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Next: <a href="Bytevectors.html" accesskey="n" rel="next">Bytevectors</a>, Previous: <a href="Vectors.html" accesskey="p" rel="prev">Vectors</a>, Up: <a href="Data-Types.html" accesskey="u" rel="up">Data Types</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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<h4 class="subsection" id="Bit-Vectors-1"><span>6.6.11 Bit Vectors<a class="copiable-link" href="#Bit-Vectors-1"> &para;</a></span></h4>
<p>Bit vectors are zero-origin, one-dimensional arrays of booleans. They
are displayed as a sequence of <code class="code">0</code>s and <code class="code">1</code>s prefixed by
<code class="code">#*</code>, e.g.,
</p>
<div class="example">
<pre class="example-preformatted">(make-bitvector 8 #f) &rArr;
#*00000000
</pre></div>
<p>Bit vectors are the special case of one dimensional bit arrays, and can
thus be used with the array procedures, See <a class="xref" href="Arrays.html">Arrays</a>.
</p>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector_003f"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector?</strong> <var class="def-var-arguments">obj</var><a class="copiable-link" href="#index-bitvector_003f"> &para;</a></span></dt>
<dd><p>Return <code class="code">#t</code> when <var class="var">obj</var> is a bitvector, else
return <code class="code">#f</code>.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-make_002dbitvector"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">make-bitvector</strong> <var class="def-var-arguments">len [fill]</var><a class="copiable-link" href="#index-make_002dbitvector"> &para;</a></span></dt>
<dd><p>Create a new bitvector of length <var class="var">len</var> and
optionally initialize all elements to <var class="var">fill</var>.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector</strong> <var class="def-var-arguments">bit &hellip;</var><a class="copiable-link" href="#index-bitvector"> &para;</a></span></dt>
<dd><p>Create a new bitvector with the arguments as elements.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector_002dlength"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-length</strong> <var class="def-var-arguments">vec</var><a class="copiable-link" href="#index-bitvector_002dlength"> &para;</a></span></dt>
<dd><p>Return the length of the bitvector <var class="var">vec</var>.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector_002dbit_002dset_003f"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-bit-set?</strong> <var class="def-var-arguments">vec idx</var><a class="copiable-link" href="#index-bitvector_002dbit_002dset_003f"> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-bitvector_002dbit_002dclear_003f"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-bit-clear?</strong> <var class="def-var-arguments">vec idx</var><a class="copiable-link" href="#index-bitvector_002dbit_002dclear_003f"> &para;</a></span></dt>
<dd><p>Return <code class="code">#t</code> if the bit at index <var class="var">idx</var> of the bitvector
<var class="var">vec</var> is set (for <code class="code">bitvector-bit-set?</code>) or clear (for
<code class="code">bitvector-bit-clear?</code>).
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector_002dset_002dbit_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-set-bit!</strong> <var class="def-var-arguments">vec idx</var><a class="copiable-link" href="#index-bitvector_002dset_002dbit_0021"> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-bitvector_002dclear_002dbit_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-clear-bit!</strong> <var class="def-var-arguments">vec idx</var><a class="copiable-link" href="#index-bitvector_002dclear_002dbit_0021"> &para;</a></span></dt>
<dd><p>Set (for <code class="code">bitvector-set-bit!</code>) or clear (for
<code class="code">bitvector-clear-bit!</code>) the bit at index <var class="var">idx</var> of the bitvector
<var class="var">vec</var>.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector_002dset_002dall_002dbits_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-set-all-bits!</strong> <var class="def-var-arguments">vec</var><a class="copiable-link" href="#index-bitvector_002dset_002dall_002dbits_0021"> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-bitvector_002dclear_002dall_002dbits_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-clear-all-bits!</strong> <var class="def-var-arguments">vec</var><a class="copiable-link" href="#index-bitvector_002dclear_002dall_002dbits_0021"> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-bitvector_002dflip_002dall_002dbits_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-flip-all-bits!</strong> <var class="def-var-arguments">vec</var><a class="copiable-link" href="#index-bitvector_002dflip_002dall_002dbits_0021"> &para;</a></span></dt>
