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/*****************************************************************************/
/*
* genpamtbl.c -- Channel simulator for the PAM channel.
*
* Copyright (C) 1999-2000 Thomas Sailer (sailer@ife.ee.ethz.ch)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Please note that the GPL allows you to use the driver, NOT the radio.
* In order to use the radio, you need a license from the communications
* authority of your country.
*
*/
/*****************************************************************************/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "pam.h"
#include "mat.h"
#include <math.h>
#include <stdio.h>
/* ---------------------------------------------------------------------- */
/*
* Maximum length shift register connections
* (cf. Proakis, Digital Communications, p. 399
*
* 2 1,2
* 3 1,3
* 4 1,4
* 5 1,4
* 6 1,6
* 7 1,7
* 8 1,5,6,7
* 9 1,6
* 10 1,8
* 11 1,10
* 12 1,7,9,12
* 13 1,10,11,13
* 14 1,5,9,14
* 15 1,15
* 16 1,5,14,16
* 17 1,15
* 18 1,12
*/
#define TAP_2 ((1<<1)|(1<<0))
#define TAP_3 ((1<<2)|(1<<0))
#define TAP_4 ((1<<3)|(1<<0))
#define TAP_5 ((1<<4)|(1<<1))
#define TAP_6 ((1<<5)|(1<<0))
#define TAP_7 ((1<<6)|(1<<0))
#define TAP_8 ((1<<7)|(1<<3)|(1<<2)|(1<<1))
#define TAP_9 ((1<<8)|(1<<3))
#define TAP_10 ((1<<9)|(1<<2))
#define TAP_11 ((1<<10)|(1<<1))
#define TAP_12 ((1<<11)|(1<<5)|(1<<3)|(1<<0))
#define TAP_13 ((1<<12)|(1<<3)|(1<<2)|(1<<0))
#define TAP_14 ((1<<13)|(1<<9)|(1<<5)|(1<<0))
#define TAP_15 ((1<<14)|(1<<0))
#define TAP_16 ((1<<15)|(1<<11)|(1<<2)|(1<<0))
#define TAP_17 ((1<<16)|(1<<2))
#define TAP_18 ((1<<17)|(1<<6))
#define MASK_2 ((1<<2)-1)
#define MASK_3 ((1<<3)-1)
#define MASK_4 ((1<<4)-1)
#define MASK_5 ((1<<5)-1)
#define MASK_6 ((1<<6)-1)
#define MASK_7 ((1<<7)-1)
#define MASK_8 ((1<<8)-1)
#define MASK_9 ((1<<9)-1)
#define MASK_10 ((1<<10)-1)
#define MASK_11 ((1<<11)-1)
#define MASK_12 ((1<<12)-1)
#define MASK_13 ((1<<13)-1)
#define MASK_14 ((1<<14)-1)
#define MASK_15 ((1<<15)-1)
#define MASK_16 ((1<<16)-1)
#define MASK_17 ((1<<17)-1)
#define MASK_18 ((1<<18)-1)
#define TAPS TAP_5
#define MASK MASK_5
/* ---------------------------------------------------------------------- */
extern __inline__ unsigned int hweight32(unsigned int w)
{
unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555);
res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F);
res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF);
return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF);
}
/* ---------------------------------------------------------------------- */
static int frmatprintf(FILE *f, const char *name, unsigned int size1, unsigned int stride1,
unsigned int size2, unsigned int stride2, const float *m)
{
unsigned int i, j;
int ret = 0;
fprintf(f, "%s = [", name);
for (i = 0; i < size1; i++) {
for (j = 0; j < size2; j++)
ret += fprintf(f, " %g", m[i*stride1 + j*stride2]);
if (i+1 < size1)
ret += fprintf(f, " ;\n ");
}
ret += fprintf(f, " ];\n");
return ret;
}
static void gentrain(FILE *f)
{
unsigned int pn = 0xaaaaaaaa;
int trsym[2*TRAINBITS];
int sum;
unsigned int i, j, new;
float ma[OBSTRAINBITS*CHANNELLEN], mat[CHANNELLEN*OBSTRAINBITS], mata[CHANNELLEN*CHANNELLEN];
float matainv[CHANNELLEN*CHANNELLEN], matainvat[CHANNELLEN*OBSTRAINBITS];
fprintf(f, "/*\n trsym = [");
for (sum = i = 0; i < TRAINBITS; i++) {
new = hweight32(pn & TAPS) & 1;
pn = ((pn << 1) | new) & MASK;
if (i == TRAINBITS-1)
new = sum < 0;
trsym[i+TRAINBITS] = trsym[i] = -((-new) | 1);
sum += trsym[i];
fprintf(f, " %d", trsym[i]);
}
fprintf(f, " ];\n trsymcc = [");
for (i = 0; i < TRAINBITS; i++) {
