1/*
2 * Copyright (c) 2012 Apple, Inc. All Rights Reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. Please obtain a copy of the License at
10 * http://www.opensource.apple.com/apsl/ and read it before using this
11 * file.
12 *
13 * The Original Code and all software distributed under the License are
14 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
15 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
16 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
18 * Please see the License for the specific language governing rights and
19 * limitations under the License.
20 *
21 * @APPLE_LICENSE_HEADER_END@
22 */
23
24
25
26#include "crc.h"
27
28uint64_t
29crc_normal_init(crcInfoPtr crc)
30{
31    dispatch_once(&crc->table_init, ^{
32        gen_std_crc_table(crc);
33    });
34    return crc->descriptor->def.parms.initial_value;
35}
36
37static inline uint8_t
38crc_table_value8(uint8_t *table, uint8_t p, uint8_t crc) {
39    return table[((crc) ^ p) & 0xff] ^ (crc << 8);
40}
41
42static inline uint16_t
43crc_table_value16(uint16_t *table, uint8_t p, uint16_t crc) {
44    return table[((crc>>8) ^ p) & 0xff] ^ (crc << 8);
45}
46
47static inline uint32_t
48crc_table_value32(uint32_t *table, uint8_t p, uint32_t crc) {
49    return table[((crc>>24) ^ p) & 0xff] ^ (crc << 8);
50}
51
52static inline uint64_t
53crc_table_value64(uint64_t *table, uint8_t p, uint64_t crc) {
54    return table[((crc>>56) ^ p) & 0xffULL] ^ (crc << 8);
55}
56
57
58uint64_t
59crc_normal_update(crcInfoPtr crc, uint8_t *p, size_t len, uint64_t current)
60{
61    while (len--) {
62        switch (crc->descriptor->def.parms.width) {
63            case 1: current = crc_table_value8(crc->table.bytes, *p, (uint8_t) current); break;
64            case 2: current = crc_table_value16(crc->table.b16, *p, (uint16_t) current); break;
65            case 4: current = crc_table_value32(crc->table.b32, *p, (uint32_t) current); break;
66            case 8: current = crc_table_value64(crc->table.b64, *p, current); break;
67        }
68        p++;
69    }
70    return current & descmaskfunc(crc->descriptor);
71}
72
73
74uint64_t
75crc_normal_final(crcInfoPtr crc, uint64_t current)
76{
77    return current ^ crc->descriptor->def.parms.final_xor & descmaskfunc(crc->descriptor);
78}
79
80uint64_t
81crc_normal_oneshot(crcInfoPtr crc, uint8_t *p, size_t len)
82{
83    dispatch_once(&crc->table_init, ^{
84        gen_std_crc_table(crc);
85    });
86    uint64_t current = crc->descriptor->def.parms.initial_value;
87    while (len--) {
88        switch (crc->descriptor->def.parms.width) {
89            case 1: current = crc_table_value8(crc->table.bytes, *p, (uint8_t) current); break;
90            case 2: current = crc_table_value16(crc->table.b16, *p, (uint16_t) current); break;
91            case 4: current = crc_table_value32(crc->table.b32, *p, (uint32_t) current); break;
92            case 8: current = crc_table_value64(crc->table.b64, *p, current); break;
93        }
94        p++;
95    }
96    return current ^ crc->descriptor->def.parms.final_xor;
97}
98