include/tinyhtm/varint.h File Reference

Variable length integer encoding/decoding. More...

#include "common.h"

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Functions
HTM_INLINE unsigned int	htm_varint_len (uint64_t val)
	Returns the number of bytes required to represent val.
HTM_INLINE unsigned int	htm_varint_nfollow (unsigned char leadbyte)
	Returns the number of bytes following the specified leading byte (in a variable length coding of an unsigned integer).
HTM_INLINE uint64_t	htm_varint_decode (const unsigned char *buf)
	Decodes the variable length integer encoded at buf.
HTM_INLINE unsigned int	htm_varint_encode (unsigned char *buf, const uint64_t val)
	Variable-length encodes val into the given buffer, which must point to a buffer of at least 8 bytes.
HTM_INLINE unsigned int	htm_varint_rencode (unsigned char *buf, const uint64_t val)
	Variable-length encodes val into the given buffer, which must point to a buffer of at least 8 bytes.

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Detailed Description

Variable length integer encoding/decoding.

The scheme employed here is as follows: an unsigned integer is mapped to a sequence of bytes. The 3 MSBs of the first byte contain the number of subsequent bytes in the sequence, and the 5 LSBs contain the 5 MSBs of the value. Bytes after the first contain the remaining bits of the value, from most to least significant. The smallest representable integer is 0, the largest 2^61 - 1.

Authors:

Serge Monkewitz

Copyright:

IPAC/Caltech

Definition in file varint.h.