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

    imageutl.h

    Image related utilities

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

    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 <ctype.h>
#include "imageutl.h"

int compute_log2(int val)
{
	int count = 0;

	while(val > 1)
	{
		if (val & 1)
			return -1;
		val /= 2;
		count++;
	}
	return (val == 0) ? -1 : count;
}

/*
   Compute CCITT CRC-16 using the correct bit order for floppy disks.
   CRC code courtesy of Tim Mann.
*/

/* Accelerator table to compute the CRC eight bits at a time */
static const unsigned short ccitt_crc16_table[256] =
{
	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
	0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
	0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
	0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
	0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
	0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
	0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
	0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
	0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
	0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
	0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
	0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
	0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
	0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
	0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
	0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
	0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
	0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
	0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
	0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
	0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
	0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
	0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
	0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
	0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
	0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
	0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
	0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
	0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
	0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
	0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
	0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
};

unsigned short ccitt_crc16(unsigned short crc, const unsigned char *buffer, size_t buffer_len)
{
	size_t i;
	for (i = 0; i < buffer_len; i++)
		crc = (crc << 8) ^ ccitt_crc16_table[(crc >> 8) ^ buffer[i]];
	return crc;
}

unsigned short ccitt_crc16_one( unsigned short crc, const unsigned char data )
{
    return (crc << 8) ^ ccitt_crc16_table[(crc >> 8) ^ data];
}


/*-------------------------------------------------
    is_delim - returns whether c is a comma or \0
-------------------------------------------------*/

static int is_delim(char c)
{
	return (c == '\0') || (c == ',');
}



/*-------------------------------------------------
    image_internal_find_extension - find an extension in
    an extension list
-------------------------------------------------*/

static int image_internal_find_extension(const char *extension_list, const char *target_extension)
{
	/* this version allows target_extension to be delimited with a comma */
	int pos = 0;
	int i;

	while(extension_list[pos] != '\0')
	{
		/* compare a file extension */
		i = 0;
		while(!is_delim(extension_list[pos + i])
			&& !is_delim(target_extension[i])
			&& (tolower(extension_list[pos + i]) == tolower(target_extension[i])))
		{
			i++;
		}

		/* check to see if it was found */
		if (is_delim(extension_list[pos + i]) && is_delim(target_extension[i]))
			return TRUE;

		/* move to next position in the buffer */
		pos += i;
		while(!is_delim(extension_list[pos]))
			pos++;
		while(extension_list[pos] == ',')
			pos++;
	}

	/* not found */
	return FALSE;
}



/*-------------------------------------------------
    image_find_extension - find an extension in an extension
    list
-------------------------------------------------*/

int image_find_extension(const char *extension_list, const char *target_extension)
{
	/* the internal function allows something that we do not */
	if (strchr(target_extension, ','))
		return FALSE;

	/* special case to allow ext to be in the form '.EXT' */
	if (*target_extension == '.')
		target_extension++;

	/* do the actual work */
	return image_internal_find_extension(extension_list, target_extension);
}



/*-------------------------------------------------
    image_specify_extension - merge a comma-delimited
    list of file extensions onto an existing list
-------------------------------------------------*/

void image_specify_extension(char *buffer, size_t buffer_len, const char *extension)
{
	int extension_pos = 0;
	int len;
	int found;

	/* determine the length of the buffer */
	len = strlen(buffer);

	/* be aware that extension can be NULL */
	if (extension != NULL)
	{
		while(extension[extension_pos] != '\0')
		{
			/* try to find the file extension */
			found = image_internal_find_extension(buffer, &extension[extension_pos]);

			/* append a delimiter if we have to */
			if (!found && (len > 0))
				len += snprintf(&buffer[len], buffer_len - len, ",");

			/* move to the next extension, appending the extension if not found */
			while(!is_delim(extension[extension_pos]))
			{
				if (!found)
					len += snprintf(&buffer[len], buffer_len - len, "%c", extension[extension_pos]);
				extension_pos++;
			}
			while(extension[extension_pos] == ',')
				extension_pos++;
		}
	}
}

