| // SPDX-License-Identifier: LGPL-2.1-or-later |
| /* |
| * |
| * BlueZ - Bluetooth protocol stack for Linux |
| * |
| * Copyright (C) 2011-2014 Intel Corporation |
| * Copyright (C) 2002-2010 Marcel Holtmann <marcel@holtmann.org> |
| * |
| * |
| */ |
| |
| #ifdef HAVE_CONFIG_H |
| #include <config.h> |
| #endif |
| |
| #include "crc.h" |
| |
| uint32_t crc24_bit_reverse(uint32_t value) |
| { |
| uint32_t result = 0; |
| uint8_t i; |
| |
| for (i = 0; i < 24; i++) |
| result |= ((value >> i) & 1) << (23 - i); |
| |
| return result; |
| } |
| |
| uint32_t crc24_calculate(uint32_t preset, const uint8_t *data, uint8_t len) |
| { |
| uint32_t state = preset; |
| uint8_t i; |
| |
| for (i = 0; i < len; i++) { |
| uint8_t n, cur = data[i]; |
| |
| for (n = 0; n < 8; n++) { |
| int next_bit = (state ^ cur) & 1; |
| |
| cur >>= 1; |
| state >>= 1; |
| if (next_bit) { |
| state |= 1 << 23; |
| state ^= 0x5a6000; |
| } |
| } |
| } |
| |
| return state; |
| } |
| |
| uint32_t crc24_reverse(uint32_t crc, const uint8_t *data, uint8_t len) |
| { |
| uint32_t state = crc; |
| uint8_t i; |
| |
| for (i = 0; i < len; i++) { |
| uint8_t n, cur = data[len - i - 1]; |
| |
| for (n = 0; n < 8; n++) { |
| int top_bit = state >> 23; |
| |
| state = (state << 1) & 0xffffff; |
| state |= top_bit ^ ((cur >> (7 - n)) & 1); |
| if (top_bit) |
| state ^= 0xb4c000; |
| } |
| } |
| |
| return state; |
| } |