/*-
 * Copyright (c) 2003, 2004 Lev Walkin <vlm@lionet.info>. All rights reserved.
 * Redistribution and modifications are permitted subject to BSD license.
 */
#ifndef	_BER_TLV_TAG_H_
#define	_BER_TLV_TAG_H_

#ifdef __cplusplus
extern "C" {
#endif

	enum asn_tag_class {
		ASN_TAG_CLASS_UNIVERSAL		= 0,	/* 0b00 */
		   ASN_TAG_CLASS_APPLICATION	= 1,	/* 0b01 */
		     ASN_TAG_CLASS_CONTEXT		= 2,	/* 0b10 */
		          ASN_TAG_CLASS_PRIVATE		= 3	/* 0b11 */
	};
	typedef unsigned ber_tlv_tag_t;	/* BER TAG from Tag-Length-Value */

	/*
	 * Tag class is encoded together with tag value for optimization purposes.
	 */
#define	BER_TAG_CLASS(tag)	((tag) & 0x3)
#define	BER_TAG_VALUE(tag)	((tag) >> 2)
#define	BER_TLV_CONSTRUCTED(tagptr)	(((*(const uint8_t *)tagptr)&0x20)?1:0)

#define	BER_TAGS_EQUAL(tag1, tag2)	((tag1) == (tag2))

	/*
	 * Several functions for printing the TAG in the canonical form
	 * (i.e. "[PRIVATE 0]").
	 * Return values correspond to their libc counterparts (if any).
	 */
	ssize_t ber_tlv_tag_snprint(ber_tlv_tag_t tag, char *buf, size_t buflen);
	ssize_t ber_tlv_tag_fwrite(ber_tlv_tag_t tag, FILE *);
	char *ber_tlv_tag_string(ber_tlv_tag_t tag);


	/*
	 * This function tries to fetch the tag from the input stream.
	 * RETURN VALUES:
	 * 	 0:	More data expected than bufptr contains.
	 * 	-1:	Fatal error deciphering tag.
	 *	>0:	Number of bytes used from bufptr. tag_r will contain the tag.
	 */
	ssize_t ber_fetch_tag(const void *bufptr, size_t size, ber_tlv_tag_t *tag_r);

	/*
	 * This function serializes the tag (T from TLV) in BER format.
	 * It always returns number of bytes necessary to represent the tag,
	 * it is a caller's responsibility to check the return value
	 * against the supplied buffer's size.
	 */
	size_t ber_tlv_tag_serialize(ber_tlv_tag_t tag, void *bufptr, size_t size);

#ifdef __cplusplus
}
#endif

#endif	/* _BER_TLV_TAG_H_ */
