434 lines
11 KiB
C
434 lines
11 KiB
C
/*
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* Audio support data for mISDN_dsp.
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*
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* Copyright 2002/2003 by Andreas Eversberg (jolly@eversberg.eu)
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* Rewritten by Peter
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*
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* This software may be used and distributed according to the terms
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* of the GNU General Public License, incorporated herein by reference.
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*
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*/
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#include <linux/delay.h>
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#include <linux/mISDNif.h>
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#include <linux/mISDNdsp.h>
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#include "core.h"
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#include "dsp.h"
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/* ulaw[unsigned char] -> signed 16-bit */
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s32 dsp_audio_ulaw_to_s32[256];
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/* alaw[unsigned char] -> signed 16-bit */
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s32 dsp_audio_alaw_to_s32[256];
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s32 *dsp_audio_law_to_s32;
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EXPORT_SYMBOL(dsp_audio_law_to_s32);
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/* signed 16-bit -> law */
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u8 dsp_audio_s16_to_law[65536];
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EXPORT_SYMBOL(dsp_audio_s16_to_law);
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/* alaw -> ulaw */
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u8 dsp_audio_alaw_to_ulaw[256];
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/* ulaw -> alaw */
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static u8 dsp_audio_ulaw_to_alaw[256];
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u8 dsp_silence;
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/*****************************************************
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* generate table for conversion of s16 to alaw/ulaw *
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*****************************************************/
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#define AMI_MASK 0x55
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static inline unsigned char linear2alaw(short int linear)
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{
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int mask;
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int seg;
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int pcm_val;
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static int seg_end[8] = {
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0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF
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};
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pcm_val = linear;
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if (pcm_val >= 0) {
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/* Sign (7th) bit = 1 */
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mask = AMI_MASK | 0x80;
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} else {
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/* Sign bit = 0 */
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mask = AMI_MASK;
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pcm_val = -pcm_val;
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}
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/* Convert the scaled magnitude to segment number. */
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for (seg = 0; seg < 8; seg++) {
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if (pcm_val <= seg_end[seg])
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break;
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}
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/* Combine the sign, segment, and quantization bits. */
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return ((seg << 4) |
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((pcm_val >> ((seg) ? (seg + 3) : 4)) & 0x0F)) ^ mask;
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}
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static inline short int alaw2linear(unsigned char alaw)
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{
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int i;
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int seg;
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alaw ^= AMI_MASK;
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i = ((alaw & 0x0F) << 4) + 8 /* rounding error */;
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seg = (((int) alaw & 0x70) >> 4);
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if (seg)
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i = (i + 0x100) << (seg - 1);
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return (short int) ((alaw & 0x80) ? i : -i);
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}
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static inline short int ulaw2linear(unsigned char ulaw)
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{
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short mu, e, f, y;
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static short etab[] = {0, 132, 396, 924, 1980, 4092, 8316, 16764};
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mu = 255 - ulaw;
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e = (mu & 0x70) / 16;
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f = mu & 0x0f;
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y = f * (1 << (e + 3));
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y += etab[e];
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if (mu & 0x80)
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y = -y;
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return y;
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}
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#define BIAS 0x84 /*!< define the add-in bias for 16 bit samples */
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static unsigned char linear2ulaw(short sample)
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{
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static int exp_lut[256] = {
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0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
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4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
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5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
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5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
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6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
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6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
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6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
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6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7};
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int sign, exponent, mantissa;
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unsigned char ulawbyte;
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/* Get the sample into sign-magnitude. */
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sign = (sample >> 8) & 0x80; /* set aside the sign */
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if (sign != 0)
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sample = -sample; /* get magnitude */
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/* Convert from 16 bit linear to ulaw. */
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sample = sample + BIAS;
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exponent = exp_lut[(sample >> 7) & 0xFF];
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mantissa = (sample >> (exponent + 3)) & 0x0F;
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ulawbyte = ~(sign | (exponent << 4) | mantissa);
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return ulawbyte;
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}
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static int reverse_bits(int i)
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{
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int z, j;
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z = 0;
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for (j = 0; j < 8; j++) {
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if ((i & (1 << j)) != 0)
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z |= 1 << (7 - j);
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}
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return z;
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}
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void dsp_audio_generate_law_tables(void)
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{
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int i;
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for (i = 0; i < 256; i++)
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dsp_audio_alaw_to_s32[i] = alaw2linear(reverse_bits(i));
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for (i = 0; i < 256; i++)
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dsp_audio_ulaw_to_s32[i] = ulaw2linear(reverse_bits(i));
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for (i = 0; i < 256; i++) {
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dsp_audio_alaw_to_ulaw[i] =
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linear2ulaw(dsp_audio_alaw_to_s32[i]);
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dsp_audio_ulaw_to_alaw[i] =
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linear2alaw(dsp_audio_ulaw_to_s32[i]);
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}
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}
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void
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dsp_audio_generate_s2law_table(void)
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{
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int i;
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if (dsp_options & DSP_OPT_ULAW) {
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/* generating ulaw-table */
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for (i = -32768; i < 32768; i++) {
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dsp_audio_s16_to_law[i & 0xffff] =
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reverse_bits(linear2ulaw(i));
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}
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} else {
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/* generating alaw-table */
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for (i = -32768; i < 32768; i++) {
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dsp_audio_s16_to_law[i & 0xffff] =
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reverse_bits(linear2alaw(i));
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}
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}
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}
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/*
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* the seven bit sample is the number of every second alaw-sample ordered by
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* aplitude. 0x00 is negative, 0x7f is positive amplitude.
