forked from luck/tmp_suning_uos_patched
fea952e5cc
Change the core code where sparse complains. In most cases, this means just adding annotations to confirm that we indeed want to do the dirty things we're doing. Signed-off-by: Clemens Ladisch <clemens@ladisch.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>
345 lines
10 KiB
C
345 lines
10 KiB
C
/*
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* Mu-Law conversion Plug-In Interface
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* Copyright (c) 1999 by Jaroslav Kysela <perex@perex.cz>
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* Uros Bizjak <uros@kss-loka.si>
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*
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* Based on reference implementation by Sun Microsystems, Inc.
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Library General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <linux/time.h>
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#include <sound/core.h>
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#include <sound/pcm.h>
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#include "pcm_plugin.h"
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#define SIGN_BIT (0x80) /* Sign bit for a u-law byte. */
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#define QUANT_MASK (0xf) /* Quantization field mask. */
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#define NSEGS (8) /* Number of u-law segments. */
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#define SEG_SHIFT (4) /* Left shift for segment number. */
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#define SEG_MASK (0x70) /* Segment field mask. */
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static inline int val_seg(int val)
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{
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int r = 0;
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val >>= 7;
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if (val & 0xf0) {
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val >>= 4;
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r += 4;
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}
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if (val & 0x0c) {
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val >>= 2;
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r += 2;
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}
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if (val & 0x02)
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r += 1;
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return r;
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}
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#define BIAS (0x84) /* Bias for linear code. */
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/*
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* linear2ulaw() - Convert a linear PCM value to u-law
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*
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* In order to simplify the encoding process, the original linear magnitude
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* is biased by adding 33 which shifts the encoding range from (0 - 8158) to
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* (33 - 8191). The result can be seen in the following encoding table:
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*
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* Biased Linear Input Code Compressed Code
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* ------------------------ ---------------
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* 00000001wxyza 000wxyz
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* 0000001wxyzab 001wxyz
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* 000001wxyzabc 010wxyz
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* 00001wxyzabcd 011wxyz
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* 0001wxyzabcde 100wxyz
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* 001wxyzabcdef 101wxyz
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* 01wxyzabcdefg 110wxyz
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* 1wxyzabcdefgh 111wxyz
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*
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* Each biased linear code has a leading 1 which identifies the segment
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* number. The value of the segment number is equal to 7 minus the number
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* of leading 0's. The quantization interval is directly available as the
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* four bits wxyz. * The trailing bits (a - h) are ignored.
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*
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* Ordinarily the complement of the resulting code word is used for
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* transmission, and so the code word is complemented before it is returned.
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*
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* For further information see John C. Bellamy's Digital Telephony, 1982,
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* John Wiley & Sons, pps 98-111 and 472-476.
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*/
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static unsigned char linear2ulaw(int pcm_val) /* 2's complement (16-bit range) */
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{
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int mask;
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int seg;
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unsigned char uval;
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/* Get the sign and the magnitude of the value. */
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if (pcm_val < 0) {
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pcm_val = BIAS - pcm_val;
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mask = 0x7F;
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} else {
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pcm_val += BIAS;
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mask = 0xFF;
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}
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if (pcm_val > 0x7FFF)
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pcm_val = 0x7FFF;
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/* Convert the scaled magnitude to segment number. */
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seg = val_seg(pcm_val);
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/*
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* Combine the sign, segment, quantization bits;
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* and complement the code word.
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*/
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uval = (seg << 4) | ((pcm_val >> (seg + 3)) & 0xF);
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return uval ^ mask;
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}
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/*
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* ulaw2linear() - Convert a u-law value to 16-bit linear PCM
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*
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* First, a biased linear code is derived from the code word. An unbiased
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* output can then be obtained by subtracting 33 from the biased code.
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*
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* Note that this function expects to be passed the complement of the
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* original code word. This is in keeping with ISDN conventions.
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*/
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static int ulaw2linear(unsigned char u_val)
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{
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int t;
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/* Complement to obtain normal u-law value. */
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u_val = ~u_val;
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/*
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* Extract and bias the quantization bits. Then
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* shift up by the segment number and subtract out the bias.
