96 lines
2.2 KiB
C
96 lines
2.2 KiB
C
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/*
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* PCM DRM helpers
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/export.h>
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#include <linux/types.h>
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#include <sound/asoundef.h>
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#include <sound/pcm.h>
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#include <sound/pcm_iec958.h>
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/**
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* snd_pcm_create_iec958_consumer - create consumer format IEC958 channel status
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* @runtime: pcm runtime structure with ->rate filled in
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* @cs: channel status buffer, at least four bytes
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* @len: length of channel status buffer
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*
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* Create the consumer format channel status data in @cs of maximum size
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* @len corresponding to the parameters of the PCM runtime @runtime.
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*
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* Drivers may wish to tweak the contents of the buffer after creation.
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*
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* Returns: length of buffer, or negative error code if something failed.
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*/
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int snd_pcm_create_iec958_consumer(struct snd_pcm_runtime *runtime, u8 *cs,
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size_t len)
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{
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unsigned int fs, ws;
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if (len < 4)
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return -EINVAL;
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switch (runtime->rate) {
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case 32000:
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fs = IEC958_AES3_CON_FS_32000;
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break;
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case 44100:
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fs = IEC958_AES3_CON_FS_44100;
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break;
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case 48000:
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fs = IEC958_AES3_CON_FS_48000;
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break;
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case 88200:
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fs = IEC958_AES3_CON_FS_88200;
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break;
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case 96000:
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fs = IEC958_AES3_CON_FS_96000;
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break;
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case 176400:
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fs = IEC958_AES3_CON_FS_176400;
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break;
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case 192000:
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fs = IEC958_AES3_CON_FS_192000;
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break;
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default:
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return -EINVAL;
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}
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if (len > 4) {
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switch (snd_pcm_format_width(runtime->format)) {
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case 16:
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ws = IEC958_AES4_CON_WORDLEN_20_16;
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break;
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case 18:
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ws = IEC958_AES4_CON_WORDLEN_22_18;
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break;
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case 20:
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ws = IEC958_AES4_CON_WORDLEN_20_16 |
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IEC958_AES4_CON_MAX_WORDLEN_24;
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break;
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case 24:
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ws = IEC958_AES4_CON_WORDLEN_24_20 |
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IEC958_AES4_CON_MAX_WORDLEN_24;
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break;
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default:
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return -EINVAL;
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}
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}
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memset(cs, 0, len);
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cs[0] = IEC958_AES0_CON_NOT_COPYRIGHT | IEC958_AES0_CON_EMPHASIS_NONE;
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cs[1] = IEC958_AES1_CON_GENERAL;
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cs[2] = IEC958_AES2_CON_SOURCE_UNSPEC | IEC958_AES2_CON_CHANNEL_UNSPEC;
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cs[3] = IEC958_AES3_CON_CLOCK_1000PPM | fs;
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if (len > 4)
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cs[4] = ws;
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return len;
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}
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EXPORT_SYMBOL(snd_pcm_create_iec958_consumer);
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