ref: 60ecd07e6d3f5786c8723dc9172c35d580fdadc8
dir: /appl/lib/crc.b/
implement Crc; include "crc.m"; init(poly : int, reg : int) : ref CRCstate { if (poly == 0) poly = int 16redb88320; tab := array[256] of int; for(i := 0; i < 256; i++){ crc := i; for(j := 0; j < 8; j++){ c := crc & 1; crc = (crc >> 1) & 16r7fffffff; if(c) crc ^= poly; } tab[i] = crc; } crcs := ref CRCstate; crcs.crc = 0; crcs.crctab = tab; crcs.reg = reg; return crcs; } crc(crcs : ref CRCstate, buf : array of byte, nb : int) : int { n := nb; if (n > len buf) n = len buf; crc := crcs.crc; tab := crcs.crctab; crc ^= crcs.reg; for (i := 0; i < n; i++) crc = tab[int(byte crc ^ buf[i])] ^ ((crc >> 8) & 16r00ffffff); crc ^= crcs.reg; crcs.crc = crc; return crc; } reset(crcs : ref CRCstate) { crcs.crc = 0; }