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*/
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u8 dsp_audio_seven2law[128];
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u8 dsp_audio_law2seven[256];
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/********************************************************************
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* generate table for conversion law from/to 7-bit alaw-like sample *
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********************************************************************/
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void
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dsp_audio_generate_seven(void)
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{
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int i, j, k;
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u8 spl;
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u8 sorted_alaw[256];
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/* generate alaw table, sorted by the linear value */
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for (i = 0; i < 256; i++) {
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j = 0;
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for (k = 0; k < 256; k++) {
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if (dsp_audio_alaw_to_s32[k]
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< dsp_audio_alaw_to_s32[i])
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j++;
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}
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sorted_alaw[j] = i;
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}
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/* generate tabels */
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for (i = 0; i < 256; i++) {
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/* spl is the source: the law-sample (converted to alaw) */
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spl = i;
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if (dsp_options & DSP_OPT_ULAW)
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spl = dsp_audio_ulaw_to_alaw[i];
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/* find the 7-bit-sample */
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for (j = 0; j < 256; j++) {
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if (sorted_alaw[j] == spl)
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break;
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}
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/* write 7-bit audio value */
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dsp_audio_law2seven[i] = j >> 1;
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}
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for (i = 0; i < 128; i++) {
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spl = sorted_alaw[i << 1];
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if (dsp_options & DSP_OPT_ULAW)
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spl = dsp_audio_alaw_to_ulaw[spl];
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dsp_audio_seven2law[i] = spl;
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}
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}
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/* mix 2*law -> law */
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u8 dsp_audio_mix_law[65536];
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/******************************************************
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* generate mix table to mix two law samples into one *
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******************************************************/
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void
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dsp_audio_generate_mix_table(void)
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{
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int i, j;
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s32 sample;
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i = 0;
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while (i < 256) {
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j = 0;
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while (j < 256) {
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sample = dsp_audio_law_to_s32[i];
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sample += dsp_audio_law_to_s32[j];
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if (sample > 32767)
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sample = 32767;
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if (sample < -32768)
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sample = -32768;
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dsp_audio_mix_law[(i<<8)|j] =
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dsp_audio_s16_to_law[sample & 0xffff];
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j++;
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}
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i++;
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}
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}
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/*************************************
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* generate different volume changes *
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*************************************/
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static u8 dsp_audio_reduce8[256];
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static u8 dsp_audio_reduce7[256];
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static u8 dsp_audio_reduce6[256];
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static u8 dsp_audio_reduce5[256];
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static u8 dsp_audio_reduce4[256];
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static u8 dsp_audio_reduce3[256];
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static u8 dsp_audio_reduce2[256];
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static u8 dsp_audio_reduce1[256];
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static u8 dsp_audio_increase1[256];
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static u8 dsp_audio_increase2[256];
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static u8 dsp_audio_increase3[256];
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static u8 dsp_audio_increase4[256];
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static u8 dsp_audio_increase5[256];
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static u8 dsp_audio_increase6[256];
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static u8 dsp_audio_increase7[256];
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static u8 dsp_audio_increase8[256];
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static u8 *dsp_audio_volume_change[16] = {
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dsp_audio_reduce8,
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dsp_audio_reduce7,
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dsp_audio_reduce6,
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dsp_audio_reduce5,
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dsp_audio_reduce4,
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dsp_audio_reduce3,
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dsp_audio_reduce2,
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dsp_audio_reduce1,
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dsp_audio_increase1,
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dsp_audio_increase2,
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dsp_audio_increase3,
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dsp_audio_increase4,
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dsp_audio_increase5,
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dsp_audio_increase6,
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dsp_audio_increase7,
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dsp_audio_increase8,
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};
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void
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dsp_audio_generate_volume_changes(void)
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{
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register s32 sample;
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int i;
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int num[] = { 110, 125, 150, 175, 200, 300, 400, 500 };
