Re: Searching Fast CRC

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Most fast CRC routines use a fixed lookup table with 256 entries.  Since
the entries are fixed they usually go into ROM, not RAM.  For 32 bits,
each entry would be 4 bytes, so you would need 1024 bytes of ROM.


Re: Searching Fast CRC

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Note that it isn't a 256 _byte_ table: it is a 256 _entry_ table.  The
size of the CRC determines the size of the entry.  The word size of the
host processor usually has nothing to do with it (unless it imposes
restrictions on the size of entries in an indexed table).

For a 32-bit CRC, each table entry is 32 bits, hence you need 256
"words" on a 32-bit processor (1024 bytes).

The original poster was talking about a 16-bit CRC.  In this case, the
256 entries would each be 16 bits, and therefore occupy 512 bytes of

David Empson

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