Description of The Algorithm
As mentioned above, this algorithm computes a checksum by segmenting the data and adding it to an accumulator that is circular right shifted between each summation. To keep the accumulator within return value bounds, bit-masking with 1's is done.
Example: 4-bit checksum using 4-bit sized segments (big-endian:Endianness)
Loop 1:
checksum: 0000 seg: 1011a) Circular shift checksum:
0000 -> 0000b) Add seg and bitmask:
0000 + 1011 = 1011 -> 1011 & 1111 = 1011Loop 2:
checksum: 1011 seg: 1000a) Circular shift checksum:
1011 -> 1101b) Add seg and bitmask:
1101 + 1000 = 10101 -> 10101 & 1111 = 0101Loop 3:
checksum: 0101 seg: 1110a) Circular shift checksum:
0101 -> 1010b) Add seg and bitmask:
1010 + 1110 = 11000 -> 11000 & 1111 = 1000Checksum: 1000
Read more about this topic: BSD Checksum
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