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