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                 }
 217                 sorted_alaw[j] = i;
 218         }
 219
 220         /* generate tabels */
 221         for (i = 0; i < 256; i++) {
 222                 /* spl is the source: the law-sample (converted to alaw) */
 223                 spl = i;
 224                 if (dsp_options & DSP_OPT_ULAW)
 225                         spl = dsp_audio_ulaw_to_alaw[i];
 226                 /* find the 7-bit-sample */
 227                 for (j = 0; j < 256; j++) {
 228                         if (sorted_alaw[j] == spl)
 229                                 break;
 230                 }
 231                 /* write 7-bit audio value */
 232                 dsp_audio_law2seven[i] = j >> 1;
 233         }
 234         for (i = 0; i < 128; i++) {
 235                 spl = sorted_alaw[i << 1];
 236                 if (dsp_options & DSP_OPT_ULAW)
 237                         spl = dsp_audio_alaw_to_ulaw[spl];
 238                 dsp_audio_seven2law[i] = spl;
 239         }
 240 }
 241
 242
 243 /* mix 2*law -> law */
 244 u8 dsp_audio_mix_law[65536];
 245
 246 /******************************************************
 247  * generate mix table to mix two law samples into one *
 248  ******************************************************/
 249
 250 void
 251 dsp_audio_generate_mix_table(void)
 252 {
 253         int i, j;
 254         s32 sample;
 255
 256         i = 0;
 257         while (i < 256) {
 258                 j = 0;
 259                 while (j < 256) {
 260                         sample = dsp_audio_law_to_s32[i];
 261                         sample += dsp_audio_law_to_s32[j];
 262                         if (sample > 32767)
 263                                 sample = 32767;
 264                         if (sample < -32768)
 265                                 sample = -32768;
 266                         dsp_audio_mix_law[(i<<8)|j] =
 267                                 dsp_audio_s16_to_law[sample & 0xffff];
 268                         j++;
 269                 }
 270                 i++;
 271         }
 272 }
 273
 274
 275 /*************************************
 276  * generate different volume changes *
 277  *************************************/
 278
 279 static u8 dsp_audio_reduce8[256];
 280 static u8 dsp_audio_reduce7[256];
 281 static u8 dsp_audio_reduce6[256];
 282 static u8 dsp_audio_reduce5[256];
 283 static u8 dsp_audio_reduce4[256];
 284 static u8 dsp_audio_reduce3[256];
 285 static u8 dsp_audio_reduce2[256];
 286 static u8 dsp_audio_reduce1[256];
 287 static u8 dsp_audio_increase1[256];
 288 static u8 dsp_audio_increase2[256];
 289 static u8 dsp_audio_increase3[256];
 290 static u8 dsp_audio_increase4[256];
 291 static u8 dsp_audio_increase5[256];
 292 static u8 dsp_audio_increase6[256];
 293 static u8 dsp_audio_increase7[256];
 294 static u8 dsp_audio_increase8[256];
 295
 296 static u8 *dsp_audio_volume_change[16] = {
 297         dsp_audio_reduce8,
 298         dsp_audio_reduce7,
 299         dsp_audio_reduce6,
 300         dsp_audio_reduce5,
 301         dsp_audio_reduce4,
 302         dsp_audio_reduce3,
 303         dsp_audio_reduce2,
 304         dsp_audio_reduce1,
 305         dsp_audio_increase1,
 306         dsp_audio_increase2,
 307         dsp_audio_increase3,
 308         dsp_audio_increase4,
 309         dsp_audio_increase5,
 310         dsp_audio_increase6,
 311         dsp_audio_increase7,
 312         dsp_audio_increase8,
 313 };
 314
 315 void
 316 dsp_audio_generate_volume_changes(void)
 317 {
 318         register s32 sample;
 319         int i;
 320         int num[]   = { 110, 125, 150, 175, 200, 300, 400, 500 };
 321         int denum[] = { 100, 100, 100, 100, 100, 100, 100, 100 };
 322
 323         i = 0;
 324         while (i < 256) {
 325                 dsp_audio_reduce8[i] = dsp_audio_s16_to_law[
 326                         (dsp_audio_law_to_s32[i] * denum[7] / num[7]) & 0xffff];
 327                 dsp_audio_reduce7[i] = dsp_audio_s16_to_law[
 328                         (dsp_audio_law_to_s32[i] * denum[6] / num[6]) & 0xffff];
 329                 dsp_audio_reduce6[i] = dsp_audio_s16_to_law[
 330                         (dsp_audio_law_to_s32[i] * denum[5] / num[5]) & 0xffff];
 331                 dsp_audio_reduce5[i] = dsp_audio_s16_to_law[
 332                         (dsp_audio_law_to_s32[i] * denum[4] / num[4]) & 0xffff];
 333                 dsp_audio_reduce4[i] = dsp_audio_s16_to_law[
