From f2de13d61b1032146872f57afa0db1fcaa56997c Mon Sep 17 00:00:00 2001 From: Tobias Platen Date: Tue, 22 Nov 2022 20:43:46 +0100 Subject: [PATCH] coldboot: add lfsr.h by Anton Blanchard --- coldboot/lfsr.h | 109 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 109 insertions(+) create mode 100644 coldboot/lfsr.h diff --git a/coldboot/lfsr.h b/coldboot/lfsr.h new file mode 100644 index 0000000..8326b81 --- /dev/null +++ b/coldboot/lfsr.h @@ -0,0 +1,109 @@ +#include + +/* + * Copyright (C) 2020, Anton Blanchard , IBM + * + * Redistribution and use in source and binary forms, with or without modification, + * are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, this + * list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR + * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON + * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +/* + * Galois LFSR + * + * Polynomials verified with https://bitbucket.org/gallen/mlpolygen/ + */ +static inline unsigned long lfsr(unsigned long bits, unsigned long prev) +{ + static const unsigned long lfsr_taps[] = { + 0x0, + 0x0, + 0x3, + 0x6, + 0xc, + 0x14, + 0x30, + 0x60, + 0xb8, + 0x110, + 0x240, + 0x500, + 0x829, + 0x100d, + 0x2015, + 0x6000, + 0xd008, + 0x12000, + 0x20400, + 0x40023, + 0x90000, + 0x140000, + 0x300000, + 0x420000, + 0xe10000, + 0x1200000, + 0x2000023, + 0x4000013, + 0x9000000, + 0x14000000, + 0x20000029, + 0x48000000, + 0x80200003, +#ifdef __LP64__ + 0x100080000, + 0x204000003, + 0x500000000, + 0x801000000, + 0x100000001f, + 0x2000000031, + 0x4400000000, + 0xa000140000, + 0x12000000000, + 0x300000c0000, + 0x63000000000, + 0xc0000030000, + 0x1b0000000000, + 0x300003000000, + 0x420000000000, + 0xc00000180000, + 0x1008000000000, + 0x3000000c00000, + 0x6000c00000000, + 0x9000000000000, + 0x18003000000000, + 0x30000000030000, + 0x40000040000000, + 0xc0000600000000, + 0x102000000000000, + 0x200004000000000, + 0x600003000000000, + 0xc00000000000000, + 0x1800300000000000, + 0x3000000000000030, + 0x6000000000000000, + 0x800000000000000d +#endif + }; + unsigned long lsb = prev & 1; + + prev >>= 1; + prev ^= (-lsb) & lfsr_taps[bits]; + + return prev; +} -- 2.30.2