41b2885d0903c5e93d14cc425fc6ae6dcefec3c6
[linux-2.6.git] / sound / core / oss / linear.c
1 /*
2  *  Linear conversion Plug-In
3  *  Copyright (c) 1999 by Jaroslav Kysela <perex@suse.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 <sound/driver.h>
24 #include <linux/time.h>
25 #include <sound/core.h>
26 #include <sound/pcm.h>
27 #include "pcm_plugin.h"
28
29 /*
30  *  Basic linear conversion plugin
31  */
32  
33 struct linear_priv {
34         int cvt_endian;         /* need endian conversion? */
35         unsigned int src_ofs;   /* byte offset in source format */
36         unsigned int dst_ofs;   /* byte soffset in destination format */
37         unsigned int copy_ofs;  /* byte offset in temporary u32 data */
38         unsigned int dst_bytes;         /* byte size of destination format */
39         unsigned int copy_bytes;        /* bytes to copy per conversion */
40         unsigned int flip; /* MSB flip for signeness, done after endian conv */
41 };
42
43 static inline void do_convert(struct linear_priv *data,
44                               unsigned char *dst, unsigned char *src)
45 {
46         unsigned int tmp = 0;
47         unsigned char *p = (unsigned char *)&tmp;
48
49         memcpy(p + data->copy_ofs, src + data->src_ofs, data->copy_bytes);
50         if (data->cvt_endian)
51                 tmp = swab32(tmp);
52         tmp ^= data->flip;
53         memcpy(dst, p + data->dst_ofs, data->dst_bytes);
54 }
55
56 static void convert(struct snd_pcm_plugin *plugin,
57                     const struct snd_pcm_plugin_channel *src_channels,
58                     struct snd_pcm_plugin_channel *dst_channels,
59                     snd_pcm_uframes_t frames)
60 {
61         struct linear_priv *data = (struct linear_priv *)plugin->extra_data;
62         int channel;
63         int nchannels = plugin->src_format.channels;
64         for (channel = 0; channel < nchannels; ++channel) {
65                 char *src;
66                 char *dst;
67                 int src_step, dst_step;
68                 snd_pcm_uframes_t frames1;
69                 if (!src_channels[channel].enabled) {
70                         if (dst_channels[channel].wanted)
71                                 snd_pcm_area_silence(&dst_channels[channel].area, 0, frames, plugin->dst_format.format);
72                         dst_channels[channel].enabled = 0;
73                         continue;
74                 }
75                 dst_channels[channel].enabled = 1;
76                 src = src_channels[channel].area.addr + src_channels[channel].area.first / 8;
77                 dst = dst_channels[channel].area.addr + dst_channels[channel].area.first / 8;
78                 src_step = src_channels[channel].area.step / 8;
79                 dst_step = dst_channels[channel].area.step / 8;
80                 frames1 = frames;
81                 while (frames1-- > 0) {
82                         do_convert(data, dst, src);
83                         src += src_step;
84                         dst += dst_step;
85                 }
86         }
87 }
88
89 static snd_pcm_sframes_t linear_transfer(struct snd_pcm_plugin *plugin,
90                                const struct snd_pcm_plugin_channel *src_channels,
91                                struct snd_pcm_plugin_channel *dst_channels,
92                                snd_pcm_uframes_t frames)
93 {
94         struct linear_priv *data;
95
96         snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, 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                         snd_assert(src_channels[channel].area.first % 8 == 0 &&
105                                    src_channels[channel].area.step % 8 == 0,
106                                    return -ENXIO);
107                         snd_assert(dst_channels[channel].area.first % 8 == 0 &&
108                                    dst_channels[channel].area.step % 8 == 0,
109                                    return -ENXIO);
110                 }
111         }
112 #endif
113         convert(plugin, src_channels, dst_channels, frames);
114         return frames;
115 }
116
117 static void init_data(struct linear_priv *data, int src_format, int dst_format)
118 {
119         int src_le, dst_le, src_bytes, dst_bytes;
120
121         src_bytes = snd_pcm_format_width(src_format) / 8;
122         dst_bytes = snd_pcm_format_width(dst_format) / 8;
123         src_le = snd_pcm_format_little_endian(src_format) > 0;
124         dst_le = snd_pcm_format_little_endian(dst_format) > 0;
125
126         data->dst_bytes = dst_bytes;
127         data->cvt_endian = src_le != dst_le;
128         data->copy_bytes = src_bytes < dst_bytes ? src_bytes : dst_bytes;
129         if (src_le) {
130                 data->copy_ofs = 4 - data->copy_bytes;
131                 data->src_ofs = src_bytes - data->copy_bytes;
132         } else
133                 data->src_ofs = snd_pcm_format_physical_width(src_format) / 8 -
134                         src_bytes;
135         if (dst_le)
136                 data->dst_ofs = 4 - data->dst_bytes;
137         else
138                 data->dst_ofs = snd_pcm_format_physical_width(dst_format) / 8 -
139                         dst_bytes;
140         if (snd_pcm_format_signed(src_format) !=
141             snd_pcm_format_signed(dst_format)) {
142                 if (dst_le)
143                         data->flip = cpu_to_le32(0x80000000);
144                 else
145                         data->flip = cpu_to_be32(0x80000000);
146         }
147 }
148
149 int snd_pcm_plugin_build_linear(struct snd_pcm_substream *plug,
150                                 struct snd_pcm_plugin_format *src_format,
151                                 struct snd_pcm_plugin_format *dst_format,
152                                 struct snd_pcm_plugin **r_plugin)
153 {
154         int err;
155         struct linear_priv *data;
156         struct snd_pcm_plugin *plugin;
157
158         snd_assert(r_plugin != NULL, return -ENXIO);
159         *r_plugin = NULL;
160
161         snd_assert(src_format->rate == dst_format->rate, return -ENXIO);
162         snd_assert(src_format->channels == dst_format->channels, return -ENXIO);
163         snd_assert(snd_pcm_format_linear(src_format->format) &&
164                    snd_pcm_format_linear(dst_format->format), return -ENXIO);
165
166         err = snd_pcm_plugin_build(plug, "linear format conversion",
167                                    src_format, dst_format,
168                                    sizeof(struct linear_priv), &plugin);
169         if (err < 0)
170                 return err;
171         data = (struct linear_priv *)plugin->extra_data;
172         init_data(data, src_format->format, dst_format->format);
173         plugin->transfer = linear_transfer;
174         *r_plugin = plugin;
175         return 0;
176 }