drivers/isdn/mISDN/dsp_audio.c

   1 /*
   2  * Audio support data for mISDN_dsp.
   3  *
   4  * Copyright 2002/2003 by Andreas Eversberg (jolly@eversberg.eu)
   5  * Rewritten by Peter
   6  *
   7  * This software may be used and distributed according to the terms
   8  * of the GNU General Public License, incorporated herein by reference.
   9  *
  10  */
  11
  12 #include <linux/delay.h>
  13 #include <linux/mISDNif.h>
  14 #include <linux/mISDNdsp.h>
  15 #include "core.h"
  16 #include "dsp.h"
  17
  18 /* ulaw[unsigned char] -> signed 16-bit */
  19 s32 dsp_audio_ulaw_to_s32[256];
  20 /* alaw[unsigned char] -> signed 16-bit */
  21 s32 dsp_audio_alaw_to_s32[256];
  22
  23 s32 *dsp_audio_law_to_s32;
  24 EXPORT_SYMBOL(dsp_audio_law_to_s32);
  25
  26 /* signed 16-bit -> law */
  27 u8 dsp_audio_s16_to_law[65536];
  28 EXPORT_SYMBOL(dsp_audio_s16_to_law);
  29
  30 /* alaw -> ulaw */
  31 u8 dsp_audio_alaw_to_ulaw[256];
  32 /* ulaw -> alaw */
  33 static u8 dsp_audio_ulaw_to_alaw[256];
  34 u8 dsp_silence;
  35
  36
  37 /*****************************************************
  38  * generate table for conversion of s16 to alaw/ulaw *
  39  *****************************************************/
  40
  41 #define AMI_MASK 0x55
  42
  43 static inline unsigned char linear2alaw(short int linear)
  44 {
  45         int mask;
  46         int seg;
  47         int pcm_val;
  48         static int seg_end[8] = {
  49                 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF
  50         };
  51
  52         pcm_val = linear;
  53         if (pcm_val >= 0) {
  54                 /* Sign (7th) bit = 1 */
  55                 mask = AMI_MASK | 0x80;
  56         } else {
  57                 /* Sign bit = 0 */
  58                 mask = AMI_MASK;
  59                 pcm_val = -pcm_val;
  60         }
  61
  62         /* Convert the scaled magnitude to segment number. */
  63         for (seg = 0;  seg < 8;  seg++) {
  64                 if (pcm_val <= seg_end[seg])
  65                         break;
  66         }
  67         /* Combine the sign, segment, and quantization bits. */
  68         return  ((seg << 4) |
  69                  ((pcm_val >> ((seg)  ?  (seg + 3)  :  4)) & 0x0F)) ^ mask;
  70 }
  71
  72
  73 static inline short int alaw2linear(unsigned char alaw)
  74 {
  75         int i;
  76         int seg;
  77
  78         alaw ^= AMI_MASK;
  79         i = ((alaw & 0x0F) << 4) + 8 /* rounding error */;
  80         seg = (((int) alaw & 0x70) >> 4);
  81         if (seg)
  82                 i = (i + 0x100) << (seg - 1);
  83         return (short int) ((alaw & 0x80)  ?  i  :  -i);
  84 }
  85
  86 static inline short int ulaw2linear(unsigned char ulaw)
  87 {
  88         short mu, e, f, y;
  89         static short etab[] = {0, 132, 396, 924, 1980, 4092, 8316, 16764};
  90
  91         mu = 255 - ulaw;
  92         e = (mu & 0x70) / 16;
  93         f = mu & 0x0f;
  94         y = f * (1 << (e + 3));
  95         y += etab[e];
  96         if (mu & 0x80)
  97                 y = -y;
  98         return y;
  99 }
 100
 101 #define BIAS 0x84   /*!< define the add-in bias for 16 bit samples */
 102
 103 static unsigned char linear2ulaw(short sample)
 104 {
 105         static int exp_lut[256] = {
 106                 0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
 107                 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
 108                 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
 109                 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
 110                 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
 111                 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
 112                 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
 113                 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
 114                 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
 115                 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
 116                 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
 117                 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
