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/* IBM_PROLOG_BEGIN_TAG */
/* This is an automatically generated prolog. */
/* */
/* $Source: src/lib/ppc405lib/lfsr.c $ */
/* */
/* OpenPOWER OnChipController Project */
/* */
/* Contributors Listed Below - COPYRIGHT 2015 */
/* [+] International Business Machines Corp. */
/* */
/* */
/* Licensed under the Apache License, Version 2.0 (the "License"); */
/* you may not use this file except in compliance with the License. */
/* You may obtain a copy of the License at */
/* */
/* http://www.apache.org/licenses/LICENSE-2.0 */
/* */
/* Unless required by applicable law or agreed to in writing, software */
/* distributed under the License is distributed on an "AS IS" BASIS, */
/* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or */
/* implied. See the License for the specific language governing */
/* permissions and limitations under the License. */
/* */
/* IBM_PROLOG_END_TAG */
// $Id$
/// \file lfsr.c
/// \brief
#include <stdint.h>
#include "lfsr.h"
// Parity for 4-bit numbers
static uint8_t S_parity4[16] = {
0, 1, 1, 0,
1, 0, 0, 1,
1, 0, 0, 1,
0, 1, 1, 0
};
// 64, 63, 61, 60 LFSR. The routine is coded with the uint8_t casting to help
// the compiler generate more efficient code.
void
_lfsr64(uint64_t* io_seed)
{
*io_seed = (*io_seed << 1) |
S_parity4[(uint8_t)((*io_seed >> 59) & 0x3) |
(uint8_t)((*io_seed >> 60) & 0xc)];
}
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