Joris Aerts / SDFileSystem

A re-written SDFileSystem library with improved compatibility, CRC support, and card removal/replacement support.

Dependencies:   FATFileSystem

Fork of SDFileSystem by Neil Thiessen

CRC7.cpp@16:dca379d55382, 2014-12-29 (annotated)

Committer:
jaerts
Date:
Mon Dec 29 15:26:39 2014 +0000
Revision:
16:dca379d55382
Parent:
0:2a6d8a096edc 
Add support for no card detect switch

Who changed what in which revision?

UserRevisionLine numberNew contents of line
neilt6 0:2a6d8a096edc 1 /* SD/MMC File System Library
neilt6 0:2a6d8a096edc 2 * Copyright (c) 2014 Neil Thiessen
neilt6 0:2a6d8a096edc 3 *
neilt6 0:2a6d8a096edc 4 * Licensed under the Apache License, Version 2.0 (the "License");
neilt6 0:2a6d8a096edc 5 * you may not use this file except in compliance with the License.
neilt6 0:2a6d8a096edc 6 * You may obtain a copy of the License at
neilt6 0:2a6d8a096edc 7 *
neilt6 0:2a6d8a096edc 8 * http://www.apache.org/licenses/LICENSE-2.0
neilt6 0:2a6d8a096edc 9 *
neilt6 0:2a6d8a096edc 10 * Unless required by applicable law or agreed to in writing, software
neilt6 0:2a6d8a096edc 11 * distributed under the License is distributed on an "AS IS" BASIS,
neilt6 0:2a6d8a096edc 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
neilt6 0:2a6d8a096edc 13 * See the License for the specific language governing permissions and
neilt6 0:2a6d8a096edc 14 * limitations under the License.
neilt6 0:2a6d8a096edc 15 */
neilt6 0:2a6d8a096edc 16
neilt6 0:2a6d8a096edc 17 #include "CRC7.h"
neilt6 0:2a6d8a096edc 18
neilt6 0:2a6d8a096edc 19 namespace
neilt6 0:2a6d8a096edc 20 {
neilt6 0:2a6d8a096edc 21 const char m_CRC7Table[] = {
neilt6 0:2a6d8a096edc 22 0x00, 0x09, 0x12, 0x1B, 0x24, 0x2D, 0x36, 0x3F,
neilt6 0:2a6d8a096edc 23 0x48, 0x41, 0x5A, 0x53, 0x6C, 0x65, 0x7E, 0x77,
neilt6 0:2a6d8a096edc 24 0x19, 0x10, 0x0B, 0x02, 0x3D, 0x34, 0x2F, 0x26,
neilt6 0:2a6d8a096edc 25 0x51, 0x58, 0x43, 0x4A, 0x75, 0x7C, 0x67, 0x6E,
neilt6 0:2a6d8a096edc 26 0x32, 0x3B, 0x20, 0x29, 0x16, 0x1F, 0x04, 0x0D,
neilt6 0:2a6d8a096edc 27 0x7A, 0x73, 0x68, 0x61, 0x5E, 0x57, 0x4C, 0x45,
neilt6 0:2a6d8a096edc 28 0x2B, 0x22, 0x39, 0x30, 0x0F, 0x06, 0x1D, 0x14,
neilt6 0:2a6d8a096edc 29 0x63, 0x6A, 0x71, 0x78, 0x47, 0x4E, 0x55, 0x5C,
neilt6 0:2a6d8a096edc 30 0x64, 0x6D, 0x76, 0x7F, 0x40, 0x49, 0x52, 0x5B,