 118                 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
 119                 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
 120                 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
 121                 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7};
 122         int sign, exponent, mantissa;
 123         unsigned char ulawbyte;
 124
 125         /* Get the sample into sign-magnitude. */
 126         sign = (sample >> 8) & 0x80;      /* set aside the sign */
 127         if (sign != 0)
 128                 sample = -sample;             /* get magnitude */
 129
 130         /* Convert from 16 bit linear to ulaw. */
 131         sample = sample + BIAS;
 132         exponent = exp_lut[(sample >> 7) & 0xFF];
 133         mantissa = (sample >> (exponent + 3)) & 0x0F;
 134         ulawbyte = ~(sign | (exponent << 4) | mantissa);
 135
 136         return ulawbyte;
 137 }
 138
 139 static int reverse_bits(int i)
 140 {
 141         int z, j;
 142         z = 0;
 143
 144         for (j = 0; j < 8; j++) {
 145                 if ((i & (1 << j)) != 0)
 146                         z |= 1 << (7 - j);
 147         }
 148         return z;
 149 }
 150
 151
 152 void dsp_audio_generate_law_tables(void)
 153 {
 154         int i;
 155         for (i = 0; i < 256; i++)
 156                 dsp_audio_alaw_to_s32[i] = alaw2linear(reverse_bits(i));
 157
 158         for (i = 0; i < 256; i++)
 159                 dsp_audio_ulaw_to_s32[i] = ulaw2linear(reverse_bits(i));
 160
 161         for (i = 0; i < 256; i++) {
 162                 dsp_audio_alaw_to_ulaw[i] =
 163                         linear2ulaw(dsp_audio_alaw_to_s32[i]);
 164                 dsp_audio_ulaw_to_alaw[i] =
 165                         linear2alaw(dsp_audio_ulaw_to_s32[i]);
 166         }
 167 }
 168
 169 void
 170 dsp_audio_generate_s2law_table(void)
 171 {
 172         int i;
 173
 174         if (dsp_options & DSP_OPT_ULAW) {
 175                 /* generating ulaw-table */
 176                 for (i = -32768; i < 32768; i++) {
 177                         dsp_audio_s16_to_law[i & 0xffff] =
 178                                 reverse_bits(linear2ulaw(i));
 179                 }
 180         } else {
 181                 /* generating alaw-table */
 182                 for (i = -32768; i < 32768; i++) {
 183                         dsp_audio_s16_to_law[i & 0xffff] =
 184                                 reverse_bits(linear2alaw(i));
 185                 }
 186         }
 187 }
 188
 189
 190 /*
 191  * the seven bit sample is the number of every second alaw-sample ordered by
 192  * aplitude. 0x00 is negative, 0x7f is positive amplitude.
 193  */
 194 u8 dsp_audio_seven2law[128];
 195 u8 dsp_audio_law2seven[256];
 196
 197 /********************************************************************
 198  * generate table for conversion law from/to 7-bit alaw-like sample *
 199  ********************************************************************/
 200
 201 void
 202 dsp_audio_generate_seven(void)
 203 {
 204         int i, j, k;
 205         u8 spl;
 206         u8 sorted_alaw[256];
 207
 208         /* generate alaw table, sorted by the linear value */
 209         for (i = 0; i < 256; i++) {
 210                 j = 0;
 211                 for (k = 0; k < 256; k++) {
 212                         if (dsp_audio_alaw_to_s32[k]
 213                             < dsp_audio_alaw_to_s32[i])
 214                                 j++;
 215                 }
 216                 sorted_alaw[j] = i;
 217         }
 218
 219         /* generate tabels */
 220         for (i = 0; i < 256; i++) {
 221                 /* spl is the source: the law-sample (converted to alaw) */
 222                 spl = i;
 223                 if (dsp_options & DSP_OPT_ULAW)
 224                         spl = dsp_audio_ulaw_to_alaw[i];
 225                 /* find the 7-bit-sample */
 226                 for (j = 0; j < 256; j++) {
 227                         if (sorted_alaw[j] == spl)
 228                                 break;
 229                 }
 230                 /* write 7-bit audio value */
