Added new PCM functions (pcm_misc.c).

New plugins: rate, voices.

src/pcm/plugin/rate.c

@@ -0,0 +1,144 @@
+/*
+ *  Rate conversion Plug-In
+ *  Copyright (c) 1999 by Jaroslav Kysela <perex@suse.cz>
+ *
+ *
+ *   This library is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU Library General Public License as
+ *   published by the Free Software Foundation; either version 2 of
+ *   the License, or (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU Library General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Library General Public
+ *   License along with this library; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+  
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <endian.h>
+#include <byteswap.h>
+#include "../pcm_local.h"
+
+/*
+ *  Basic rate conversion plugin
+ */
+ 
+struct rate_private_data {
+	unsigned int src_rate;
+	unsigned int dst_rate;
+	unsigned int pitch;
+	unsigned int pos;
+	signed short last_L_S1, last_R_S1;
+};
+
+static void mix(struct rate_private_data *data,
+	        signed short *src_ptr, int src_size,
+	        signed short *dst_ptr, int dst_size)
+{
+	unsigned int pos;
+	signed int val;
+	signed short L_S1, R_S1, L_S2, R_S2;
+	
+	pos = data->pos;
+	L_S1 = L_S2 = data->last_L_S1;
+	R_S1 = R_S2 = data->last_R_S1;
+	while (dst_size-- > 0) {
+		pos += data->pitch;
+		src_ptr += (pos >> 10) * 2; pos &= 0x3ff;
+		L_S2 = *src_ptr;
+		val = L_S1 + ((L_S2 + L_S1) * (signed int)pos) / 1024;
+		if (val < -32768)
+			val = -32768;
+		else if (val > 32767)
+			val = 32767;
+		*dst_ptr++ = val;
+		R_S2 = *(src_ptr + 1);
+		val = R_S1 + ((R_S2 + R_S1) * (signed int)pos) / 1024;
+		if (val < -32768)
+			val = -32768;
+		else if (val > 32767)
+			val = 32767;
+		*dst_ptr++ = val;
+	}
+	data->last_L_S1 = L_S2;
+	data->last_R_S1 = R_S2;
+	data->pos = pos & 0x3ff;
+}
+
+static ssize_t rate_transfer(snd_pcm_plugin_t *plugin,
+			     char *src_ptr, size_t src_size,
+			     char *dst_ptr, size_t dst_size)
+{
+	struct rate_private_data *data;
+
+	if (plugin == NULL || src_ptr == NULL || src_size < 0 ||
+	                      dst_ptr == NULL || dst_size < 0)
+		return -EINVAL;
+	if (src_size == 0)
+		return 0;
+	data = (struct rate_private_data *)snd_pcm_plugin_extra_data(plugin);
+	if (data == NULL)
+		return -EINVAL;
+	mix(data, (signed short *)src_ptr, src_size / 4,
+		  (signed short *)dst_ptr, dst_size / 4);
+	return (dst_size / 4) * 4;
+}
+
+static ssize_t rate_src_size(snd_pcm_plugin_t *plugin, size_t size)
+{
+	struct rate_private_data *data;
+
+	if (!plugin || size <= 0)
+		return -EINVAL;
+	data = (struct rate_private_data *)snd_pcm_plugin_extra_data(plugin);
+	return (((size * data->pitch) + 0x1ff) >> 10) & ~3;
+}
+
+static ssize_t rate_dst_size(snd_pcm_plugin_t *plugin, size_t size)
+{
+	struct rate_private_data *data;
+
+	if (!plugin || size <= 0)
+		return -EINVAL;
+	data = (struct rate_private_data *)snd_pcm_plugin_extra_data(plugin);
+	return (((size << 10) + (data->pitch / 2)) / data->pitch) & ~3;
+}
+
+int snd_pcm_plugin_build_rate(int src_format, int src_rate, int src_voices,
+			      int dst_format, int dst_rate, int dst_voices,
+			      snd_pcm_plugin_t **r_plugin)
+{
+	struct rate_private_data *data;
+	snd_pcm_plugin_t *plugin;
+
+	if (!r_plugin)
+		return -EINVAL;
+	*r_plugin = NULL;
+	if (src_voices != 2 || dst_voices != 2)
+		return -EINVAL;
+	if (src_format != SND_PCM_SFMT_S16_LE ||
+	    dst_format != SND_PCM_SFMT_S16_LE)
+		return -EINVAL;
+	if (src_rate == dst_rate)
+		return -EINVAL;
+	plugin = snd_pcm_plugin_build("rate format conversion",
+				      sizeof(struct rate_private_data));
+	if (plugin == NULL)
+		return -ENOMEM;
+	data = (struct rate_private_data *)snd_pcm_plugin_extra_data(plugin);
+	data->pitch = ((src_rate << 10) + (dst_rate >> 1)) / dst_rate;
+	plugin->transfer = rate_transfer;
+	plugin->src_size = rate_src_size;
+	plugin->dst_size = rate_dst_size;
+	*r_plugin = plugin;
+	return 0;
+}