comb_1190.xml

<?xml version="1.0" ?>
<!DOCTYPE ladspa SYSTEM "ladspa-swh.dtd">
<?xml-stylesheet href="ladspa.css" type="text/css" ?>
<ladspa>
	<global>
		<meta name="maker" value="Steve Harris &lt;steve@plugin.org.uk&gt;"/>
		<meta name="copyright" value="GPL"/>
		<meta name="properties" value="HARD_RT_CAPABLE"/>
		<code>
			#include "ladspa-util.h"
			#define COMB_SIZE 0x4000
			#define COMB_MASK 0x3FFF
		</code>
	</global>

	<plugin label="comb" id="1190" class="CombPlugin">
		<name>Comb Filter</name>

		<callback event="instantiate">
			sample_rate = s_rate;
			comb_tbl = malloc(sizeof(LADSPA_Data) * COMB_SIZE);
			comb_pos = 0;
			last_offset = 1000;
		</callback>

		<callback event="activate">
			int i;

			for (i = 0; i &lt; COMB_SIZE; i++) {
				comb_tbl[i] = 0;
			}
			comb_pos = 0;
			last_offset = 1000;
		</callback>

		<callback event="cleanup">
			free(plugin_data->comb_tbl);
		</callback>

		<callback event="run"><![CDATA[
			float offset;
			int data_pos;
			unsigned long pos;
			float xf, xf_step, d_pos, fr, interp;

			offset = sample_rate / freq;
			offset = f_clamp(offset, 0, COMB_SIZE - 1);
			xf_step = 1.0f / (float)sample_count;
			xf = 0.0f;

			for (pos = 0; pos < sample_count; pos++) {
				xf += xf_step;
				d_pos = comb_pos - LIN_INTERP(xf, last_offset, offset);
				data_pos = f_trunc(d_pos);
				fr = d_pos - data_pos;
				interp =  cube_interp(fr, comb_tbl[(data_pos - 1) & COMB_MASK], comb_tbl[data_pos & COMB_MASK], comb_tbl[(data_pos + 1) & COMB_MASK], comb_tbl[(data_pos + 2) & COMB_MASK]);
				comb_tbl[comb_pos] = input[pos] + fb * interp;
				buffer_write(output[pos], (input[pos] + interp) * 0.5f);
				comb_pos = (comb_pos + 1) & COMB_MASK;
			}

			plugin_data->comb_pos = comb_pos;
			plugin_data->last_offset = offset;
		]]></callback>

		<port label="freq" dir="input" type="control" hint="default_low">
			<name>Band separation (Hz)</name>
			<range min="16" max="640"/>
			<p>Controls the distance between the filters peaks.</p>
		</port>

		<port label="fb" dir="input" type="control" hint="default_0">
			<name>Feedback</name>
			<range min="-0.99" max="0.99"/>
			<p>Feedback level, increases the distinctive wooshy phaser sound.</p>
		</port>

		<port label="input" dir="input" type="audio">
			<name>Input</name>
		</port>

		<port label="output" dir="output" type="audio">
			<name>Output</name>
		</port>

		<instance-data label="comb_tbl" type="LADSPA_Data *"/>
		<instance-data label="comb_pos" type="long"/>
		<instance-data label="sample_rate" type="long"/>
		<instance-data label="last_offset" type="float"/>
	</plugin>
</ladspa>