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mtbl_varint − Variable−width encoding and decoding of 32 and 64 bit integers


#include <mtbl.h>

unsigned mtbl_varint_length(uint64_t value);

unsigned mtbl_varint_length_packed(const uint8_t *buf, size_t len_buf);

size_t mtbl_varint_encode32(uint8_t *ptr, uint32_t value);

size_t mtbl_varint_encode64(uint8_t *ptr, uint64_t value);

size_t mtbl_varint_decode32(const uint8_t *ptr, uint32_t *value);

size_t mtbl_varint_decode64(const uint8_t *ptr, uint64_t *value);


mtbl_varint_encode32() and mtbl_varint_encode64() write the 32 or 64 bit quantity, respectively, in the argument value to the buffer in the argument dst. The quantity will be written in using a variable−width encoding that uses at most 5 bytes for a 32 bit quantity or 10 bytes for a 64 bit quantity.

mtbl_varint_decode32() and mtbl_varint_decode64() read the 32 or 64 bit varint quantity, respectively, in the argument ptr. The quantity read will be placed in the argument value.

Bounds checking must be performed by the caller.


mtbl_varint_encode32() and mtbl_varint_encode64() return the number of bytes written to dst.

mtbl_varint_decode32() and mtbl_varint_decode64() return the number of bytes read from ptr.

mtbl_varint_length() returns the number of bytes that its argument value would require in the variable−width encoding.

mtbl_varint_length_packed() returns the number of bytes consumed by the variable−width encoded quantity at its argument data. It will read at most len_buf bytes from data. The value 0 is returned if a valid varint is not present.