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sys/hashes, sys/checksum: mv fletcher* checksum

pr/gpio
Ludwig Knüpfer 7 years ago
parent
1fedd456ce
commit
be4ac58e0c
6 changed files with 183 additions and 70 deletions
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  1. 40
      sys/checksum/fletcher16.c
  2. 40
      sys/checksum/fletcher32.c
  3. 39
      sys/hashes/hashes.c
  4. 51
      sys/include/checksum/fletcher16.h
  5. 52
      sys/include/checksum/fletcher32.h
  6. 31
      sys/include/hashes.h

40
sys/checksum/fletcher16.c
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@ -0,0 +1,40 @@
/*
* Copyright 2015 Eistec AB
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup sys_checksum_fletcher16
* @{
*
* @file
* @brief Fletcher16 implementation
*
* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
*
* @}
*/
#include "checksum/fletcher16.h"
uint16_t fletcher16(const uint8_t *data, size_t bytes)
{
uint16_t sum1 = 0xff, sum2 = 0xff;
while (bytes) {
size_t tlen = bytes > 20 ? 20 : bytes;
bytes -= tlen;
do {
sum2 += sum1 += *data++;
} while (--tlen);
sum1 = (sum1 & 0xff) + (sum1 >> 8);
sum2 = (sum2 & 0xff) + (sum2 >> 8);
}
/* Second reduction step to reduce sums to 8 bits */
sum1 = (sum1 & 0xff) + (sum1 >> 8);
sum2 = (sum2 & 0xff) + (sum2 >> 8);
return (sum2 << 8) | sum1;
}

40
sys/checksum/fletcher32.c
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@ -0,0 +1,40 @@
/*
* Copyright 2015 Eistec AB
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup sys_checksum_fletcher32
* @{
*
* @file
* @brief Fletcher32 implementation
*
* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
*
* @}
*/
#include "checksum/fletcher32.h"
uint32_t fletcher32(const uint16_t *data, size_t words)
{
uint32_t sum1 = 0xffff, sum2 = 0xffff;
while (words) {
unsigned tlen = words > 359 ? 359 : words;
words -= tlen;
do {
sum2 += sum1 += *data++;
} while (--tlen);
sum1 = (sum1 & 0xffff) + (sum1 >> 16);
sum2 = (sum2 & 0xffff) + (sum2 >> 16);
}
/* Second reduction step to reduce sums to 16 bits */
sum1 = (sum1 & 0xffff) + (sum1 >> 16);
sum2 = (sum2 & 0xffff) + (sum2 >> 16);
return (sum2 << 16) | sum1;
}

39
sys/hashes/hashes.c
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@ -12,7 +12,6 @@
* @file
* @author Jason Linehan <patientulysses@gmail.com>
* @author Christian Mehlis <mehlis@inf.fu-berlin.de>
* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
*/
#include "hashes.h"
@ -110,41 +109,3 @@ uint32_t one_at_a_time_hash(const uint8_t *buf, size_t len)
hash += hash << 15;
return hash;
}
uint16_t fletcher16(const uint8_t *data, size_t bytes)
{
uint16_t sum1 = 0xff, sum2 = 0xff;
while (bytes) {
size_t tlen = bytes > 20 ? 20 : bytes;
bytes -= tlen;
do {
sum2 += sum1 += *data++;
} while (--tlen);
sum1 = (sum1 & 0xff) + (sum1 >> 8);
sum2 = (sum2 & 0xff) + (sum2 >> 8);
}
/* Second reduction step to reduce sums to 8 bits */
sum1 = (sum1 & 0xff) + (sum1 >> 8);
sum2 = (sum2 & 0xff) + (sum2 >> 8);
return (sum2 << 8) | sum1;
}
uint32_t fletcher32(const uint16_t *data, size_t words)
{
uint32_t sum1 = 0xffff, sum2 = 0xffff;
while (words) {
unsigned tlen = words > 359 ? 359 : words;
words -= tlen;
do {
sum2 += sum1 += *data++;
} while (--tlen);
sum1 = (sum1 & 0xffff) + (sum1 >> 16);
sum2 = (sum2 & 0xffff) + (sum2 >> 16);
}
/* Second reduction step to reduce sums to 16 bits */
sum1 = (sum1 & 0xffff) + (sum1 >> 16);
sum2 = (sum2 & 0xffff) + (sum2 >> 16);
return (sum2 << 16) | sum1;
}