 231                 dsp_audio_law2seven[i] = j >> 1;
 232         }
 233         for (i = 0; i < 128; i++) {
 234                 spl = sorted_alaw[i << 1];
 235                 if (dsp_options & DSP_OPT_ULAW)
 236                         spl = dsp_audio_alaw_to_ulaw[spl];
 237                 dsp_audio_seven2law[i] = spl;
 238         }
 239 }
 240
 241
 242 /* mix 2*law -> law */
 243 u8 dsp_audio_mix_law[65536];
 244
 245 /******************************************************
 246  * generate mix table to mix two law samples into one *
 247  ******************************************************/
 248
 249 void
 250 dsp_audio_generate_mix_table(void)
 251 {
 252         int i, j;
 253         s32 sample;
 254
 255         i = 0;
 256         while (i < 256) {
 257                 j = 0;
 258                 while (j < 256) {
 259                         sample = dsp_audio_law_to_s32[i];
 260                         sample += dsp_audio_law_to_s32[j];
 261                         if (sample > 32767)
 262                                 sample = 32767;
 263                         if (sample < -32768)
 264                                 sample = -32768;
 265                         dsp_audio_mix_law[(i<<8)|j] =
 266                                 dsp_audio_s16_to_law[sample & 0xffff];
 267                         j++;
 268                 }
 269                 i++;
 270         }
 271 }
 272
 273
 274 /*************************************
 275  * generate different volume changes *
 276  *************************************/
 277
 278 static u8 dsp_audio_reduce8[256];
 279 static u8 dsp_audio_reduce7[256];
 280 static u8 dsp_audio_reduce6[256];
 281 static u8 dsp_audio_reduce5[256];
 282 static u8 dsp_audio_reduce4[256];
 283 static u8 dsp_audio_reduce3[256];
 284 static u8 dsp_audio_reduce2[256];
 285 static u8 dsp_audio_reduce1[256];
 286 static u8 dsp_audio_increase1[256];
 287 static u8 dsp_audio_increase2[256];
 288 static u8 dsp_audio_increase3[256];
 289 static u8 dsp_audio_increase4[256];
 290 static u8 dsp_audio_increase5[256];
 291 static u8 dsp_audio_increase6[256];
 292 static u8 dsp_audio_increase7[256];
 293 static u8 dsp_audio_increase8[256];
 294
 295 static u8 *dsp_audio_volume_change[16] = {
 296         dsp_audio_reduce8,
 297         dsp_audio_reduce7,
 298         dsp_audio_reduce6,
 299         dsp_audio_reduce5,
 300         dsp_audio_reduce4,
 301         dsp_audio_reduce3,
 302         dsp_audio_reduce2,
 303         dsp_audio_reduce1,
 304         dsp_audio_increase1,
 305         dsp_audio_increase2,
 306         dsp_audio_increase3,
 307         dsp_audio_increase4,
 308         dsp_audio_increase5,
 309         dsp_audio_increase6,
 310         dsp_audio_increase7,
 311         dsp_audio_increase8,
 312 };
 313
 314 void
 315 dsp_audio_generate_volume_changes(void)
 316 {
 317         register s32 sample;
 318         int i;
 319         int num[]   = { 110, 125, 150, 175, 200, 300, 400, 500 };
 320         int denum[] = { 100, 100, 100, 100, 100, 100, 100, 100 };
 321
 322         i = 0;
 323         while (i < 256) {
 324                 dsp_audio_reduce8[i] = dsp_audio_s16_to_law[
 325                         (dsp_audio_law_to_s32[i] * denum[7] / num[7]) & 0xffff];
 326                 dsp_audio_reduce7[i] = dsp_audio_s16_to_law[
 327                         (dsp_audio_law_to_s32[i] * denum[6] / num[6]) & 0xffff];
 328                 dsp_audio_reduce6[i] = dsp_audio_s16_to_law[
 329                         (dsp_audio_law_to_s32[i] * denum[5] / num[5]) & 0xffff];
 330                 dsp_audio_reduce5[i] = dsp_audio_s16_to_law[
 331                         (dsp_audio_law_to_s32[i] * denum[4] / num[4]) & 0xffff];
 332                 dsp_audio_reduce4[i] = dsp_audio_s16_to_law[
 333                         (dsp_audio_law_to_s32[i] * denum[3] / num[3]) & 0xffff];
 334                 dsp_audio_reduce3[i] = dsp_audio_s16_to_law[
 335                         (dsp_audio_law_to_s32[i] * denum[2] / num[2]) & 0xffff];
 336                 dsp_audio_reduce2[i] = dsp_audio_s16_to_law[
 337                         (dsp_audio_law_to_s32[i] * denum[1] / num[1]) & 0xffff];