<dd><p>Set, clear, or flip all bits of <var class="var">vec</var>.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-list_002d_003ebitvector"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">list-&gt;bitvector</strong> <var class="def-var-arguments">list</var><a class="copiable-link" href="#index-list_002d_003ebitvector"> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-scm_005flist_005fto_005fbitvector"><span class="category-def">C Function: </span><span><strong class="def-name">scm_list_to_bitvector</strong> <var class="def-var-arguments">(list)</var><a class="copiable-link" href="#index-scm_005flist_005fto_005fbitvector"> &para;</a></span></dt>
<dd><p>Return a new bitvector initialized with the elements
of <var class="var">list</var>.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector_002d_003elist"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-&gt;list</strong> <var class="def-var-arguments">vec</var><a class="copiable-link" href="#index-bitvector_002d_003elist"> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-scm_005fbitvector_005fto_005flist"><span class="category-def">C Function: </span><span><strong class="def-name">scm_bitvector_to_list</strong> <var class="def-var-arguments">(vec)</var><a class="copiable-link" href="#index-scm_005fbitvector_005fto_005flist"> &para;</a></span></dt>
<dd><p>Return a new list initialized with the elements
of the bitvector <var class="var">vec</var>.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector_002dcopy"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-copy</strong> <var class="def-var-arguments">bitvector [start [end]]</var><a class="copiable-link" href="#index-bitvector_002dcopy"> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-scm_005fbitvector_005fcopy"><span class="category-def">C Function: </span><span><strong class="def-name">scm_bitvector_copy</strong> <var class="def-var-arguments">(bitvector, start, end)</var><a class="copiable-link" href="#index-scm_005fbitvector_005fcopy"> &para;</a></span></dt>
<dd><p>Returns a freshly allocated bitvector containing the elements of <var class="var">bitvector</var>
in the range [<var class="var">start</var> ... <var class="var">end</var>). <var class="var">start</var> defaults to 0 and
<var class="var">end</var> defaults to the length of <var class="var">bitvector</var>.
</p></dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector_002dcount"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-count</strong> <var class="def-var-arguments">bitvector</var><a class="copiable-link" href="#index-bitvector_002dcount"> &para;</a></span></dt>
<dd><p>Return a count of how many entries in <var class="var">bitvector</var> are set.
</p>
<div class="example">
<pre class="example-preformatted">(bitvector-count #*000111000) &rArr; 3
</pre></div>
</dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector_002dcount_002dbits"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-count-bits</strong> <var class="def-var-arguments">bitvector bits</var><a class="copiable-link" href="#index-bitvector_002dcount_002dbits"> &para;</a></span></dt>
<dd><p>Return a count of how many entries in <var class="var">bitvector</var> are set, with the
bitvector <var class="var">bits</var> selecting the entries to consider. <var class="var">bitvector</var>
must be at least as long as <var class="var">bits</var>.
</p>
<p>For example,
</p>
<div class="example">
<pre class="example-preformatted">(bitvector-count-bits #*01110111 #*11001101) &rArr; 3
</pre></div>
</dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector_002dposition"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-position</strong> <var class="def-var-arguments">bitvector bool start</var><a class="copiable-link" href="#index-bitvector_002dposition"> &para;</a></span></dt>
<dt class="deffnx def-cmd-deffn" id="index-scm_005fbitvector_005fposition"><span class="category-def">C Function: </span><span><strong class="def-name">scm_bitvector_position</strong> <var class="def-var-arguments">(bitvector, bool, start)</var><a class="copiable-link" href="#index-scm_005fbitvector_005fposition"> &para;</a></span></dt>
<dd><p>Return the index of the first occurrence of <var class="var">bool</var> in
<var class="var">bitvector</var>, starting from <var class="var">start</var>. If there is no <var class="var">bool</var>
entry between <var class="var">start</var> and the end of <var class="var">bitvector</var>, then return
<code class="code">#f</code>. For example,
</p>
<div class="example">
<pre class="example-preformatted">(bitvector-position #*000101 #t 0) &rArr; 3
(bitvector-position #*0001111 #f 3) &rArr; #f
</pre></div>
</dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector_002dset_002dbits_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-set-bits!</strong> <var class="def-var-arguments">bitvector bits</var><a class="copiable-link" href="#index-bitvector_002dset_002dbits_0021"> &para;</a></span></dt>
<dd><p>Set entries of <var class="var">bitvector</var> to <code class="code">#t</code>, with <var class="var">bits</var> selecting
the bits to set. The return value is unspecified. <var class="var">bitvector</var> must
be at least as long as <var class="var">bits</var>.
