Karina
45 lines
989 B
C
45 lines
989 B
C
// SPDX-License-Identifier: GPL-3.0-or-later
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// Copyright (c) 2026 0xKarinyash
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#include "bootinfo.h"
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#include <lib/Rand.h>
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#include <OSCPU.h>
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#include <types.h>
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static UInt64 sPseudorandState = 0;
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static inline UInt64 RDTSC() {
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UInt32 lo, hi;
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__asm__ volatile ("rdtsc" : "=a" (lo), "=d" (hi));
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return ((UInt64)hi << 32) | lo;
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}
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void RandInitialize() {
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sPseudorandState = RDTSC();
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if (sPseudorandState == 0) sPseudorandState = BOOTINFO_MAGIC; // why not reuse "termOS"?
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}
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static UInt64 RandXorshift() {
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UInt64 x = sPseudorandState;
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x ^= x << 13;
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x ^= x >> 7;
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x ^= x << 17;
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return sPseudorandState = x;
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}
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static bool RandHardware(UInt64 *value) {
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UInt8 ok;
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__asm__ volatile ("rdrand %0; setc %1"
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: "=r" (*value), "=qm" (ok));
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return ok != 0;
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}
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UInt64 Rand() {
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UInt64 result;
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if (OSCPUHasFeature(kCPUFeatureRDRAND)) {
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if (RandHardware(&result)) return result;
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}
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return RandXorshift();
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} |