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<div class="textblock"><code>#include <sys/types.h></code><br/>
</div>
<p><a href="ringbuffer_8h_source.html">Go to the source code of this file.</a></p>
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Classes</h2></td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">struct  </td><td class="memItemRight" valign="bottom"><a class="el" href="structjack__ringbuffer__data__t.html">jack_ringbuffer_data_t</a></td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">struct  </td><td class="memItemRight" valign="bottom"><a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a></td></tr>
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Functions</h2></td></tr>
<tr class="memitem:a11f9045eb4b0561b26ec434c44e3c922"><td class="memItemLeft" align="right" valign="top"><a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#a11f9045eb4b0561b26ec434c44e3c922">jack_ringbuffer_create</a> (size_t sz)</td></tr>
<tr class="memitem:aa82de39e73e06aa729e092710b83ef61"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#aa82de39e73e06aa729e092710b83ef61">jack_ringbuffer_free</a> (<a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb)</td></tr>
<tr class="memitem:aa21aaf8ff173ba0e89b35554f20d4ccb"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#aa21aaf8ff173ba0e89b35554f20d4ccb">jack_ringbuffer_get_read_vector</a> (const <a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb, <a class="el" href="structjack__ringbuffer__data__t.html">jack_ringbuffer_data_t</a> *vec)</td></tr>
<tr class="memitem:a1c44a50c99f43bb683d8721f14aefc7d"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#a1c44a50c99f43bb683d8721f14aefc7d">jack_ringbuffer_get_write_vector</a> (const <a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb, <a class="el" href="structjack__ringbuffer__data__t.html">jack_ringbuffer_data_t</a> *vec)</td></tr>
<tr class="memitem:a4b001e5844a116a1d51006e2716c73bb"><td class="memItemLeft" align="right" valign="top">size_t </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#a4b001e5844a116a1d51006e2716c73bb">jack_ringbuffer_read</a> (<a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb, char *dest, size_t cnt)</td></tr>
<tr class="memitem:ad268f29e641b39bee8155e7e80ad4520"><td class="memItemLeft" align="right" valign="top">size_t </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#ad268f29e641b39bee8155e7e80ad4520">jack_ringbuffer_peek</a> (<a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb, char *dest, size_t cnt)</td></tr>
<tr class="memitem:aa9cdd4b69ae338c6ce464a1de00ee71a"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#aa9cdd4b69ae338c6ce464a1de00ee71a">jack_ringbuffer_read_advance</a> (<a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb, size_t cnt)</td></tr>
<tr class="memitem:a61e93fa7c9bfb6897dd2508d026d9317"><td class="memItemLeft" align="right" valign="top">size_t </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#a61e93fa7c9bfb6897dd2508d026d9317">jack_ringbuffer_read_space</a> (const <a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb)</td></tr>
<tr class="memitem:aeb059ff23c65389d48ebbe948f05c2b2"><td class="memItemLeft" align="right" valign="top">int </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#aeb059ff23c65389d48ebbe948f05c2b2">jack_ringbuffer_mlock</a> (<a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb)</td></tr>
<tr class="memitem:a40244c7eee331822cd99132a14e76896"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#a40244c7eee331822cd99132a14e76896">jack_ringbuffer_reset</a> (<a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb)</td></tr>
<tr class="memitem:abd4df94d0a2b2ae8bdb98ca1d904402b"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#abd4df94d0a2b2ae8bdb98ca1d904402b">jack_ringbuffer_reset_size</a> (<a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb, size_t sz)</td></tr>
<tr class="memitem:a6d2fc75510e4df62f5b3dd249047b132"><td class="memItemLeft" align="right" valign="top">size_t </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#a6d2fc75510e4df62f5b3dd249047b132">jack_ringbuffer_write</a> (<a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb, const char *src, size_t cnt)</td></tr>
<tr class="memitem:a7255e067e485770d8127d821b6d7e9ec"><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#a7255e067e485770d8127d821b6d7e9ec">jack_ringbuffer_write_advance</a> (<a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb, size_t cnt)</td></tr>
<tr class="memitem:a07a5f6086380300b7b2ccfd7cf9c2ef6"><td class="memItemLeft" align="right" valign="top">size_t </td><td class="memItemRight" valign="bottom"><a class="el" href="ringbuffer_8h.html#a07a5f6086380300b7b2ccfd7cf9c2ef6">jack_ringbuffer_write_space</a> (const <a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> *rb)</td></tr>
</table>
<a name="details" id="details"></a><h2>Detailed Description</h2>
<div class="textblock"><p>A set of library functions to make lock-free ringbuffers available to JACK clients. The `capture_client.c' (in the example_clients directory) is a fully functioning user of this API.</p>
<p>The key attribute of a ringbuffer is that it can be safely accessed by two threads simultaneously – one reading from the buffer and the other writing to it – without using any synchronization or mutual exclusion primitives. For this to work correctly, there can only be a single reader and a single writer thread. Their identities cannot be interchanged. </p>
<p>Definition in file <a class="el" href="ringbuffer_8h_source.html">ringbuffer.h</a>.</p>
</div><h2>Function Documentation</h2>
<a class="anchor" id="a11f9045eb4b0561b26ec434c44e3c922"></a>
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<td class="memname"><a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a>* jack_ringbuffer_create </td>
<td>(</td>
<td class="paramtype">size_t </td>
<td class="paramname"><em>sz</em></td><td>)</td>
<td></td>
</tr>