neilt6 0:2a6d8a096edc 31 0x2C, 0x25, 0x3E, 0x37, 0x08, 0x01, 0x1A, 0x13,
neilt6 0:2a6d8a096edc 32 0x7D, 0x74, 0x6F, 0x66, 0x59, 0x50, 0x4B, 0x42,
neilt6 0:2a6d8a096edc 33 0x35, 0x3C, 0x27, 0x2E, 0x11, 0x18, 0x03, 0x0A,
neilt6 0:2a6d8a096edc 34 0x56, 0x5F, 0x44, 0x4D, 0x72, 0x7B, 0x60, 0x69,
neilt6 0:2a6d8a096edc 35 0x1E, 0x17, 0x0C, 0x05, 0x3A, 0x33, 0x28, 0x21,
neilt6 0:2a6d8a096edc 36 0x4F, 0x46, 0x5D, 0x54, 0x6B, 0x62, 0x79, 0x70,
neilt6 0:2a6d8a096edc 37 0x07, 0x0E, 0x15, 0x1C, 0x23, 0x2A, 0x31, 0x38,
neilt6 0:2a6d8a096edc 38 0x41, 0x48, 0x53, 0x5A, 0x65, 0x6C, 0x77, 0x7E,
neilt6 0:2a6d8a096edc 39 0x09, 0x00, 0x1B, 0x12, 0x2D, 0x24, 0x3F, 0x36,
neilt6 0:2a6d8a096edc 40 0x58, 0x51, 0x4A, 0x43, 0x7C, 0x75, 0x6E, 0x67,
neilt6 0:2a6d8a096edc 41 0x10, 0x19, 0x02, 0x0B, 0x34, 0x3D, 0x26, 0x2F,
neilt6 0:2a6d8a096edc 42 0x73, 0x7A, 0x61, 0x68, 0x57, 0x5E, 0x45, 0x4C,
neilt6 0:2a6d8a096edc 43 0x3B, 0x32, 0x29, 0x20, 0x1F, 0x16, 0x0D, 0x04,
neilt6 0:2a6d8a096edc 44 0x6A, 0x63, 0x78, 0x71, 0x4E, 0x47, 0x5C, 0x55,
neilt6 0:2a6d8a096edc 45 0x22, 0x2B, 0x30, 0x39, 0x06, 0x0F, 0x14, 0x1D,
neilt6 0:2a6d8a096edc 46 0x25, 0x2C, 0x37, 0x3E, 0x01, 0x08, 0x13, 0x1A,
neilt6 0:2a6d8a096edc 47 0x6D, 0x64, 0x7F, 0x76, 0x49, 0x40, 0x5B, 0x52,
neilt6 0:2a6d8a096edc 48 0x3C, 0x35, 0x2E, 0x27, 0x18, 0x11, 0x0A, 0x03,
neilt6 0:2a6d8a096edc 49 0x74, 0x7D, 0x66, 0x6F, 0x50, 0x59, 0x42, 0x4B,
neilt6 0:2a6d8a096edc 50 0x17, 0x1E, 0x05, 0x0C, 0x33, 0x3A, 0x21, 0x28,
neilt6 0:2a6d8a096edc 51 0x5F, 0x56, 0x4D, 0x44, 0x7B, 0x72, 0x69, 0x60,
neilt6 0:2a6d8a096edc 52 0x0E, 0x07, 0x1C, 0x15, 0x2A, 0x23, 0x38, 0x31,
neilt6 0:2a6d8a096edc 53 0x46, 0x4F, 0x54, 0x5D, 0x62, 0x6B, 0x70, 0x79
neilt6 0:2a6d8a096edc 54 };
neilt6 0:2a6d8a096edc 55 }
neilt6 0:2a6d8a096edc 56
neilt6 0:2a6d8a096edc 57 char CRC7(const char* data, int length)
neilt6 0:2a6d8a096edc 58 {
neilt6 0:2a6d8a096edc 59 //Calculate the CRC7 checksum for the specified data block
neilt6 0:2a6d8a096edc 60 char crc = 0;
neilt6 0:2a6d8a096edc 61 for (int i = 0; i < length; i++) {
neilt6 0:2a6d8a096edc 62 crc = m_CRC7Table[(crc << 1) ^ data[i]];
neilt6 0:2a6d8a096edc 63 }
neilt6 0:2a6d8a096edc 64
neilt6 0:2a6d8a096edc 65 //Return the calculated checksum
neilt6 0:2a6d8a096edc 66 return crc;
neilt6 0:2a6d8a096edc 67 }