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*/
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t = ((u_val & QUANT_MASK) << 3) + BIAS;
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t <<= ((unsigned)u_val & SEG_MASK) >> SEG_SHIFT;
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return ((u_val & SIGN_BIT) ? (BIAS - t) : (t - BIAS));
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}
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/*
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* Basic Mu-Law plugin
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*/
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typedef void (*mulaw_f)(struct snd_pcm_plugin *plugin,
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const struct snd_pcm_plugin_channel *src_channels,
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struct snd_pcm_plugin_channel *dst_channels,
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snd_pcm_uframes_t frames);
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struct mulaw_priv {
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mulaw_f func;
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int cvt_endian; /* need endian conversion? */
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unsigned int native_ofs; /* byte offset in native format */
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unsigned int copy_ofs; /* byte offset in s16 format */
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unsigned int native_bytes; /* byte size of the native format */
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unsigned int copy_bytes; /* bytes to copy per conversion */
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u16 flip; /* MSB flip for signedness, done after endian conversion */
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};
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static inline void cvt_s16_to_native(struct mulaw_priv *data,
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unsigned char *dst, u16 sample)
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{
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sample ^= data->flip;
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if (data->cvt_endian)
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sample = swab16(sample);
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if (data->native_bytes > data->copy_bytes)
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memset(dst, 0, data->native_bytes);
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memcpy(dst + data->native_ofs, (char *)&sample + data->copy_ofs,
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data->copy_bytes);
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}
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static void mulaw_decode(struct snd_pcm_plugin *plugin,
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const struct snd_pcm_plugin_channel *src_channels,
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struct snd_pcm_plugin_channel *dst_channels,
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snd_pcm_uframes_t frames)
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{
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struct mulaw_priv *data = (struct mulaw_priv *)plugin->extra_data;
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int channel;
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int nchannels = plugin->src_format.channels;
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for (channel = 0; channel < nchannels; ++channel) {
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char *src;
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char *dst;
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int src_step, dst_step;
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snd_pcm_uframes_t frames1;
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if (!src_channels[channel].enabled) {
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if (dst_channels[channel].wanted)
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snd_pcm_area_silence(&dst_channels[channel].area, 0, frames, plugin->dst_format.format);
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dst_channels[channel].enabled = 0;
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continue;
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}
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dst_channels[channel].enabled = 1;
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src = src_channels[channel].area.addr + src_channels[channel].area.first / 8;
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dst = dst_channels[channel].area.addr + dst_channels[channel].area.first / 8;
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src_step = src_channels[channel].area.step / 8;
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dst_step = dst_channels[channel].area.step / 8;
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frames1 = frames;
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while (frames1-- > 0) {
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signed short sample = ulaw2linear(*src);
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cvt_s16_to_native(data, dst, sample);
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src += src_step;
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dst += dst_step;
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}
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}
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}
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static inline signed short cvt_native_to_s16(struct mulaw_priv *data,
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unsigned char *src)
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{
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u16 sample = 0;
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memcpy((char *)&sample + data->copy_ofs, src + data->native_ofs,
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data->copy_bytes);
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if (data->cvt_endian)
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sample = swab16(sample);
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sample ^= data->flip;
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return (signed short)sample;
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}
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static void mulaw_encode(struct snd_pcm_plugin *plugin,
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const struct snd_pcm_plugin_channel *src_channels,
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struct snd_pcm_plugin_channel *dst_channels,
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snd_pcm_uframes_t frames)
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{
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struct mulaw_priv *data = (struct mulaw_priv *)plugin->extra_data;
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int channel;
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int nchannels = plugin->src_format.channels;
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for (channel = 0; channel < nchannels; ++channel) {
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char *src;
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char *dst;
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int src_step, dst_step;
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snd_pcm_uframes_t frames1;
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if (!src_channels[channel].enabled) {
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if (dst_channels[channel].wanted)
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snd_pcm_area_silence(&dst_channels[channel].area, 0, frames, plugin->dst_format.format);
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dst_channels[channel].enabled = 0;
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continue;
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}
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dst_channels[channel].enabled = 1;
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src = src_channels[channel].area.addr + src_channels[channel].area.first / 8;
