Index: sys/sys/gauges.h
===================================================================
--- /dev/null
+++ sys/sys/gauges.h
@@ -0,0 +1,116 @@
+/*-
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 1982, 1986, 1991, 1993, 1994
+ *	The Regents of the University of California.  All rights reserved.
+ * (c) UNIX System Laboratories, Inc.
+ * All or some portions of this file are derived from material licensed
+ * to the University of California by American Telephone and Telegraph
+ * Co. or Unix System Laboratories, Inc. and are reproduced herein with
+ * the permission of UNIX System Laboratories, Inc.
+ *
+ * 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.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ *
+ *	@(#)gauges.h	8.6 (Berkeley) 2/19/95
+ * $FreeBSD$
+ */
+
+#ifndef _SYS_GAUGES_H_
+#define	_SYS_GAUGES_H_
+
+/* Machine type dependent parameters. */
+#include <machine/endian.h>
+
+#if __BSD_VISIBLE
+
+typedef	uint8_t		gauge8_t;
+typedef	uint16_t	gauge16_t;
+typedef	uint32_t	gauge32_t;
+typedef	uint64_t	gauge64_t;
+
+#endif
+
+/*
+ * The following are all things that  provide miscellaneous doodads.
+ */
+
+#if __BSD_VISIBLE
+/*
+ * Programmatically determine the maximum value of
+ * a signed or unsigned type, without integer overflow.
+ * Determining if the type of a variable is signed
+ * or not in a portable way without typeof() is quite
+ * involved but the resuting code is still optimal.
+ */
+#define UTYPE_MAX(x) \
+	((((1 << (sizeof((x)) * 8 - 1)) - 1) * 2) + 1)
+#define TYPE_MAX(x) \
+	((((1 << (sizeof((x)) * 8 - 2)) - 1) * 2) + 1)
+
+/*
+ * Macro to Post-increment gauges that should NOT
+ * overflow, as a drop-in replacement for 'x++'.
+ */
+#define CEILINC(x) \
+	((x) < UTYPE_MAX(x)) ? (x)++ : (x)
+
+/*
+ * Macro to Pre-increment gauges that should NOT
+ * overflow, as a drop-in replacement for '++x'.
+ */
+#define INCCEIL(x) \
+	((x) < UTYPE_MAX(x)) ? ++(x) : (x)
+
+/*
+ * Macro to Post-decrement gauges that should NOT
+ * underflow, as a drop-in replacement for 'x--'.
+ */
+#define FLOORDEC(x) \
+	((x) > 0) ? (x)-- : (x)
+
+/*
+ * Macro to Pre-decrement gauges that should NOT
+ * underflow, as a drop-in replacement for '--x'.
+ */
+#define DECFLOOR(x) \
+	((x) > 0) ? --(x) : (x)
+
+/*
+ * Macro to increment gauges that should NOT
+ * overflow, as a drop-in replacement for 'x+var'.
+ */
+#define ADDCEIL(x,v) \
+	((x) <= (UTYPE_MAX(x)-(v)) ? (x)+(v) : UTYPE_MAX(x)
+
+/*
+ * Macro to decrement gauges that should NOT
+ * underflow, as a drop-in replacement for 'x-var'.
+ */
+#define SUBFLOOR(x,v) \
+	((x) >= (v)) ? (x)-(v) : 0
+
+#endif /* __BSD_VISIBLE */
+
+#endif /* !_SYS_GAUGES_H_ */