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+.\"
+.\" This file and its contents are supplied under the terms of the
+.\" Common Development and Distribution License ("CDDL"), version 1.0.
+.\" You may only use this file in accordance with the terms of version
+.\" 1.0 of the CDDL.
+.\"
+.\" A full copy of the text of the CDDL should have accompanied this
+.\" source.  A copy of the CDDL is also available via the Internet at
+.\" http://www.illumos.org/license/CDDL.
+.\"
+.\"
+.\" Copyright 2022 Oxide Computer Company
+.\"
+.Dd April 12, 2022
+.Dt BITDEL64 9F
+.Os
+.Sh NAME
+.Nm bitdel64
+.Nd delete bits from an integer
+.Sh SYNOPSIS
+.In sys/bitext.h
+.Ft uint64_t
+.Fo bitdel64
+.Fa "uint64_t value"
+.Fa "uint_t high"
+.Fa "uint_t low"
+.Fc
+.Sh INTERFACE LEVEL
+.Sy Volatile -
+This interface is still evolving in illumos.
+API and ABI stability is not guaranteed.
+.Sh PARAMETERS
+.Bl -tag -width Fa
+.It Fa value
+.It Fa high
+The high end, inclusive, of the bit range to delete from
+.Fa value .
+.It Fa low
+The low end, inclusive, of the bit range to delete from
+.Fa value .
+.It Fa value
+An integer to remove bits from.
+.El
+.Sh DESCRIPTION
+The
+.Fn bitdel64
+function removes bits from an integer,
+.Fa value .
+The act of removing a bit range not only removes all the bits in the
+range specified by
+.Fa low
+and
+.Fa high ,
+but also causes all remaining bits to be shifted over to start at
+.Fa low .
+.Pp
+For example, consider the binary value 0b11_1101_0011
+.Pq 0x3d3 .
+If we deleted bits 4 through 7, the resulting value would be 0b11_0011
+.Pq 0x33 .
+.Pp
+.Fa high
+and
+.Fa low
+are an inclusive range
+.Po
+.Pf [ Fa low ,
+.Fa high ]
+.Pc
+and the value of
+.Fa low
+cannot be greater than
+.Fa high
+or 63.
+.Sh RETURN VALUES
+Upon successful completion, the
+.Fn bitdel64
+returns the modified integer with the appropriate bits removed.
+.Sh SEE ALSO
+.Xr bitset64 9F ,
+.Xr bitx64 9F