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<p>Allocates a ringbuffer data structure of a specified size. The caller must arrange for a call to <a class="el" href="ringbuffer_8h.html#aa82de39e73e06aa729e092710b83ef61">jack_ringbuffer_free()</a> to release the memory associated with the ringbuffer.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">sz</td><td>the ringbuffer size in bytes.</td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>a pointer to a new <a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a>, if successful; NULL otherwise. </dd></dl>
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<td class="memname">void jack_ringbuffer_free </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em></td><td>)</td>
<td></td>
</tr>
</table>
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<p>Frees the ringbuffer data structure allocated by an earlier call to <a class="el" href="ringbuffer_8h.html#a11f9045eb4b0561b26ec434c44e3c922">jack_ringbuffer_create()</a>.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure. </td></tr>
</table>
</dd>
</dl>
</div>
</div>
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<td class="memname">void jack_ringbuffer_get_read_vector </td>
<td>(</td>
<td class="paramtype">const <a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="structjack__ringbuffer__data__t.html">jack_ringbuffer_data_t</a> * </td>
<td class="paramname"><em>vec</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
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<p>Fill a data structure with a description of the current readable data held in the ringbuffer. This description is returned in a two element array of <a class="el" href="structjack__ringbuffer__data__t.html">jack_ringbuffer_data_t</a>. Two elements are needed because the data to be read may be split across the end of the ringbuffer.</p>
<p>The first element will always contain a valid <em>len</em> field, which may be zero or greater. If the <em>len</em> field is non-zero, then data can be read in a contiguous fashion using the address given in the corresponding <em>buf</em> field.</p>
<p>If the second element has a non-zero <em>len</em> field, then a second contiguous stretch of data can be read from the address given in its corresponding <em>buf</em> field.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure. </td></tr>
<tr><td class="paramname">vec</td><td>a pointer to a 2 element array of <a class="el" href="structjack__ringbuffer__data__t.html">jack_ringbuffer_data_t</a>. </td></tr>
</table>
</dd>
</dl>
</div>
</div>
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<td class="memname">void jack_ringbuffer_get_write_vector </td>
<td>(</td>
<td class="paramtype">const <a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="structjack__ringbuffer__data__t.html">jack_ringbuffer_data_t</a> * </td>
<td class="paramname"><em>vec</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
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<p>Fill a data structure with a description of the current writable space in the ringbuffer. The description is returned in a two element array of <a class="el" href="structjack__ringbuffer__data__t.html">jack_ringbuffer_data_t</a>. Two elements are needed because the space available for writing may be split across the end of the ringbuffer.</p>
<p>The first element will always contain a valid <em>len</em> field, which may be zero or greater. If the <em>len</em> field is non-zero, then data can be written in a contiguous fashion using the address given in the corresponding <em>buf</em> field.</p>
<p>If the second element has a non-zero <em>len</em> field, then a second contiguous stretch of data can be written to the address given in the corresponding <em>buf</em> field.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure. </td></tr>
<tr><td class="paramname">vec</td><td>a pointer to a 2 element array of <a class="el" href="structjack__ringbuffer__data__t.html">jack_ringbuffer_data_t</a>. </td></tr>
</table>
</dd>
</dl>
</div>
</div>
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<td class="memname">size_t jack_ringbuffer_read </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">char * </td>
<td class="paramname"><em>dest</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">size_t </td>
<td class="paramname"><em>cnt</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
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<p>Read data from the ringbuffer.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure. </td></tr>
<tr><td class="paramname">dest</td><td>a pointer to a buffer where data read from the ringbuffer will go. </td></tr>
<tr><td class="paramname">cnt</td><td>the number of bytes to read.</td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>the number of bytes read, which may range from 0 to cnt. </dd></dl>
</div>
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<td class="memname">size_t jack_ringbuffer_peek </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">char * </td>
<td class="paramname"><em>dest</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">size_t </td>
<td class="paramname"><em>cnt</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
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<p>Read data from the ringbuffer. Opposed to <a class="el" href="ringbuffer_8h.html#a4b001e5844a116a1d51006e2716c73bb">jack_ringbuffer_read()</a> this function does not move the read pointer. Thus it's a convenient way to inspect data in the ringbuffer in a continous fashion. The price is that the data is copied into a user provided buffer. For "raw" non-copy inspection of the data in the ringbuffer use <a class="el" href="ringbuffer_8h.html#aa21aaf8ff173ba0e89b35554f20d4ccb">jack_ringbuffer_get_read_vector()</a>.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure. </td></tr>
<tr><td class="paramname">dest</td><td>a pointer to a buffer where data read from the ringbuffer will go. </td></tr>
