teensy-audio/filter_fir.cpp

/* Audio Library for Teensy 3.X
 * Copyright (c) 2014, Pete (El Supremo)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <Arduino.h>
#include "filter_fir.h"


void AudioFilterFIR::update(void)
{
	audio_block_t *block, *b_new;

	block = receiveReadOnly();
	if (!block) return;

	// If there's no coefficient table, give up.  
	if (coeff_p == NULL) {
		release(block);
		return;
	}

	// do passthru
	if (coeff_p == FIR_PASSTHRU) {
		// Just passthrough
		transmit(block);
		release(block);
		return;
	}

	// get a block for the FIR output
	b_new = allocate();
	if (b_new) {
		arm_fir_fast_q15(&fir_inst, (q15_t *)block->data,
			(q15_t *)b_new->data, AUDIO_BLOCK_SAMPLES);
		transmit(b_new); // send the FIR output
		release(b_new);
	}
	release(block);
}