2;
		minchar = 0x00000800;
	}
	else if (c >= 0xf0 && c < 0xf8)
	{
		/* unicode char 0x00010000 - 0x001FFFFF */
		c &= 0x07;
		auxlen = 3;
		minchar = 0x00010000;
	}
	else if (c >= 0xf8 && c < 0xfc)
	{
		/* unicode char 0x00200000 - 0x03FFFFFF */
		c &= 0x03;
		auxlen = 4;
		minchar = 0x00200000;
	}
	else if (c >= 0xfc && c < 0xfe)
	{
		/* unicode char 0x04000000 - 0x7FFFFFFF */
		c &= 0x01;
		auxlen = 5;
		minchar = 0x04000000;
	}
	else
	{
		/* invalid */
		return -1;
	}

	/* exceeds the count? */
	if (auxlen > count)
		return -1;

	/* we now know how long the char is, now compute it */
	for (i = 0; i < auxlen; i++)
	{
		auxchar = utf8char[i];

		/* all auxillary chars must be between 0x80-0xbf */
		if ((auxchar & 0xc0) != 0x80)
			return -1;

		c = c << 6;
		c |= auxchar & 0x3f;
	}

	/* make sure that this char is above the minimum */
	if (c < minchar)
		return -1;

	*uchar = c;
	return auxlen + 1;
}


/*-------------------------------------------------
    uchar_from_utf16 - convert a UTF-16 sequence
    into a unicode character
-------------------------------------------------*/

int uchar_from_utf16(unicode_char *uchar, const utf16_char *utf16char, size_t count)
{
	int rc = -1;

	/* validate parameters */
	if (utf16char == NULL || count == 0)
		return 0;

	/* handle the two-byte case */
	if (utf16char[0] >= 0xd800 && utf16char[0] <= 0xdbff)
	{
		if (count > 1 && utf16char[1] >= 0xdc00 && utf16char[1] <= 0xdfff)
		{
			*uchar = 0x10000 + ((utf16char[0] & 0x3ff) * 0x400) + (utf16char[1] & 0x3ff);
			rc = 2;
		}
	}

	/* handle the one-byte case */
	else if (utf16char[0] < 0xdc00 || utf16char[0] > 0xdfff)
	{
		*uchar = utf16char[0];
		rc = 1;
	}

	return rc;
}


/*-------------------------------------------------
    uchar_from_utf16f - convert a UTF-16 sequence
    into a unicode character from a flipped
    byte order
-------------------------------------------------*/

int uchar_from_utf16f(unicode_char *uchar, const utf16_char *utf16char, size_t count)
{
	utf16_char buf[2] = {0};
	if (count > 0)
		buf[0] = FLIPENDIAN_INT16(utf16char[0]);
	if (count > 1)
		buf[1] = FLIPENDIAN_INT16(utf16char[1]);
	return uchar_from_utf16(uchar, buf, count);
}


/*-------------------------------------------------
    utf8_from_uchar - convert a unicode character
    into a UTF-8 sequence
-------------------------------------------------*/

int utf8_from_uchar(char *utf8string, size_t count, unicode_char uchar)
{
	int rc = 0;

	/* error on invalid characters */
	if (!uchar_isvalid(uchar))
		return -1;