 338                 dsp_audio_reduce1[i] = dsp_audio_s16_to_law[
 339                         (dsp_audio_law_to_s32[i] * denum[0] / num[0]) & 0xffff];
 340                 sample = dsp_audio_law_to_s32[i] * num[0] / denum[0];
 341                 if (sample < -32768)
 342                         sample = -32768;
 343                 else if (sample > 32767)
 344                         sample = 32767;
 345                 dsp_audio_increase1[i] = dsp_audio_s16_to_law[sample & 0xffff];
 346                 sample = dsp_audio_law_to_s32[i] * num[1] / denum[1];
 347                 if (sample < -32768)
 348                         sample = -32768;
 349                 else if (sample > 32767)
 350                         sample = 32767;
 351                 dsp_audio_increase2[i] = dsp_audio_s16_to_law[sample & 0xffff];
 352                 sample = dsp_audio_law_to_s32[i] * num[2] / denum[2];
 353                 if (sample < -32768)
 354                         sample = -32768;
 355                 else if (sample > 32767)
 356                         sample = 32767;
 357                 dsp_audio_increase3[i] = dsp_audio_s16_to_law[sample & 0xffff];
 358                 sample = dsp_audio_law_to_s32[i] * num[3] / denum[3];
 359                 if (sample < -32768)
 360                         sample = -32768;
 361                 else if (sample > 32767)
 362                         sample = 32767;
 363                 dsp_audio_increase4[i] = dsp_audio_s16_to_law[sample & 0xffff];
 364                 sample = dsp_audio_law_to_s32[i] * num[4] / denum[4];
 365                 if (sample < -32768)
 366                         sample = -32768;
 367                 else if (sample > 32767)
 368                         sample = 32767;
 369                 dsp_audio_increase5[i] = dsp_audio_s16_to_law[sample & 0xffff];
 370                 sample = dsp_audio_law_to_s32[i] * num[5] / denum[5];
 371                 if (sample < -32768)
 372                         sample = -32768;
 373                 else if (sample > 32767)
 374                         sample = 32767;
 375                 dsp_audio_increase6[i] = dsp_audio_s16_to_law[sample & 0xffff];
 376                 sample = dsp_audio_law_to_s32[i] * num[6] / denum[6];
 377                 if (sample < -32768)
 378                         sample = -32768;
 379                 else if (sample > 32767)
 380                         sample = 32767;
 381                 dsp_audio_increase7[i] = dsp_audio_s16_to_law[sample & 0xffff];
 382                 sample = dsp_audio_law_to_s32[i] * num[7] / denum[7];
 383                 if (sample < -32768)
 384                         sample = -32768;
 385                 else if (sample > 32767)
 386                         sample = 32767;
 387                 dsp_audio_increase8[i] = dsp_audio_s16_to_law[sample & 0xffff];
 388
 389                 i++;
 390         }
 391 }
 392
 393
 394 /**************************************
 395  * change the volume of the given skb *
 396  **************************************/
 397
 398 /* this is a helper function for changing volume of skb. the range may be
 399  * -8 to 8, which is a shift to the power of 2. 0 == no volume, 3 == volume*8
 400  */
 401 void
 402 dsp_change_volume(struct sk_buff *skb, int volume)
 403 {
 404         u8 *volume_change;
 405         int i, ii;
 406         u8 *p;
 407         int shift;
 408
 409         if (volume == 0)
 410                 return;
 411
 412         /* get correct conversion table */
 413         if (volume < 0) {
 414                 shift = volume + 8;
 415                 if (shift < 0)
 416                         shift = 0;
 417         } else {
 418                 shift = volume + 7;
 419                 if (shift > 15)
 420                         shift = 15;
 421         }
 422         volume_change = dsp_audio_volume_change[shift];
 423         i = 0;
 424         ii = skb->len;
 425         p = skb->data;
 426         /* change volume */
 427         while (i < ii) {
 428                 *p = volume_change[*p];
 429                 p++;
 430                 i++;
 431         }
 432 }
 433