/*
 * Copyright (c) 2005, 2006, 2007 Lev Walkin <vlm@lionet.info>.
 * All rights reserved.
 * Redistribution and modifications are permitted subject to BSD license.
 */
#ifndef	_PER_SUPPORT_H_
#define	_PER_SUPPORT_H_

#include <asn_system.h>		/* Platform-specific types */

#ifdef __cplusplus
extern "C" {
#endif

	/*
	 * Pre-computed PER constraints.
	 */
	typedef struct asn_per_constraint_s {
		enum asn_per_constraint_flags {
			APC_UNCONSTRAINED	= 0x0,	/* No PER visible constraints */
			  APC_SEMI_CONSTRAINED	= 0x1,	/* Constrained at "lb" */
			     APC_CONSTRAINED		= 0x2,	/* Fully constrained */
			        APC_EXTENSIBLE		= 0x4	/* May have extension */
		} flags;
		int  range_bits;		/* Full number of bits in the range */
		int  effective_bits;		/* Effective bits */
		long lower_bound;		/* "lb" value */
		long upper_bound;		/* "ub" value */
	} asn_per_constraint_t;
	typedef struct asn_per_constraints_s {
		asn_per_constraint_t value;
		asn_per_constraint_t size;
		int (*value2code)(unsigned int value);
		int (*code2value)(unsigned int code);
	} asn_per_constraints_t;

	/*
	 * This structure describes a position inside an incoming PER bit stream.
	 */
	typedef struct asn_per_data_s {
		const uint8_t *buffer;  /* Pointer to the octet stream */
		size_t  nboff;   /* Bit offset to the meaningful bit */
		size_t  nbits;   /* Number of bits in the stream */
		size_t  moved;   /* Number of bits moved through this bit stream */
		int (*refill)(struct asn_per_data_s *);
		void *refill_key;
	} asn_per_data_t;

	/*
	 * Extract a small number of bits (<= 31) from the specified PER data pointer.
	 * This function returns -1 if the specified number of bits could not be
	 * extracted due to EOD or other conditions.
	 */
	int32_t per_get_few_bits(asn_per_data_t *per_data, int get_nbits);

	/* Undo the immediately preceeding "get_few_bits" operation */
	void per_get_undo(asn_per_data_t *per_data, int get_nbits);

	/*
	 * Extract a large number of bits from the specified PER data pointer.
	 * This function returns -1 if the specified number of bits could not be
	 * extracted due to EOD or other conditions.
	 */
	int per_get_many_bits(asn_per_data_t *pd, uint8_t *dst, int right_align,
	                      int get_nbits);

	/*
	 * Get the length "n" from the Unaligned PER stream.
	 */
	ssize_t uper_get_length(asn_per_data_t *pd,
	                        int effective_bound_bits,
	                        int *repeat);

	/*
	 * Get the normally small length "n".
	 */
	ssize_t uper_get_nslength(asn_per_data_t *pd);

	/*
	 * Get the normally small non-negative whole number.
	 */
	ssize_t uper_get_nsnnwn(asn_per_data_t *pd);

	/* Non-thread-safe debugging function, don't use it */
	char *per_data_string(asn_per_data_t *pd);

	/*
	 * This structure supports forming PER output.
	 */
	typedef struct asn_per_outp_s {
		uint8_t *buffer;	/* Pointer into the (tmpspace) */
		size_t nboff;		/* Bit offset to the meaningful bit */
		size_t nbits;		/* Number of bits left in (tmpspace) */
		uint8_t tmpspace[32];	/* Preliminary storage to hold data */
		int (*outper)(const void *data, size_t size, void *op_key);
		void *op_key;		/* Key for (outper) data callback */
		size_t flushed_bytes;	/* Bytes already flushed through (outper) */
	} asn_per_outp_t;

	/* Output a small number of bits (<= 31) */
	int per_put_few_bits(asn_per_outp_t *per_data, uint32_t bits, int obits);

	/* Output a large number of bits */
	int per_put_many_bits(asn_per_outp_t *po, const uint8_t *src, int put_nbits);

	/*
	 * Put the length "n" to the Unaligned PER stream.
	 * This function returns the number of units which may be flushed
	 * in the next units saving iteration.
	 */
	ssize_t uper_put_length(asn_per_outp_t *po, size_t whole_length);

	/*
	 * Put the normally small length "n" to the Unaligned PER stream.
	 * Returns 0 or -1.
	 */
	int uper_put_nslength(asn_per_outp_t *po, size_t length);

	/*
	 * Put the normally small non-negative whole number.
	 */
	int uper_put_nsnnwn(asn_per_outp_t *po, int n);

#ifdef __cplusplus
}
#endif

#endif	/* _PER_SUPPORT_H_ */
