1 /*
2 * Linear conversion Plug-In
3 * Copyright (c) 1999 by Jaroslav Kysela <perex@perex.cz>,
4 * Abramo Bagnara <abramo@alsa-project.org>
5 *
6 *
7 * This library is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU Library General Public License as
9 * published by the Free Software Foundation; either version 2 of
10 * the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU Library General Public License for more details.
16 *
17 * You should have received a copy of the GNU Library General Public
18 * License along with this library; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 *
21 */
22
23 #include <linux/time.h>
24 #include <sound/core.h>
25 #include <sound/pcm.h>
26 #include "pcm_plugin.h"
27
28 /*
29 * Basic linear conversion plugin
30 */
31
32 struct linear_priv {
33 int cvt_endian; /* need endian conversion? */
34 unsigned int src_ofs; /* byte offset in source format */
35 unsigned int dst_ofs; /* byte soffset in destination format */
36 unsigned int copy_ofs; /* byte offset in temporary u32 data */
37 unsigned int dst_bytes; /* byte size of destination format */
38 unsigned int copy_bytes; /* bytes to copy per conversion */
39 unsigned int flip; /* MSB flip for signeness, done after endian conv */
40 };
41
do_convert(struct linear_priv * data,unsigned char * dst,unsigned char * src)42 static inline void do_convert(struct linear_priv *data,
43 unsigned char *dst, unsigned char *src)
44 {
45 unsigned int tmp = 0;
46 unsigned char *p = (unsigned char *)&tmp;
47
48 memcpy(p + data->copy_ofs, src + data->src_ofs, data->copy_bytes);
49 if (data->cvt_endian)
50 tmp = swab32(tmp);
51 tmp ^= data->flip;
52 memcpy(dst, p + data->dst_ofs, data->dst_bytes);
53 }
54
convert(struct snd_pcm_plugin * plugin,const struct snd_pcm_plugin_channel * src_channels,struct snd_pcm_plugin_channel * dst_channels,snd_pcm_uframes_t frames)55 static void convert(struct snd_pcm_plugin *plugin,
56 const struct snd_pcm_plugin_channel *src_channels,
57 struct snd_pcm_plugin_channel *dst_channels,
58 snd_pcm_uframes_t frames)
59 {
60 struct linear_priv *data = (struct linear_priv *)plugin->extra_data;
61 int channel;
62 int nchannels = plugin->src_format.channels;
63 for (channel = 0; channel < nchannels; ++channel) {
64 char *src;
65 char *dst;
66 int src_step, dst_step;
67 snd_pcm_uframes_t frames1;
68 if (!src_channels[channel].enabled) {
69 if (dst_channels[channel].wanted)
70 snd_pcm_area_silence(&dst_channels[channel].area, 0, frames, plugin->dst_format.format);
71 dst_channels[channel].enabled = 0;
72 continue;
73 }
74 dst_channels[channel].enabled = 1;
75 src = src_channels[channel].area.addr + src_channels[channel].area.first / 8;
76 dst = dst_channels[channel].area.addr + dst_channels[channel].area.first / 8;
77 src_step = src_channels[channel].area.step / 8;
78 dst_step = dst_channels[channel].area.step / 8;
79 frames1 = frames;
80 while (frames1-- > 0) {
81 do_convert(data, dst, src);
82 src += src_step;
83 dst += dst_step;
84 }
85 }
86 }
87
linear_transfer(struct snd_pcm_plugin * plugin,const struct snd_pcm_plugin_channel * src_channels,struct snd_pcm_plugin_channel * dst_channels,snd_pcm_uframes_t frames)88 static snd_pcm_sframes_t linear_transfer(struct snd_pcm_plugin *plugin,