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dst = dst_channels[channel].area.addr + dst_channels[channel].area.first / 8;
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src_step = src_channels[channel].area.step / 8;
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dst_step = dst_channels[channel].area.step / 8;
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frames1 = frames;
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while (frames1-- > 0) {
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signed short sample = cvt_native_to_s16(data, src);
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*dst = linear2ulaw(sample);
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src += src_step;
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dst += dst_step;
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}
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}
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}
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static snd_pcm_sframes_t mulaw_transfer(struct snd_pcm_plugin *plugin,
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const struct snd_pcm_plugin_channel *src_channels,
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struct snd_pcm_plugin_channel *dst_channels,
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snd_pcm_uframes_t frames)
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{
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struct mulaw_priv *data;
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if (snd_BUG_ON(!plugin || !src_channels || !dst_channels))
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return -ENXIO;
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if (frames == 0)
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return 0;
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#ifdef CONFIG_SND_DEBUG
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{
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unsigned int channel;
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for (channel = 0; channel < plugin->src_format.channels; channel++) {
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if (snd_BUG_ON(src_channels[channel].area.first % 8 ||
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src_channels[channel].area.step % 8))
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return -ENXIO;
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if (snd_BUG_ON(dst_channels[channel].area.first % 8 ||
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dst_channels[channel].area.step % 8))
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return -ENXIO;
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}
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}
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#endif
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data = (struct mulaw_priv *)plugin->extra_data;
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data->func(plugin, src_channels, dst_channels, frames);
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return frames;
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}
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static void init_data(struct mulaw_priv *data, snd_pcm_format_t format)
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{
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#ifdef SNDRV_LITTLE_ENDIAN
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data->cvt_endian = snd_pcm_format_big_endian(format) > 0;
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#else
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data->cvt_endian = snd_pcm_format_little_endian(format) > 0;
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#endif
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if (!snd_pcm_format_signed(format))
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data->flip = 0x8000;
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data->native_bytes = snd_pcm_format_physical_width(format) / 8;
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data->copy_bytes = data->native_bytes < 2 ? 1 : 2;
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if (snd_pcm_format_little_endian(format)) {
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data->native_ofs = data->native_bytes - data->copy_bytes;
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data->copy_ofs = 2 - data->copy_bytes;
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} else {
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/* S24 in 4bytes need an 1 byte offset */
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data->native_ofs = data->native_bytes -
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snd_pcm_format_width(format) / 8;
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}
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}
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int snd_pcm_plugin_build_mulaw(struct snd_pcm_substream *plug,
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struct snd_pcm_plugin_format *src_format,
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struct snd_pcm_plugin_format *dst_format,
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struct snd_pcm_plugin **r_plugin)
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{
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int err;
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struct mulaw_priv *data;
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struct snd_pcm_plugin *plugin;
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struct snd_pcm_plugin_format *format;
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mulaw_f func;
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if (snd_BUG_ON(!r_plugin))
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return -ENXIO;
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*r_plugin = NULL;
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if (snd_BUG_ON(src_format->rate != dst_format->rate))
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return -ENXIO;
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if (snd_BUG_ON(src_format->channels != dst_format->channels))
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return -ENXIO;
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if (dst_format->format == SNDRV_PCM_FORMAT_MU_LAW) {
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format = src_format;
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func = mulaw_encode;
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}
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else if (src_format->format == SNDRV_PCM_FORMAT_MU_LAW) {
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format = dst_format;
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func = mulaw_decode;
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}
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else {
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snd_BUG();
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return -EINVAL;
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}
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if (snd_BUG_ON(!snd_pcm_format_linear(format->format)))
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return -ENXIO;
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err = snd_pcm_plugin_build(plug, "Mu-Law<->linear conversion",
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src_format, dst_format,
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sizeof(struct mulaw_priv), &plugin);
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if (err < 0)
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return err;
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data = (struct mulaw_priv *)plugin->extra_data;
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data->func = func;
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init_data(data, format->format);
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plugin->transfer = mulaw_transfer;
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*r_plugin = plugin;
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return 0;
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}
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