tcobs.h

/*! \file tcobs.h
\author thomas.hoehenleitner [at] seerose.net
\details See ./TCOBSv1Specification.md.
*******************************************************************************/

#ifndef TCOBS_H_
#define TCOBS_H_

#ifdef __cplusplus
extern "C" {
#endif

#include <stddef.h>

//! TCOBSEncode stuffs "length" bytes of data beginning at the location pointed to by "input" and writes the output to the
//! location pointed to by "output". Returns the number of bytes written to "output" or a negative value in error case.
//! A 0-delimiter is NOT added as last byte allowing concatenating TCOBS encoded buffers to one bigger buffer before the
//! 00-byte delimiting. Buffer overlapping is allowed, when input lays inside output with a sufficient offset. The offset
//! should be >= next large whole number of length/31. because in the worst case for each 31 bytes an additional sigil byte
//! is inserted. The provided output buffer size should be >= length + next large whole number of length/31. This is a
//! responsibility of the caller and not checked for efficiency.
//! If your compiler uses a pre-C99 C dialect and does not know The "__restrict" keyword, you can define it in the project settings.
int TCOBSEncode(void* __restrict output, const void* __restrict input, size_t length);

//! TCOBSDecode decodes data ending at the location pointed to by "input" backwards (starting with the last byte)
//! and writes the output also backwards to the location pointed to by "output" with a maximum size of max.
//! Returns the number of bytes written to "output". Only max bytes are written. If the returned value is
//! > max, this is an error "output buffer too small". In case of an error, a negative value is returned.
//! THIS IS **IMPORTANT**: The decoded data start at output+max-returned, because output is filled from the end.
//! Buffer overlapping is partially possible if output limit is _behind_ input limit with sufficient distance,
//! but data can get much longer.
//! If your compiler uses a pre-C99 C dialect and does not know The "__restrict" keyword, you can define it in the project settings.
int TCOBSDecode(void* __restrict output, size_t max, const void* __restrict input, size_t length);

#define OUT_BUFFER_TOO_SMALL -1000000 //!< OUT_BUFFER_TOO_SMALL is TCOBSDecode return error code.
#define INPUT_DATA_CORRUPTED -2000000 //!< INPUT_DATA_CORRUPTED is TCOBSDecode return error code.

#ifdef __cplusplus
}
#endif

#endif // TCOBS_H_