1 files changed, 107 insertions, 0 deletions
diff --git a/src/VBox/Runtime/common/asm/ASMBitFirstSet-generic.cpp b/src/VBox/Runtime/common/asm/ASMBitFirstSet-generic.cpp
new file mode 100644
index 00000000..308f33d7
--- /dev/null
+++ b/src/VBox/Runtime/common/asm/ASMBitFirstSet-generic.cpp
@@ -0,0 +1,107 @@
+/* $Id: ASMBitFirstSet-generic.cpp $ */
+/** @file
+ * IPRT - ASMBitFirstSet - generic C implementation.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that 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 <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/asm.h>
+#include "internal/iprt.h"
+
+#include <iprt/assert.h>
+
+
+RTDECL(int32_t) ASMBitFirstSet(const volatile void RT_FAR *pvBitmap, uint32_t cBits) RT_NOTHROW_DEF
+{
+    const volatile size_t RT_FAR *pu = (const volatile size_t RT_FAR *)pvBitmap;
+    Assert(!(cBits & 31));
+    Assert(!((uintptr_t)pvBitmap & 3));
+
+#if ARCH_BITS > 32
+    /* Deal with misaligned bitmaps (happens all the time via ASMBitNextClear()). */
+    if (!((uintptr_t)pvBitmap & 7) && cBits >= 32)
+    {
+        uint32_t u32 = *(const volatile uint32_t RT_FAR *)pu;
+        if (u32 != 0)
+        {
+            size_t const iBaseBit = ((uintptr_t)pu - (uintptr_t)pvBitmap) * 8;
+            return iBaseBit + ASMBitFirstSetU32(RT_LE2H_U32(u32)) - 1;
+        }
+        pu     = (const volatile size_t RT_FAR *)((uintptr_t)pu + sizeof(uint32_t));
+        cBits -= 32;
+    }
+#endif
+
+    /* Main search loop: */
+    while (cBits >= sizeof(size_t) * 8)
+    {
+        size_t u = *pu;
+        if (u == 0)
+        { }
+        else
+        {
+            size_t const iBaseBit = ((uintptr_t)pu - (uintptr_t)pvBitmap) * 8;
+#if ARCH_BITS == 32
+            return iBaseBit + ASMBitFirstSetU32(RT_LE2H_U32(u)) - 1;
+#elif ARCH_BITS == 64
+            return iBaseBit + ASMBitFirstSetU64(RT_LE2H_U64(u)) - 1;
+#else
+# error "ARCH_BITS is not supported"
+#endif
+        }
+
+        pu++;
+        cBits -= sizeof(size_t) * 8;
+    }
+
+#if ARCH_BITS > 32
+    /* Final 32-bit item (unlikely)? */
+    if (cBits < 32)
+    { }
+    else
+    {
+        uint32_t u32 = *(const volatile uint32_t RT_FAR *)pu;
+        if (u32 != 0)
+        {
+            size_t const iBaseBit = ((uintptr_t)pu - (uintptr_t)pvBitmap) * 8;
+            return iBaseBit + ASMBitFirstSetU32(RT_LE2H_U32(u32)) - 1;
+        }
+    }
+#endif
+
+    return -1;
+}
+