1 files changed, 210 insertions, 0 deletions
diff --git a/src/VBox/Runtime/common/rand/randparkmiller.cpp b/src/VBox/Runtime/common/rand/randparkmiller.cpp
new file mode 100644
index 00000000..df6232fe
--- /dev/null
+++ b/src/VBox/Runtime/common/rand/randparkmiller.cpp
@@ -0,0 +1,210 @@
+/* $Id: randparkmiller.cpp $ */
+/** @file
+ * IPRT - Random Numbers, Park-Miller Pseudo Random.
+ */
+
+/*
+ * Copyright (C) 2008-2019 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/rand.h>
+#include "internal/iprt.h"
+
+#include <iprt/asm-math.h>
+#include <iprt/mem.h>
+#include <iprt/string.h>
+#include <iprt/errcore.h>
+#include "internal/rand.h"
+#include "internal/magics.h"
+
+
+
+DECLINLINE(uint32_t) rtRandParkMillerU31(uint32_t *pu32Ctx)
+{
+    /*
+     * Park-Miller random number generator:
+     *      X2 = X1 * g mod n.
+     *
+     * We use the constants suggested by Park and Miller:
+     *      n = 2^31 - 1 = INT32_MAX
+     *      g = 7^5 = 16807
+     *
+     * This will produce numbers in the range [0..INT32_MAX-1], which is
+     * almost 31-bits. We'll ignore the missing number for now and settle
+     * for just filling in the missing bit instead (the caller does this).
+     */
+    uint32_t x1 = *pu32Ctx;
+    if (!x1)
+        x1 = 20080806;
+    /*uint32_t x2 = ((uint64_t)x1 * 16807) % INT32_MAX;*/
+    uint32_t x2 = ASMModU64ByU32RetU32(ASMMult2xU32RetU64(x1, 16807), INT32_MAX);
+    return *pu32Ctx = x2;
+}
+
+
+/** @copydoc RTRANDINT::pfnGetU32 */
+static DECLCALLBACK(uint32_t) rtRandParkMillerGetU32(PRTRANDINT pThis, uint32_t u32First, uint32_t u32Last)
+{
+    uint32_t off;
+    uint32_t offLast = u32Last - u32First;
+    if (offLast == UINT32_MAX)
+    {
+        /* 30 + 2 bit (make up for the missing INT32_MAX value) */
+        off = rtRandParkMillerU31(&pThis->u.ParkMiller.u32Ctx);
+        if (pThis->u.ParkMiller.cBits < 2)
+        {
+            pThis->u.ParkMiller.u32Bits = rtRandParkMillerU31(&pThis->u.ParkMiller.u32Ctx);
+            pThis->u.ParkMiller.cBits = 30;
+        }
+        off >>= 1;
+        off |= (pThis->u.ParkMiller.u32Bits & 3) << 30;
+        pThis->u.ParkMiller.u32Bits >>= 2;
+        pThis->u.ParkMiller.cBits -= 2;
+    }
+    else if (offLast == (uint32_t)INT32_MAX - 1)
+        /* The exact range. */
+        off = rtRandParkMillerU31(&pThis->u.ParkMiller.u32Ctx);
+    else if (offLast < UINT32_C(0x07ffffff))
+    {
+        /* Requested 23 or fewer bits, just lose the lower bit. */
+        off = rtRandParkMillerU31(&pThis->u.ParkMiller.u32Ctx);
+        off >>= 1;
+        off %= (offLast + 1);
+    }
+    else
+    {
+        /*
+         * 30 + 6 bits.
