libisofs-legacy/libisofs/struct.h

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2006-08-15 20:37:04 +00:00
/* vim: set noet ts=8 sts=8 sw=8 : */
/**
* \file struct.h
* Add functionality similar to the python "struct" module to make it easier
* to read and write .iso structures.
*
* The following conversions are supported:
* B uint8_t, the arg should be (uint8_t*)
* H uint16_t, the arg should be (uint16_t*)
* L uint32_t, the arg should be (uint32_t*)
* S a 7-byte timestamp, the arg should be (time_t*)
* T a 17-byte timestamp, the arg should be (time_t*)
* x ignored field, no arg should be specified
*
* Any of the first 3 conversions may be preceded by a endian specifier:
* < little-endian
* > big-endian
* = both-endian (ie. according to ecma119 7.2.3 or 7.3.3)
*
* Each conversion specifier may also be preceded by a length specifier. For
* example, "<5L" specifies an array of 5 little-endian 32-bit integers. Note
* that "=L" takes 8 bytes while "<L" and ">L" each take 4.
*
* You can use a lower-case conversion specifier instead of an upper-case one
* to signify that the (multi-element) conversion should stop when a zero is
* reached. This is useful for writing out NULL-terminated strings. Note that
* this has no effect when unpacking data from a struct.
*/
#ifndef __ISO_STRUCT
#define __ISO_STRUCT
#include <stdint.h>
/**
* Unpack a struct into its components. The list of components is a list of
* pointers to the variables to write.
*
* For example:
* uint8_t byte1, byte2;
* uint16_t uint;
* iso_struct_unpack("BB=H", data, &byte1, &byte2, &uint);
*
* \return The number of conversions performed, or -1 on error.
*/
int iso_struct_unpack(const char *fmt, const uint8_t *data, ...);
/**
* Write out a struct from its components. The list of components is a list of
* pointers to the variables to write and the buffer to which to write
* is assumed to be large
* enough to take the data.
*
* \return The number of conversions performed, or -1 on error.
*/
int iso_struct_pack(const char *fmt, uint8_t *data, ...);
/**
* Achieves the same effect as iso_struct_pack(), but the format is passed as
* a sequence of (int, char, char) triples. This list is terminated by
* (0, 0, 0) and the list of parameters follows.
*
* Example: iso_struct_pack_long(data, 4, '=', 'H', 0, 0, 0, &val) is the same
* as iso_struct_pack("4=H", 0, 0, 0, &val)
*/
int iso_struct_pack_long(uint8_t *data, ...);
/**
* Calculate the size of a given format string.
*
* \return The sum of the length of all formats in the string, in bytes. Return
* -1 on error.
*/
int iso_struct_calcsize(const char *fmt);
#endif