Atmosphere/libraries/libstratosphere/source/cal/cal_crc_utils.cpp

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/*
* Copyright (c) Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stratosphere.hpp>
#include "cal_crc_utils.hpp"
namespace ams::cal::impl {
namespace {
constexpr inline const u16 CrcTable[0x10] = {
0x0000, 0xCC01, 0xD801, 0x1400, 0xF001, 0x3C00, 0x2800, 0xE401,
0xA001, 0x6C00, 0x7800, 0xB401, 0x5000, 0x9C01, 0x8801, 0x4400
};
}
u16 CalculateCrc16(const void *data, size_t size) {
AMS_ASSERT(data != nullptr);
u16 crc = 0x55AA;
const u8 *data_u8 = static_cast<const u8 *>(data);
for (size_t i = 0; i < size; ++i) {
crc = (crc >> 4) ^ (CrcTable[crc & 0xF]) ^ (CrcTable[(data_u8[i] >> 0) & 0xF]);
crc = (crc >> 4) ^ (CrcTable[crc & 0xF]) ^ (CrcTable[(data_u8[i] >> 4) & 0xF]);
}
return crc;
}
Result ValidateCalibrationCrc(const void *data, size_t size) {
AMS_ASSERT(data != nullptr);
AMS_ASSERT(size >= sizeof(u16));
const u16 crc = *reinterpret_cast<const u16 *>(reinterpret_cast<uintptr_t>(data) + size - sizeof(u16));
R_UNLESS(CalculateCrc16(data, size - sizeof(u16)) == crc, cal::ResultCalibrationDataCrcError());
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R_SUCCEED();
}
}