<tr><td class="paramname">cnt</td><td>the number of bytes to read.</td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>the number of bytes read, which may range from 0 to cnt. </dd></dl>
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<td class="memname">void jack_ringbuffer_read_advance </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">size_t </td>
<td class="paramname"><em>cnt</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
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<p>Advance the read pointer.</p>
<p>After data have been read from the ringbuffer using the pointers returned by <a class="el" href="ringbuffer_8h.html#aa21aaf8ff173ba0e89b35554f20d4ccb">jack_ringbuffer_get_read_vector()</a>, use this function to advance the buffer pointers, making that space available for future write operations.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure. </td></tr>
<tr><td class="paramname">cnt</td><td>the number of bytes read. </td></tr>
</table>
</dd>
</dl>
</div>
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<td class="memname">size_t jack_ringbuffer_read_space </td>
<td>(</td>
<td class="paramtype">const <a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em></td><td>)</td>
<td></td>
</tr>
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<p>Return the number of bytes available for reading.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure.</td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>the number of bytes available to read. </dd></dl>
</div>
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<td class="memname">int jack_ringbuffer_mlock </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em></td><td>)</td>
<td></td>
</tr>
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<p>Lock a ringbuffer data block into memory.</p>
<p>Uses the mlock() system call. This is not a realtime operation.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure. </td></tr>
</table>
</dd>
</dl>
</div>
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<td class="memname">void jack_ringbuffer_reset </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em></td><td>)</td>
<td></td>
</tr>
</table>
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<p>Reset the read and write pointers, making an empty buffer.</p>
<p>This is not thread safe.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure. </td></tr>
</table>
</dd>
</dl>
</div>
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<td class="memname">void jack_ringbuffer_reset_size </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em>, </td>
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<td></td>
<td class="paramtype">size_t </td>
<td class="paramname"><em>sz</em> </td>
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<p>Reset the internal "available" size, and read and write pointers, making an empty buffer.</p>
<p>This is not thread safe.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure. </td></tr>
<tr><td class="paramname">sz</td><td>the new size, that must be less than allocated size. </td></tr>
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</dd>
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<td class="memname">size_t jack_ringbuffer_write </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em>, </td>
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<td class="paramkey"></td>
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<td class="paramtype">const char * </td>
<td class="paramname"><em>src</em>, </td>
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<td class="paramkey"></td>
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<td class="paramtype">size_t </td>
<td class="paramname"><em>cnt</em> </td>
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<p>Write data into the ringbuffer.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure. </td></tr>
<tr><td class="paramname">src</td><td>a pointer to the data to be written to the ringbuffer. </td></tr>
<tr><td class="paramname">cnt</td><td>the number of bytes to write.</td></tr>
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</dd>
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<dl class="section return"><dt>Returns</dt><dd>the number of bytes write, which may range from 0 to cnt </dd></dl>
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<td class="memname">void jack_ringbuffer_write_advance </td>
<td>(</td>
<td class="paramtype"><a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em>, </td>
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<td class="paramkey"></td>
<td></td>
<td class="paramtype">size_t </td>
<td class="paramname"><em>cnt</em> </td>
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<td>)</td>
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<p>Advance the write pointer.</p>
<p>After data have been written the ringbuffer using the pointers returned by <a class="el" href="ringbuffer_8h.html#a1c44a50c99f43bb683d8721f14aefc7d">jack_ringbuffer_get_write_vector()</a>, use this function to advance the buffer pointer, making the data available for future read operations.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure. </td></tr>
<tr><td class="paramname">cnt</td><td>the number of bytes written. </td></tr>
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</dd>
</dl>
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<td class="memname">size_t jack_ringbuffer_write_space </td>
<td>(</td>
<td class="paramtype">const <a class="el" href="structjack__ringbuffer__t.html">jack_ringbuffer_t</a> * </td>
<td class="paramname"><em>rb</em></td><td>)</td>
<td></td>
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<p>Return the number of bytes available for writing.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">rb</td><td>a pointer to the ringbuffer structure.</td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>the amount of free space (in bytes) available for writing. </dd></dl>
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