 334                         (dsp_audio_law_to_s32[i] * denum[3] / num[3]) & 0xffff];
 335                 dsp_audio_reduce3[i] = dsp_audio_s16_to_law[
 336                         (dsp_audio_law_to_s32[i] * denum[2] / num[2]) & 0xffff];
 337                 dsp_audio_reduce2[i] = dsp_audio_s16_to_law[
 338                         (dsp_audio_law_to_s32[i] * denum[1] / num[1]) & 0xffff];
 339                 dsp_audio_reduce1[i] = dsp_audio_s16_to_law[
 340                         (dsp_audio_law_to_s32[i] * denum[0] / num[0]) & 0xffff];
 341                 sample = dsp_audio_law_to_s32[i] * num[0] / denum[0];
 342                 if (sample < -32768)
 343                         sample = -32768;
 344                 else if (sample > 32767)
 345                         sample = 32767;
 346                 dsp_audio_increase1[i] = dsp_audio_s16_to_law[sample & 0xffff];
 347                 sample = dsp_audio_law_to_s32[i] * num[1] / denum[1];
 348                 if (sample < -32768)
 349                         sample = -32768;
 350                 else if (sample > 32767)
 351                         sample = 32767;
 352                 dsp_audio_increase2[i] = dsp_audio_s16_to_law[sample & 0xffff];
 353                 sample = dsp_audio_law_to_s32[i] * num[2] / denum[2];
 354                 if (sample < -32768)
 355                         sample = -32768;
 356                 else if (sample > 32767)
 357                         sample = 32767;
 358                 dsp_audio_increase3[i] = dsp_audio_s16_to_law[sample & 0xffff];
 359                 sample = dsp_audio_law_to_s32[i] * num[3] / denum[3];
 360                 if (sample < -32768)
 361                         sample = -32768;
 362                 else if (sample > 32767)
 363                         sample = 32767;
 364                 dsp_audio_increase4[i] = dsp_audio_s16_to_law[sample & 0xffff];
 365                 sample = dsp_audio_law_to_s32[i] * num[4] / denum[4];
 366                 if (sample < -32768)
 367                         sample = -32768;
 368                 else if (sample > 32767)
 369                         sample = 32767;
 370                 dsp_audio_increase5[i] = dsp_audio_s16_to_law[sample & 0xffff];
 371                 sample = dsp_audio_law_to_s32[i] * num[5] / denum[5];
 372                 if (sample < -32768)
 373                         sample = -32768;
 374                 else if (sample > 32767)
 375                         sample = 32767;
 376                 dsp_audio_increase6[i] = dsp_audio_s16_to_law[sample & 0xffff];
 377                 sample = dsp_audio_law_to_s32[i] * num[6] / denum[6];
 378                 if (sample < -32768)
 379                         sample = -32768;
 380                 else if (sample > 32767)
 381                         sample = 32767;
 382                 dsp_audio_increase7[i] = dsp_audio_s16_to_law[sample & 0xffff];
 383                 sample = dsp_audio_law_to_s32[i] * num[7] / denum[7];
 384                 if (sample < -32768)
 385                         sample = -32768;
 386                 else if (sample > 32767)
 387                         sample = 32767;
 388                 dsp_audio_increase8[i] = dsp_audio_s16_to_law[sample & 0xffff];
 389
 390                 i++;
 391         }
 392 }
 393
 394
 395 /**************************************
 396  * change the volume of the given skb *
 397  **************************************/
 398
 399 /* this is a helper function for changing volume of skb. the range may be
 400  * -8 to 8, which is a shift to the power of 2. 0 == no volume, 3 == volume*8
 401  */
 402 void
 403 dsp_change_volume(struct sk_buff *skb, int volume)
 404 {
 405         u8 *volume_change;
 406         int i, ii;
 407         u8 *p;
 408         int shift;
 409
 410         if (volume == 0)
 411                 return;
 412
 413         /* get correct conversion table */
 414         if (volume < 0) {
 415                 shift = volume + 8;
 416                 if (shift < 0)
 417                         shift = 0;
 418         } else {
 419                 shift = volume + 7;
 420                 if (shift > 15)
 421                         shift = 15;
 422         }
 423         volume_change = dsp_audio_volume_change[shift];
 424         i = 0;
 425         ii = skb->len;
 426         p = skb->data;
 427         /* change volume */
 428         while (i < ii) {
 429                 *p = volume_change[*p];
 430                 p++;
 431                 i++;
 432         }
 433 }
 434