</p>
<div class="example">
<pre class="example-preformatted">(define bv (bitvector-copy #*11000010))
(bitvector-set-bits! bv #*10010001)
bv
&rArr; #*11010011
</pre></div>
</dd></dl>
<dl class="first-deffn">
<dt class="deffn" id="index-bitvector_002dclear_002dbits_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">bitvector-clear-bits!</strong> <var class="def-var-arguments">bitvector bits</var><a class="copiable-link" href="#index-bitvector_002dclear_002dbits_0021"> &para;</a></span></dt>
<dd><p>Set entries of <var class="var">bitvector</var> to <code class="code">#f</code>, with <var class="var">bits</var> selecting
the bits to clear. The return value is unspecified. <var class="var">bitvector</var>
must be at least as long as <var class="var">bits</var>.
</p>
<div class="example">
<pre class="example-preformatted">(define bv (bitvector-copy #*11000010))
(bitvector-clear-bits! bv #*10010001)
bv
&rArr; #*01000010
</pre></div>
</dd></dl>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-scm_005fis_005fbitvector"><span class="category-def">C Function: </span><span><code class="def-type">int</code> <strong class="def-name">scm_is_bitvector</strong> <code class="def-code-arguments">(SCM obj)</code><a class="copiable-link" href="#index-scm_005fis_005fbitvector"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fc_005fmake_005fbitvector"><span class="category-def">C Function: </span><span><code class="def-type">SCM</code> <strong class="def-name">scm_c_make_bitvector</strong> <code class="def-code-arguments">(size_t len, SCM fill)</code><a class="copiable-link" href="#index-scm_005fc_005fmake_005fbitvector"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fbitvector_005fbit_005fis_005fset"><span class="category-def">C Function: </span><span><code class="def-type">int</code> <strong class="def-name">scm_bitvector_bit_is_set</strong> <code class="def-code-arguments">(SCM vec, size_t idx)</code><a class="copiable-link" href="#index-scm_005fbitvector_005fbit_005fis_005fset"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fbitvector_005fbit_005fis_005fclear"><span class="category-def">C Function: </span><span><code class="def-type">int</code> <strong class="def-name">scm_bitvector_bit_is_clear</strong> <code class="def-code-arguments">(SCM vec, size_t idx)</code><a class="copiable-link" href="#index-scm_005fbitvector_005fbit_005fis_005fclear"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fc_005fbitvector_005fset_005fbit_005fx"><span class="category-def">C Function: </span><span><code class="def-type">void</code> <strong class="def-name">scm_c_bitvector_set_bit_x</strong> <code class="def-code-arguments">(SCM vec, size_t idx)</code><a class="copiable-link" href="#index-scm_005fc_005fbitvector_005fset_005fbit_005fx"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fc_005fbitvector_005fclear_005fbit_005fx"><span class="category-def">C Function: </span><span><code class="def-type">void</code> <strong class="def-name">scm_c_bitvector_clear_bit_x</strong> <code class="def-code-arguments">(SCM vec, size_t idx)</code><a class="copiable-link" href="#index-scm_005fc_005fbitvector_005fclear_005fbit_005fx"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fc_005fbitvector_005fset_005fbits_005fx"><span class="category-def">C Function: </span><span><code class="def-type">void</code> <strong class="def-name">scm_c_bitvector_set_bits_x</strong> <code class="def-code-arguments">(SCM vec, SCM bits)</code><a class="copiable-link" href="#index-scm_005fc_005fbitvector_005fset_005fbits_005fx"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fc_005fbitvector_005fclear_005fbits_005fx"><span class="category-def">C Function: </span><span><code class="def-type">void</code> <strong class="def-name">scm_c_bitvector_clear_bits_x</strong> <code class="def-code-arguments">(SCM vec, SCM bits)</code><a class="copiable-link" href="#index-scm_005fc_005fbitvector_005fclear_005fbits_005fx"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fc_005fbitvector_005fset_005fall_005fbits_005fx"><span