xref: /openbmc/linux/sound/core/oss/linear.c (revision 4cc8d650)
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 	if (snd_BUG_ON(!plugin || !src_channels || !dst_channels))
94 		return -ENXIO;
95 	if (frames == 0)
96 		return 0;
97 #ifdef CONFIG_SND_DEBUG
98 	{
99 		unsigned int channel;
100 		for (channel = 0; channel < plugin->src_format.channels; channel++) {
101 			if (snd_BUG_ON(src_channels[channel].area.first % 8 ||
102 				       src_channels[channel].area.step % 8))
103 				return -ENXIO;
104 			if (snd_BUG_ON(dst_channels[channel].area.first % 8 ||
105 				       dst_channels[channel].area.step % 8))
106 				return -ENXIO;
107 		}
108 	}
109 #endif
110 	if (frames > dst_channels[0].frames)
111 		frames = dst_channels[0].frames;
112 	convert(plugin, src_channels, dst_channels, frames);
113 	return frames;
114 }
115 
init_data(struct linear_priv * data,snd_pcm_format_t src_format,snd_pcm_format_t dst_format)116 static void init_data(struct linear_priv *data,
117 		      snd_pcm_format_t src_format, snd_pcm_format_t 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 = (__force u32)cpu_to_le32(0x80000000);
144 		else
145 			data->flip = (__force u32)cpu_to_be32(0x80000000);
146 	}
147 }
148 
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)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 	if (snd_BUG_ON(!r_plugin))
159 		return -ENXIO;
160 	*r_plugin = NULL;
161 
162 	if (snd_BUG_ON(src_format->rate != dst_format->rate))
163 		return -ENXIO;
164 	if (snd_BUG_ON(src_format->channels != dst_format->channels))
165 		return -ENXIO;
166 	if (snd_BUG_ON(!snd_pcm_format_linear(src_format->format) ||
167 		       !snd_pcm_format_linear(dst_format->format)))
168 		return -ENXIO;
169 
170 	err = snd_pcm_plugin_build(plug, "linear format conversion",
171 				   src_format, dst_format,
172 				   sizeof(struct linear_priv), &plugin);
173 	if (err < 0)
174 		return err;
175 	data = (struct linear_priv *)plugin->extra_data;
176 	init_data(data, src_format->format, dst_format->format);
177 	plugin->transfer = linear_transfer;
178 	*r_plugin = plugin;
179 	return 0;
180 }
181