/* *****************************************************************************
 * core/decode.c -- decode a file.
 * Copyright (C) 2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
 *
 * This file is part of libg1m.
 * libg1m is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 3.0 of the License,
 * or (at your option) any later version.
 *
 * libg1m 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with libg1m; if not, see <http://www.gnu.org/licenses/>.
 * ************************************************************************** */
#include <libg1m/internals.h>

/**
 *	g1m_decode:
 *	Decode a file.
 *
 *	Read the standard header, correct endianness, check magic numbers,
 *	then read subparts according to the G1M type.
 *
 *	@arg	handle			the handle.
 *	@arg	path			the file path.
 *	@arg	buffer			the buffer to read from.
 *	@arg	expected_types	the expected types.
 *	@return					the error code (0 if ok).
 */

int g1m_decode(g1m_t *handle, const char *path, g1m_buffer_t *buffer,
	g1m_type_t expected_types)
{
	/* initialize the handle */
	memset(handle, 0, sizeof(g1m_t));

	/* identify a CAS file */
	unsigned char buf[0x20]; READ(buf, 1)
	if (buf[0] == ':')
		return (g1m_decode_cas(handle, buffer, expected_types));

	/* identify a Casemul file */
	READ(&buf[1], 3)
	if (!memcmp(buf, "CAFS", 4)) {
		handle->platform |= g1m_platflag_be;
	} else if (!memcmp(buf, "ACFS", 4))
		return (g1m_decode_casemul(handle, buffer));

	/* identify a standard header (send a _copy_) */
	READ(&buf[1], 0x1C)
	uint8_t altbuf[0x20]; memcpy(altbuf, buf, 0x20);
	return (g1m_decode_std(handle, path, buffer,
		(struct standard_header*)altbuf, expected_types));
}