quic_varint.h File Reference

QUIC variable-length integer coding (RFC 9000 sec 16). More...

#include "protocore_config.h"

Go to the source code of this file.

Classes
struct	QuicVarintNs
	Dispatch table. Addressed by offset, so the layout is asserted below. More...

Macros
#define	QUIC_VARINT_MAX   0x3FFFFFFFFFFFFFFFull
	Largest value a QUIC varint can hold (2^62 - 1).

Functions
	PROTOCORE_NS_LAYOUT (QuicVarintNs, len, encode, decode)
size_t	protocore_quic_varint_len (uint8_t *work, uint64_t value)
	Bytes value encodes to (1 / 2 / 4 / 8), or 0 if it exceeds .
size_t	protocore_quic_varint_encode (uint8_t *work, uint8_t *out, size_t cap, uint64_t value)
	Encode value in its shortest form. bytes written, or 0 on overflow .
proto_bool	protocore_quic_varint_decode (uint8_t *work, const uint8_t *in, size_t len, uint64_t *value, size_t *consumed)
	Decode a varint at in. Sets value and consumed (1/2/4/8). false if .

Variables
PROTOCORE_NS QuicVarintNs QuicVarint	PROTOCORE_UNUSED
	Module namespace.

Detailed Description

QUIC variable-length integer coding (RFC 9000 sec 16).

QUIC, HTTP/3 (RFC 9114), and QPACK (RFC 9204) encode most lengths and identifiers as a variable-length integer: the two most-significant bits of the first byte give the total length (00 -> 1 byte / 6-bit value, 01 -> 2 / 14-bit, 10 -> 4 / 30-bit, 11 -> 8 / 62-bit), and the remaining bits hold the value big-endian. The representable range is 0 .. 2^62-1.

This is the foundational primitive of the HTTP/3 stack. Pure and host-tested.

work is bytes the CALLER holds. This module reads none of them: it carries nothing between calls, so there is no state to keep and nothing to wipe. The parameter is there so a caller drives every namespace the same way.

Author

Douglas Quigg (dstroy0)

Date

2026

Definition in file quic_varint.h.

Macro Definition Documentation

QUIC_VARINT_MAX

#define QUIC_VARINT_MAX   0x3FFFFFFFFFFFFFFFull

Largest value a QUIC varint can hold (2^62 - 1).

Definition at line 35 of file quic_varint.h.

Function Documentation

PROTOCORE_NS_LAYOUT()

PROTOCORE_NS_LAYOUT	(	QuicVarintNs	,
		len	,
		encode	,
		decode
	)

protocore_quic_varint_len()

size_t protocore_quic_varint_len	(	uint8_t *	work,
		uint64_t	value
	)

Bytes value encodes to (1 / 2 / 4 / 8), or 0 if it exceeds .

Parameters

work	PROTOCORE_QUIC_VARINT_BORROW bytes the caller took. Not held past the call.
value	Value

Returns

The size_t.

protocore_quic_varint_encode()

size_t protocore_quic_varint_encode	(	uint8_t *	work,
		uint8_t *	out,
		size_t	cap,
		uint64_t	value
	)

Encode value in its shortest form. bytes written, or 0 on overflow .

Parameters

work	PROTOCORE_QUIC_VARINT_BORROW bytes the caller took. Not held past the call.
out	Out
cap	Cap
value	Value

Returns

The size_t.

protocore_quic_varint_decode()

proto_bool protocore_quic_varint_decode	(	uint8_t *	work,
		const uint8_t *	in,
		size_t	len,
		uint64_t *	value,
		size_t *	consumed
	)

Decode a varint at in. Sets value and consumed (1/2/4/8). false if .

Parameters

work	PROTOCORE_QUIC_VARINT_BORROW bytes the caller took. Not held past the call.
in	In
len	Len
value	Value
consumed	Consumed

Returns

PROTO_TRUE on success.

Variable Documentation

PROTOCORE_UNUSED

PROTOCORE_NS QuicVarintNs QuicVarint PROTOCORE_UNUSED

Initial value:

= {
    .len = protocore_quic_varint_len, .encode = protocore_quic_varint_encode, .decode = protocore_quic_varint_decode}

Module namespace.

Definition at line 75 of file quic_varint.h.