class="category-def">C Function: </span><span><code class="def-type">void</code> <strong class="def-name">scm_c_bitvector_set_all_bits_x</strong> <code class="def-code-arguments">(SCM vec)</code><a class="copiable-link" href="#index-scm_005fc_005fbitvector_005fset_005fall_005fbits_005fx"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fc_005fbitvector_005fclear_005fall_005fbits_005fx"><span class="category-def">C Function: </span><span><code class="def-type">void</code> <strong class="def-name">scm_c_bitvector_clear_all_bits_x</strong> <code class="def-code-arguments">(SCM vec)</code><a class="copiable-link" href="#index-scm_005fc_005fbitvector_005fclear_005fall_005fbits_005fx"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fc_005fbitvector_005fflip_005fall_005fbits_005fx"><span class="category-def">C Function: </span><span><code class="def-type">void</code> <strong class="def-name">scm_c_bitvector_flip_all_bits_x</strong> <code class="def-code-arguments">(SCM vec)</code><a class="copiable-link" href="#index-scm_005fc_005fbitvector_005fflip_005fall_005fbits_005fx"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fc_005fbitvector_005flength"><span class="category-def">C Function: </span><span><code class="def-type">size_t</code> <strong class="def-name">scm_c_bitvector_length</strong> <code class="def-code-arguments">(SCM bitvector)</code><a class="copiable-link" href="#index-scm_005fc_005fbitvector_005flength"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fc_005fbitvector_005fcount"><span class="category-def">C Function: </span><span><code class="def-type">size_t</code> <strong class="def-name">scm_c_bitvector_count</strong> <code class="def-code-arguments">(SCM bitvector)</code><a class="copiable-link" href="#index-scm_005fc_005fbitvector_005fcount"> &para;</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-scm_005fc_005fbitvector_005fcount_005fbits"><span class="category-def">C Function: </span><span><code class="def-type">size_t</code> <strong class="def-name">scm_c_bitvector_count_bits</strong> <code class="def-code-arguments">(SCM bitvector, SCM bits)</code><a class="copiable-link" href="#index-scm_005fc_005fbitvector_005fcount_005fbits"> &para;</a></span></dt>
<dd><p>C API for the corresponding Scheme bitvector interfaces.
</p></dd></dl>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-scm_005fbitvector_005felements"><span class="category-def">C Function: </span><span><code class="def-type">const scm_t_uint32 *</code> <strong class="def-name">scm_bitvector_elements</strong> <code class="def-code-arguments">(SCM vec, scm_t_array_handle *handle, size_t *offp, size_t *lenp, ssize_t *incp)</code><a class="copiable-link" href="#index-scm_005fbitvector_005felements"> &para;</a></span></dt>
<dd><p>Like <code class="code">scm_vector_elements</code> (see <a class="pxref" href="Vector-Accessing-from-C.html">Vector Accessing from C</a>), but
for bitvectors. The variable pointed to by <var class="var">offp</var> is set to the
value returned by <code class="code">scm_array_handle_bit_elements_offset</code>. See
<code class="code">scm_array_handle_bit_elements</code> for how to use the returned
pointer and the offset.
</p></dd></dl>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-scm_005fbitvector_005fwritable_005felements"><span class="category-def">C Function: </span><span><code class="def-type">scm_t_uint32 *</code> <strong class="def-name">scm_bitvector_writable_elements</strong> <code class="def-code-arguments">(SCM vec, scm_t_array_handle *handle, size_t *offp, size_t *lenp, ssize_t *incp)</code><a class="copiable-link" href="#index-scm_005fbitvector_005fwritable_005felements"> &para;</a></span></dt>
<dd><p>Like <code class="code">scm_bitvector_elements</code>, but the pointer is good for reading
and writing.
</p></dd></dl>
</div>
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