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29 * Copyright 2011 Develer S.r.l. (http://www.develer.com/)
33 * \brief Fletcher-32 checksum algorithm
35 * \author Francesco Sacchi <batt@develer.com>
38 #include "fletcher32.h"
39 #include <cfg/macros.h> //MIN()
41 void fletcher32_init(Fletcher32 *f)
48 void fletcher32_update(Fletcher32 *f, const void *_buf, size_t len)
51 const uint8_t *buf = (const uint8_t *)_buf;
52 uint8_t last = buf[len-1];
54 if (f->carry != -1 && len)
56 data = f->carry | *buf++ << 8;
62 data = buf[0] | buf[1] << 8;
72 size_t tlen = MIN(l, (size_t)360);
78 data = buf[0] | buf[1] << 8;
82 f->sum1 = (f->sum1 & 0xffff) + (f->sum1 >> 16);
83 f->sum2 = (f->sum2 & 0xffff) + (f->sum2 >> 16);
87 uint32_t fletcher32_final(Fletcher32 *f)
97 sum1 = (sum1 & 0xffff) + (sum1 >> 16);
98 sum2 = (sum2 & 0xffff) + (sum2 >> 16);
101 /* Second reduction step to reduce sums to 16 bits */
102 sum1 = (sum1 & 0xffff) + (sum1 >> 16);
103 sum2 = (sum2 & 0xffff) + (sum2 >> 16);
105 return sum2 << 16 | sum1;