+         */
+        uint64_t off64 = rtRandParkMillerU31(&pThis->u.ParkMiller.u32Ctx);
+        if (pThis->u.ParkMiller.cBits < 6)
+        {
+            pThis->u.ParkMiller.u32Bits = rtRandParkMillerU31(&pThis->u.ParkMiller.u32Ctx);
+            pThis->u.ParkMiller.cBits = 30;
+        }
+        off64 >>= 1;
+        off64 |= (uint64_t)(pThis->u.ParkMiller.u32Bits & 0x3f) << 30;
+        pThis->u.ParkMiller.u32Bits >>= 6;
+        pThis->u.ParkMiller.cBits -= 6;
+        off = ASMModU64ByU32RetU32(off64, offLast + 1);
+    }
+    return off + u32First;
+}
+
+
+/** @copydoc RTRANDINT::pfnSeed */
+static DECLCALLBACK(int) rtRandParkMillerSeed(PRTRANDINT pThis, uint64_t u64Seed)
+{
+    pThis->u.ParkMiller.u32Ctx = (uint32_t)u64Seed;
+    pThis->u.ParkMiller.u32Bits = 0;
+    pThis->u.ParkMiller.cBits = 0;
+    return VINF_SUCCESS;
+}
+
+
+/** @copydoc RTRANDINT::pfnSaveState */
+static DECLCALLBACK(int) rtRandParkMillerSaveState(PRTRANDINT pThis, char *pszState, size_t *pcbState)
+{
+#define RTRAND_PARKMILLER_STATE_SIZE (3+8+1+8+1+2+1+1)
+
+    if (*pcbState < RTRAND_PARKMILLER_STATE_SIZE)
+    {
+        *pcbState = RTRAND_PARKMILLER_STATE_SIZE;
+        return VERR_BUFFER_OVERFLOW;
+    }
+    RTStrPrintf(pszState, *pcbState, "PM:%08RX32,%08RX32,%02x;",
+                pThis->u.ParkMiller.u32Ctx,
+                pThis->u.ParkMiller.u32Bits,
+                pThis->u.ParkMiller.cBits);
+    return VINF_SUCCESS;
+}
+
+
+/** @copydoc RTRANDINT::pfnRestoreState */
+static DECLCALLBACK(int) rtRandParkMillerRestoreState(PRTRANDINT pThis, char const *pszState)
+{
+    /* marker */
+    if (    pszState[0] != 'P'
+        ||  pszState[1] != 'M'
+        ||  pszState[2] != ':')
+        return VERR_PARSE_ERROR;
+    pszState += 3;
+
+    /* u32Ctx */
+    char *pszNext = NULL;
+    uint32_t u32Ctx;
+    int rc = RTStrToUInt32Ex(pszState, &pszNext, 16, &u32Ctx);
+    if (    rc != VWRN_TRAILING_CHARS
+        ||  pszNext !=  pszState + 8
+        ||  *pszNext != ',')
+        return VERR_PARSE_ERROR;
+    pszState += 8 + 1;
+
+    /* u32Bits */
+    uint32_t u32Bits;
+    rc = RTStrToUInt32Ex(pszState, &pszNext, 16, &u32Bits);
+    if (    rc != VWRN_TRAILING_CHARS
+        ||  pszNext !=  pszState + 8
+        ||  *pszNext != ',')
+        return VERR_PARSE_ERROR;
+    pszState += 8 + 1;
+
+    /* cBits */
+    uint32_t cBits;
+    rc = RTStrToUInt32Ex(pszState, &pszNext, 16, &cBits);
+    if (    rc != VWRN_TRAILING_CHARS
+        ||  pszNext !=  pszState + 2
+        ||  *pszNext != ';'
+        ||  pszNext[1] != '\0')
+        return VERR_PARSE_ERROR;
+
+    /* commit */
+    pThis->u.ParkMiller.u32Ctx  = u32Ctx;
+    pThis->u.ParkMiller.u32Bits = u32Bits;
+    pThis->u.ParkMiller.cBits   = cBits;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTRandAdvCreateParkMiller(PRTRAND phRand) RT_NO_THROW_DEF
+{
+    PRTRANDINT pThis = (PRTRANDINT)RTMemAlloc(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+    pThis->u32Magic = RTRANDINT_MAGIC;
+    pThis->pfnGetBytes= rtRandAdvSynthesizeBytesFromU32;
+    pThis->pfnGetU32  = rtRandParkMillerGetU32;
+    pThis->pfnGetU64  = rtRandAdvSynthesizeU64FromU32;
+    pThis->pfnSeed    = rtRandParkMillerSeed;
+    pThis->pfnSaveState = rtRandParkMillerSaveState;
+    pThis->pfnRestoreState = rtRandParkMillerRestoreState;
+    pThis->pfnDestroy = rtRandAdvDefaultDestroy;
+    pThis->u.ParkMiller.u32Ctx = 0x20080806;
+    pThis->u.ParkMiller.u32Bits = 0;
+    pThis->u.ParkMiller.cBits = 0;
+    *phRand = pThis;
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTRandAdvCreateParkMiller);
+