Mercurial > yubikey-lua / file comparison
comparison: crc16/crc16.lua
crc16/crc16.lua
- changeset 0
- 598d09faf89c
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| -1:000000000000 | 0:598d09faf89c |
|---|---|
| 1 local bit = require "bit"; | |
| 2 | |
| 3 module "crc16" | |
| 4 | |
| 5 function hash(str) | |
| 6 local crc; | |
| 7 | |
| 8 local function initCrc() | |
| 9 crc = 0xffff; | |
| 10 end | |
| 11 | |
| 12 local function updCrc(byte) | |
| 13 crc = bit.bxor(crc, byte); | |
| 14 for i=1,8 do | |
| 15 local j = bit.band(crc, 1); | |
| 16 crc = bit.rshift(crc, 1); | |
| 17 if j ~= 0 then | |
| 18 crc = bit.bxor(crc, 0x8408); | |
| 19 end | |
| 20 end | |
| 21 end | |
| 22 | |
| 23 local function getCrc(str) | |
| 24 initCrc(); | |
| 25 for i = 1, #str do | |
| 26 updCrc(str:byte(i)); | |
| 27 end | |
| 28 return crc; | |
| 29 end | |
| 30 return getCrc(str); | |
| 31 end | |
| 32 | |
| 33 return { hash = hash } |
