mirror of
https://github.com/google/pebble.git
synced 2025-04-30 07:21:39 -04:00
64 lines
2.2 KiB
C
64 lines
2.2 KiB
C
/*
|
|
* Copyright 2024 Google LLC
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <stdbool.h>
|
|
#include <stddef.h>
|
|
#include <stdint.h>
|
|
|
|
//! An implementation of Consistent Overhead Byte Stuffing
|
|
//!
|
|
//! http://conferences.sigcomm.org/sigcomm/1997/papers/p062.pdf
|
|
//! http://en.wikipedia.org/wiki/Consistent_Overhead_Byte_Stuffing
|
|
|
|
//! Evaluates to the offset required when encoding in-place
|
|
#define COBS_OVERHEAD(n) (((n) + 253) / 254)
|
|
//! Evaluates to the maximum buffer size required to hold n bytes of data
|
|
//! after COBS encoding.
|
|
#define MAX_SIZE_AFTER_COBS_ENCODING(n) ((n) + COBS_OVERHEAD(n))
|
|
|
|
typedef struct CobsDecodeContext {
|
|
char *output;
|
|
size_t output_length;
|
|
size_t decoded_length;
|
|
uint8_t payload_remaining;
|
|
bool block_is_terminated;
|
|
} CobsDecodeContext;
|
|
|
|
//! Initialize the COBS decoding context.
|
|
void cobs_streaming_decode_start(CobsDecodeContext * restrict ctx,
|
|
void * restrict output_buffer,
|
|
size_t length);
|
|
|
|
//! Decode a byte in the COBS stream.
|
|
//!
|
|
//! @return false if decoding has failed.
|
|
bool cobs_streaming_decode(CobsDecodeContext * restrict ctx, char in);
|
|
|
|
//! Complete a COBS stream.
|
|
//!
|
|
//! @return length of decoded stream, or SIZE_MAX if decoding has failed.
|
|
size_t cobs_streaming_decode_finish(CobsDecodeContext * restrict ctx);
|
|
|
|
//! COBS-encode a buffer out to another buffer.
|
|
//!
|
|
//! @param [out] dst destination buffer. The buffer must be at least
|
|
//! MAX_SIZE_AFTER_COBS_ENCODING(length) bytes long.
|
|
//! @param [in] src source buffer
|
|
//! @param length length of src
|
|
size_t cobs_encode(void * restrict dst, const void * restrict src,
|
|
size_t length);
|