51
sys/include/checksum/fletcher16.h
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@ -0,0 +1,51 @@
/*
* Copyright (C) 2015 Eistec AB
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @defgroup sys_checksum_fletcher16 Fletcher16
* @ingroup sys_checksum
*
* @brief Fletcher16 checksum algorithm
* @{
*
* @file
* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
*/
#ifndef FLETCHER16_H
#define FLETCHER16_H
#include <stdlib.h>
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Fletcher's 16 bit checksum
*
* found on
* http://en.wikipedia.org/w/index.php?title=Fletcher%27s_checksum&oldid=661273016#Optimizations
*
* @note the returned sum is never 0
*
* @param buf input buffer to hash
* @param bytes length of buffer, in bytes
* @return 16 bit sized hash in the interval [1..65535]
*/
uint16_t fletcher16(const uint8_t *buf, size_t bytes);
#ifdef __cplusplus
}
#endif
#endif /* FLETCHER16_H */
/** @} */

52
sys/include/checksum/fletcher32.h
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@ -0,0 +1,52 @@
/*
* Copyright (C) 2015 Eistec AB
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @defgroup sys_checksum_fletcher32 Fletcher32
* @ingroup sys_checksum
*
* @brief Fletcher32 checksum algorithm
* @{
*
* @file
* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
*/
#ifndef FLETCHER32_H
#define FLETCHER32_H
#include <stdlib.h>
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Fletcher's 32 bit checksum
*
* found on
* http://en.wikipedia.org/w/index.php?title=Fletcher%27s_checksum&oldid=661273016#Optimizations
*
* @note the returned sum is never 0
* @note pay attention to alignment issues since this operates on an input
* buffer containing 16 bit words, not bytes.
*
* @param buf input buffer to hash
* @param words length of buffer, in 16 bit words
* @return 32 bit sized hash in the interval [1..2^32]
*/
uint32_t fletcher32(const uint16_t *buf, size_t words);
#ifdef __cplusplus
}
#endif
#endif /* FLETCHER32_H */
/** @} */

31
sys/include/hashes.h
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@ -17,7 +17,6 @@
*
* @author Jason Linehan <patientulysses@gmail.com>
* @author Christian Mehlis <mehlis@inf.fu-berlin.de>
* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
*/
#ifndef HASHES_H_
@ -158,36 +157,6 @@ uint32_t rotating_hash(const uint8_t *buf, size_t len);
*/
uint32_t one_at_a_time_hash(const uint8_t *buf, size_t len);
/**
* @brief Fletcher's 16 bit checksum
*
* found on
* http://en.wikipedia.org/w/index.php?title=Fletcher%27s_checksum&oldid=661273016#Optimizations
*
* @note the returned sum is never 0
*
* @param buf input buffer to hash
* @param bytes length of buffer, in bytes
* @return 16 bit sized hash in the interval [1..65535]
*/
uint16_t fletcher16(const uint8_t *buf, size_t bytes);
/**
* @brief Fletcher's 32 bit checksum
*
* found on
* http://en.wikipedia.org/w/index.php?title=Fletcher%27s_checksum&oldid=661273016#Optimizations
*
* @note the returned sum is never 0
* @note pay attention to alignment issues since this operates on an input
* buffer containing 16 bit words, not bytes.
*
* @param buf input buffer to hash
* @param words length of buffer, in 16 bit words
* @return 32 bit sized hash in the interval [1..2^32]
*/
uint32_t fletcher32(const uint16_t *buf, size_t words);
#ifdef __cplusplus
}
#endif

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