'\" t
.\"     Title: bitmap_remap
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: July 2017
.\"    Manual: Basic Kernel Library Functions
.\"    Source: Kernel Hackers Manual 4.11.6
.\"  Language: English
.\"
.TH "BITMAP_REMAP" "9" "July 2017" "Kernel Hackers Manual 4\&.11\&" "Basic Kernel Library Functions"
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.SH "NAME"
bitmap_remap \- Apply map defined by a pair of bitmaps to another bitmap
.SH "SYNOPSIS"
.HP \w'void\ bitmap_remap('u
.BI "void bitmap_remap(unsigned\ long\ *\ " "dst" ", const\ unsigned\ long\ *\ " "src" ", const\ unsigned\ long\ *\ " "old" ", const\ unsigned\ long\ *\ " "new" ", unsigned\ int\ " "nbits" ");"
.SH "ARGUMENTS"
.PP
\fIunsigned long * dst\fR
.RS 4
remapped result
.RE
.PP
\fIconst unsigned long * src\fR
.RS 4
subset to be remapped
.RE
.PP
\fIconst unsigned long * old\fR
.RS 4
defines domain of map
.RE
.PP
\fIconst unsigned long * new\fR
.RS 4
defines range of map
.RE
.PP
\fIunsigned int nbits\fR
.RS 4
number of bits in each of these bitmaps
.RE
.SH "DESCRIPTION"
.PP
Let
\fIold\fR
and
\fInew\fR
define a mapping of bit positions, such that whatever position is held by the n\-th set bit in
\fIold\fR
is mapped to the n\-th set bit in
\fInew\fR\&. In the more general case, allowing for the possibility that the weight \*(Aqw\*(Aq of
\fInew\fR
is less than the weight of
\fIold\fR, map the position of the n\-th set bit in
\fIold\fR
to the position of the m\-th set bit in
\fInew\fR, where m == n % w\&.
.PP
If either of the
\fIold\fR
and
\fInew\fR
bitmaps are empty, or if
\fIsrc\fR
and
\fIdst\fR
point to the same location, then this routine copies
\fIsrc\fR
to
\fIdst\fR\&.
.PP
The positions of unset bits in
\fIold\fR
are mapped to themselves (the identify map)\&.
.PP
Apply the above specified mapping to
\fIsrc\fR, placing the result in
\fIdst\fR, clearing any bits previously set in
\fIdst\fR\&.
.PP
For example, lets say that
\fIold\fR
has bits 4 through 7 set, and
\fInew\fR
has bits 12 through 15 set\&. This defines the mapping of bit position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other bit positions unchanged\&. So if say
\fIsrc\fR
comes into this routine with bits 1, 5 and 7 set, then
\fIdst\fR
should leave with bits 1, 13 and 15 set\&.
.SH "COPYRIGHT"
.br