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int denum[] = { 100, 100, 100, 100, 100, 100, 100, 100 };
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i = 0;
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while (i < 256) {
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dsp_audio_reduce8[i] = dsp_audio_s16_to_law[
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(dsp_audio_law_to_s32[i] * denum[7] / num[7]) & 0xffff];
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dsp_audio_reduce7[i] = dsp_audio_s16_to_law[
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(dsp_audio_law_to_s32[i] * denum[6] / num[6]) & 0xffff];
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dsp_audio_reduce6[i] = dsp_audio_s16_to_law[
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(dsp_audio_law_to_s32[i] * denum[5] / num[5]) & 0xffff];
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dsp_audio_reduce5[i] = dsp_audio_s16_to_law[
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(dsp_audio_law_to_s32[i] * denum[4] / num[4]) & 0xffff];
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dsp_audio_reduce4[i] = dsp_audio_s16_to_law[
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(dsp_audio_law_to_s32[i] * denum[3] / num[3]) & 0xffff];
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dsp_audio_reduce3[i] = dsp_audio_s16_to_law[
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(dsp_audio_law_to_s32[i] * denum[2] / num[2]) & 0xffff];
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dsp_audio_reduce2[i] = dsp_audio_s16_to_law[
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(dsp_audio_law_to_s32[i] * denum[1] / num[1]) & 0xffff];
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dsp_audio_reduce1[i] = dsp_audio_s16_to_law[
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(dsp_audio_law_to_s32[i] * denum[0] / num[0]) & 0xffff];
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sample = dsp_audio_law_to_s32[i] * num[0] / denum[0];
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if (sample < -32768)
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sample = -32768;
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else if (sample > 32767)
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sample = 32767;
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dsp_audio_increase1[i] = dsp_audio_s16_to_law[sample & 0xffff];
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sample = dsp_audio_law_to_s32[i] * num[1] / denum[1];
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if (sample < -32768)
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sample = -32768;
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else if (sample > 32767)
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sample = 32767;
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dsp_audio_increase2[i] = dsp_audio_s16_to_law[sample & 0xffff];
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sample = dsp_audio_law_to_s32[i] * num[2] / denum[2];
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if (sample < -32768)
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sample = -32768;
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else if (sample > 32767)
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sample = 32767;
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dsp_audio_increase3[i] = dsp_audio_s16_to_law[sample & 0xffff];
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sample = dsp_audio_law_to_s32[i] * num[3] / denum[3];
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if (sample < -32768)
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sample = -32768;
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else if (sample > 32767)
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sample = 32767;
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dsp_audio_increase4[i] = dsp_audio_s16_to_law[sample & 0xffff];
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sample = dsp_audio_law_to_s32[i] * num[4] / denum[4];
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if (sample < -32768)
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sample = -32768;
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else if (sample > 32767)
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sample = 32767;
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dsp_audio_increase5[i] = dsp_audio_s16_to_law[sample & 0xffff];
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sample = dsp_audio_law_to_s32[i] * num[5] / denum[5];
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if (sample < -32768)
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sample = -32768;
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else if (sample > 32767)
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sample = 32767;
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dsp_audio_increase6[i] = dsp_audio_s16_to_law[sample & 0xffff];
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sample = dsp_audio_law_to_s32[i] * num[6] / denum[6];
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if (sample < -32768)
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sample = -32768;
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else if (sample > 32767)
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sample = 32767;
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dsp_audio_increase7[i] = dsp_audio_s16_to_law[sample & 0xffff];
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sample = dsp_audio_law_to_s32[i] * num[7] / denum[7];
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if (sample < -32768)
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sample = -32768;
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else if (sample > 32767)
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sample = 32767;
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dsp_audio_increase8[i] = dsp_audio_s16_to_law[sample & 0xffff];
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i++;
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}
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}
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/**************************************
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* change the volume of the given skb *
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**************************************/
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/* this is a helper function for changing volume of skb. the range may be
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* -8 to 8, which is a shift to the power of 2. 0 == no volume, 3 == volume*8
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*/
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void
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dsp_change_volume(struct sk_buff *skb, int volume)
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{
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u8 *volume_change;
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int i, ii;
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u8 *p;
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int shift;
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if (volume == 0)
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return;
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/* get correct conversion table */
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if (volume < 0) {
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shift = volume + 8;
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if (shift < 0)
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shift = 0;
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} else {
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shift = volume + 7;
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if (shift > 15)
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shift = 15;
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}
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volume_change = dsp_audio_volume_change[shift];
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i = 0;
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ii = skb->len;
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p = skb->data;
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/* change volume */
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while (i < ii) {
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*p = volume_change[*p];
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p++;
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i++;
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}
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}
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