	/* based on the value, output the appropriate number of bytes */
	if (uchar < 0x80)
	{
		/* unicode char 0x00000000 - 0x0000007F */
		if (count < 1)
			return -1;
		utf8string[rc++] = (char) uchar;
	}
	else if (uchar < 0x800)
	{
		/* unicode char 0x00000080 - 0x000007FF */
		if (count < 2)
			return -1;
		utf8string[rc++] = ((char) (uchar >> 6)) | 0xC0;
		utf8string[rc++] = ((char) ((uchar >> 0) & 0x3F)) | 0x80;
	}
	else if (uchar < 0x10000)
	{
		/* unicode char 0x00000800 - 0x0000FFFF */
		if (count < 3)
			return -1;
		utf8string[rc++] = ((char) (uchar >> 12)) | 0xE0;
		utf8string[rc++] = ((char) ((uchar >> 6) & 0x3F)) | 0x80;
		utf8string[rc++] = ((char) ((uchar >> 0) & 0x3F)) | 0x80;
	}
	else if (uchar < 0x00200000)
	{
		/* unicode char 0x00010000 - 0x001FFFFF */
		if (count < 4)
			return -1;
		utf8string[rc++] = ((char) (uchar >> 18)) | 0xF0;
		utf8string[rc++] = ((char) ((uchar >> 12) & 0x3F)) | 0x80;
		utf8string[rc++] = ((char) ((uchar >> 6) & 0x3F)) | 0x80;
		utf8string[rc++] = ((char) ((uchar >> 0) & 0x3F)) | 0x80;
	}
	else if (uchar < 0x04000000)
	{
		/* unicode char 0x00200000 - 0x03FFFFFF */
		if (count < 5)
			return -1;
		utf8string[rc++] = ((char) (uchar >> 24)) | 0xF8;
		utf8string[rc++] = ((char) ((uchar >> 18) & 0x3F)) | 0x80;
		utf8string[rc++] = ((char) ((uchar >> 12) & 0x3F)) | 0x80;
		utf8string[rc++] = ((char) ((uchar >> 6) & 0x3F)) | 0x80;
		utf8string[rc++] = ((char) ((uchar >> 0) & 0x3F)) | 0x80;
	}
	else if (uchar < 0x80000000)
	{
		/* unicode char 0x04000000 - 0x7FFFFFFF */
		if (count < 6)
			return -1;
		utf8string[rc++] = ((char) (uchar >> 30)) | 0xFC;
		utf8string[rc++] = ((char) ((uchar >> 24) & 0x3F)) | 0x80;
		utf8string[rc++] = ((char) ((uchar >> 18) & 0x3F)) | 0x80;
		utf8string[rc++] = ((char) ((uchar >> 12) & 0x3F)) | 0x80;
		utf8string[rc++] = ((char) ((uchar >> 6) & 0x3F)) | 0x80;
		utf8string[rc++] = ((char) ((uchar >> 0) & 0x3F)) | 0x80;
	}
	else
		rc = -1;

	return rc;
}


/*-------------------------------------------------
    utf16_from_uchar - convert a unicode character
    into a UTF-16 sequence
-------------------------------------------------*/

int utf16_from_uchar(utf16_char *utf16string, size_t count, unicode_char uchar)
{
	int rc;

	/* error on invalid characters */
	if (!uchar_isvalid(uchar))
		return -1;

	/* single word case */
	if (uchar < 0x10000)
	{
		if (count < 1)
			return -1;
		utf16string[0] = (utf16_char) uchar;
		rc = 1;
	}

	/* double word case */
	else if (uchar < 0x100000)
	{
		if (count < 2)
			return -1;
		utf16string[0] = ((uchar >> 10) & 0x03ff) | 0xd800;
		utf16string[1] = ((uchar >>  0) & 0x03ff) | 0xdc00;
		rc = 2;
	}
	else
		return -1;
	return rc;
}


/*-------------------------------------------------
    utf16_from_uchar - convert a unicode character
    into a UTF-16 sequence with flipped endianness
-------------------------------------------------*/

int utf16f_from_uchar(utf16_char *utf16string, size_t count, unicode_char uchar)
{
	int rc;
	utf16_char buf[2] = { 0, 0 };

	rc = utf16_from_uchar(buf, count, uchar);

	if (rc >= 1)
		utf16string[0] = FLIPENDIAN_INT16(buf[0]);
	if (rc >= 2)
		utf16string[1] = FLIPENDIAN_INT16(buf[1]);
	return rc;
}


/*-------------------------------------------------
    utf8_previous_char - return a pointer to the
    previous character in a string
-------------------------------------------------*/

const char *utf8_previous_char(const char *utf8string)
{
	while ((*--utf8string & 0xc0) == 0x80)
		;
	return utf8string;
}


/*-------------------------------------------------
    utf8_is_valid_string - return true if the
    given string is a properly formed sequence of
    UTF-8 characters
-------------------------------------------------*/

int utf8_is_valid_string(const char *utf8string)
{
	int remaining_length = strlen(utf8string);

	while (*utf8string != 0)
	{
		unicode_char uchar = 0;
		int charlen;

		/* extract the current character and verify it */
		charlen = uchar_from_utf8(&uchar, utf8string, remaining_length);
		if (charlen <= 0 || uchar == 0 || !uchar_isvalid(uchar))
			return FALSE;

		/* advance */
		utf8string += charlen;
		remaining_length -= charlen;
	}

	return TRUE;
}