89 const struct snd_pcm_plugin_channel *src_channels,
90 struct snd_pcm_plugin_channel *dst_channels,
91 snd_pcm_uframes_t frames)
92 {
93 struct linear_priv *data;
94
95 if (snd_BUG_ON(!plugin || !src_channels || !dst_channels))
96 return -ENXIO;
97 data = (struct linear_priv *)plugin->extra_data;
98 if (frames == 0)
99 return 0;
100 #ifdef CONFIG_SND_DEBUG
101 {
102 unsigned int channel;
103 for (channel = 0; channel < plugin->src_format.channels; channel++) {
104 if (snd_BUG_ON(src_channels[channel].area.first % 8 ||
105 src_channels[channel].area.step % 8))
106 return -ENXIO;
107 if (snd_BUG_ON(dst_channels[channel].area.first % 8 ||
108 dst_channels[channel].area.step % 8))
109 return -ENXIO;
110 }
111 }
112 #endif
113 convert(plugin, src_channels, dst_channels, frames);
114 return frames;
115 }
116
init_data(struct linear_priv * data,snd_pcm_format_t src_format,snd_pcm_format_t dst_format)117 static void init_data(struct linear_priv *data,
118 snd_pcm_format_t src_format, snd_pcm_format_t dst_format)
119 {
120 int src_le, dst_le, src_bytes, dst_bytes;
121
122 src_bytes = snd_pcm_format_width(src_format) / 8;
123 dst_bytes = snd_pcm_format_width(dst_format) / 8;
124 src_le = snd_pcm_format_little_endian(src_format) > 0;
125 dst_le = snd_pcm_format_little_endian(dst_format) > 0;
126
127 data->dst_bytes = dst_bytes;
128 data->cvt_endian = src_le != dst_le;
129 data->copy_bytes = src_bytes < dst_bytes ? src_bytes : dst_bytes;
130 if (src_le) {
131 data->copy_ofs = 4 - data->copy_bytes;
132 data->src_ofs = src_bytes - data->copy_bytes;
133 } else
134 data->src_ofs = snd_pcm_format_physical_width(src_format) / 8 -
135 src_bytes;
136 if (dst_le)
137 data->dst_ofs = 4 - data->dst_bytes;
138 else
139 data->dst_ofs = snd_pcm_format_physical_width(dst_format) / 8 -
140 dst_bytes;
141 if (snd_pcm_format_signed(src_format) !=
142 snd_pcm_format_signed(dst_format)) {
143 if (dst_le)
144 data->flip = (__force u32)cpu_to_le32(0x80000000);
145 else
146 data->flip = (__force u32)cpu_to_be32(0x80000000);
147 }
148 }
149
snd_pcm_plugin_build_linear(struct snd_pcm_substream * plug,struct snd_pcm_plugin_format * src_format,struct snd_pcm_plugin_format * dst_format,struct snd_pcm_plugin ** r_plugin)150 int snd_pcm_plugin_build_linear(struct snd_pcm_substream *plug,
151 struct snd_pcm_plugin_format *src_format,
152 struct snd_pcm_plugin_format *dst_format,
153 struct snd_pcm_plugin **r_plugin)
154 {
155 int err;
156 struct linear_priv *data;
157 struct snd_pcm_plugin *plugin;
158
159 if (snd_BUG_ON(!r_plugin))
160 return -ENXIO;
161 *r_plugin = NULL;
162
163 if (snd_BUG_ON(src_format->rate != dst_format->rate))
164 return -ENXIO;
165 if (snd_BUG_ON(src_format->channels != dst_format->channels))
166 return -ENXIO;
167 if (snd_BUG_ON(!snd_pcm_format_linear(src_format->format) ||
168 !snd_pcm_format_linear(dst_format->format)))
169 return -ENXIO;
170
171 err = snd_pcm_plugin_build(plug, "linear format conversion",
172 src_format, dst_format,
173 sizeof(struct linear_priv), &plugin);
174 if (err < 0)
175 return err;
176 data = (struct linear_priv *)plugin->extra_data;
177 init_data(data, src_format->format, dst_format->format);
178 plugin->transfer = linear_transfer;
179 *r_plugin = plugin;
180 return 0;
181 }
182