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/* Copyright 2017 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
/* Base-32 encoding/decoding, designed for manual operator entry. */
#ifndef __CROS_EC_BASE32_H
#define __CROS_EC_BASE32_H
/* Symbol map for base32 encoding */
extern const char base32_map[33];
/**
* CRC-5-USB Initially created for USB Token Packets. It uses
* the generator polynomial X^5 + X^2 + X^0 and is 5-bits.
*
* @param sym New symbol to update CRC with
* @param previous_crc Existing CRC value
* @return The updated CRC.
*/
uint8_t crc5_sym(uint8_t sym, uint8_t previous_crc);
/**
* base32-encode data into a null-terminated string
*
* Uses A-Z0-9 encoding, skipping I,O,0,1 since they're easy to get mixed up.
*
* @param dest Destination buffer; set to empty string on
* error
* @param destlen_chars Length of destination buffer in characters
* @param src Source binary data
* @param srclen_bits Length of source *in bits*. If this is not a
* multiple of 8, the *most significant* bits of
* the last byte will be used. If this is not a
* multiple of 5, the least significant bits of
* the last symbol will be padded with 0 bits.
* @param add_crc_every If non-zero, add a CRC symbol after each group
* of this many symbols. There must be an exact
* number of groups; that is, ceil(srclen_bits/5)
* must be a multiple of add_crc_every.
* @return EC_SUCCESS, or non-zero error code.
*/
int base32_encode(char *dest, int destlen_chars,
const void *srcbits, int srclen_bits,
int add_crc_every);
/**
* base32-decode data from a null-terminated string
*
* Ignores whitespace and '-' dashes in the source string.
*
* If the destination is smaller than the decoded bitstream, only that many
* bits will be decoded. This is useful for decoding the first part of a
* bitstream to look for a struct version.
*
* If the destination is larger than the decoded bitstream, check the return
* value to determine how many bits were decoded from the source. Note that if
* padding was added by base32_encode (that is, the input length was not a
* multiple of 5 bits), the padding will be included in the count.
*
* @param dest Destination; must be at least
* ceil(destlen_bits/8) bytes.
* @param destlen_bits Length of destination *in bits*.
* @param src Source string (null-terminated)
* @param crc_after_every If non-zero, expect CRC symbol after every
* group of this many symbols.
* @return Number of decoded *bits*, or -1 if error.
*/
int base32_decode(uint8_t *dest, int destlen_bits, const char *src,
int crc_after_every);
#endif
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