for (sum = 0, j = 0; j < TRAINBITS; j++)
sum += trsym[j] * trsym[i+j];
fprintf(f, " %d", sum);
}
fprintf(f, " ];\n");
for (i = 0; i < OBSTRAINBITS; i++)
for (j = 0; j < CHANNELLEN; j++)
ma[i*CHANNELLEN+j] = trsym[i+j];
frmatprintf(f, "a", OBSTRAINBITS, CHANNELLEN, CHANNELLEN, 1, ma);
/* transpose it */
frtranspose(mat, ma, OBSTRAINBITS, CHANNELLEN);
frmul(mata, mat, ma, CHANNELLEN, OBSTRAINBITS, CHANNELLEN);
frinv(matainv, mata, CHANNELLEN);
frmul(matainvat, matainv, mat, CHANNELLEN, CHANNELLEN, OBSTRAINBITS);
frmatprintf(f, "atainvat", CHANNELLEN, OBSTRAINBITS, OBSTRAINBITS, 1, matainvat);
fprintf(f, " */\n\n");
/* generate C code */
fprintf(f, "static const unsigned char trainsymbmap[%u] = {\n\t", (TRAINBITS+7) / 8);
for (i = 0;;) {
for (new = j = 0; j < 8; j++)
if (trsym[i+j] > 0)
new |= 1 << j;
fprintf(f, "0x%02x", new);
i += 8;
if (i >= TRAINBITS)
break;
fprintf(f, ", ");
}
fprintf(f, "\n};\n\nstatic const int trainsyms[%u] = {\n\t", TRAINBITS);
for (i = 0;;) {
fprintf(f, "%d", trsym[i]);
if ((++i) >= TRAINBITS)
break;
if (!(i & 15)) {
fprintf(f, ",\n\t");
continue;
}
fprintf(f, ", ");
}
fprintf(f, "\n};\n\nstatic const int trainmat[%u] = {\n", CHANNELLEN*OBSTRAINBITS);
for (i = 0; i < CHANNELLEN; i++) {
fprintf(f, "\t");
for (j = 0; j < OBSTRAINBITS; j++) {
fprintf(f, "%d", (int)((1 << 16) * matainvat[i*OBSTRAINBITS+j]));
if (i == CHANNELLEN-1 && j == OBSTRAINBITS-1)
continue;
if ((j & 7) == 7 && j != OBSTRAINBITS-1) {
fprintf(f, ",\n\t");
continue;
}
fprintf(f, ", ");
}
fprintf(f, "\n");
}
fprintf(f, "};\n\n");
/* calculate MLSE root and toor node */
for (i = j = 0; i < CHANNELLEN-1; i++)
if (trsym[TRAINBITS-1-i] > 0)
j |= 1 << i;
fprintf(f, "#define MLSEROOTNODE 0x%x\n", j);
for (i = j = 0; i < CHANNELLEN-1; i++)
if (trsym[CHANNELLEN-2-i] > 0)
j |= 1 << i;
fprintf(f, "#define MLSETOORNODE 0x%x\n\n", j);
}
#define TXRCOSALPHA 0.4
#define RXRCOSALPHA 0.4
#define TXFILTERRELAX 1.4
#define RXFILTERRELAX 1.4
static inline double sinc(double x)
{
double arg = x * M_PI;
if (fabs(arg) < 1e-10)
return 1;
return sin(arg) / arg;
}
static inline double hamming(double x)
{
return 0.54-0.46*cos((2*M_PI)*x);
}
static void gentxfilt(FILE *f)
{
float coeff[TXFILTLEN * TXFILTOVER];
double tmul, at, t, f1, f2;
int i, j;
tmul = 1.0 / TXFILTOVER;
#if 0
tmul *= TXFILTERRELAX;
for (i = 0; i < TXFILTLEN * TXFILTOVER; i++)
coeff[i] = sinc((i - 0.5 * TXFILTLEN * TXFILTOVER)*tmul)
* hamming(i * (1.0 / (TXFILTLEN * TXFILTOVER - 1)));
#else
for (i = 0; i < TXFILTLEN * TXFILTOVER; i++) {
t = (i - 0.5 * TXFILTLEN * TXFILTOVER) * tmul;
at = t * TXRCOSALPHA;
f1 = 1 - 4 * at * at;
if (fabs(f1) < 1e-10)
f2 = M_PI * (1.0 / 8.0) * sin(M_PI * at) / at;
else
f2 = cos(M_PI * at) / f1;
coeff[i] = sinc(t) * f2;
}
#endif
for (f1 = 0, i = 0; i < TXFILTOVER; i++) {
for (f2 = 0, j = 0; j < TXFILTLEN; j++)
f2 += fabs(coeff[j*TXFILTOVER+i]);
if (f2 > f1)
f1 = f2;
}
f2 = 32767 / f1;
fprintf(f, "/*\n txfilt = [");
for (i = 0;;) {
fprintf(f, " %g ;", coeff[i]);
if ((++i) >= TXFILTLEN * TXFILTOVER)
break;
if (i & 3)
continue;
fprintf(f, "\n ");
}
fprintf(f, " ];\n abssum = %g;\n semilogy((0:%u)/%u,abs(fft(txfilt)))\n */\n\nstatic const int txfilter[%u][%u] = {",
f1, TXFILTLEN * TXFILTOVER - 1, TXFILTLEN * TXFILTOVER, TXFILTOVER, TXFILTLEN);
for (i = 0;;) {
fprintf(f, "\n\t{");
for (j = 0;;) {
fprintf(f, " %d", (int)(f2 * coeff[j*TXFILTOVER+i]));
if ((++j) >= TXFILTLEN)
break;
fprintf(f, ",");
}
fprintf(f, " }");
if ((++i) >= TXFILTOVER)
break;
fprintf(f, ",");
}
fprintf(f, "\n};\n\n");
}
static void genrxfilt(FILE *f)
{
float coeff[RXFILTLEN * RXFILTOVER];
double tmul, at, t, f1, f2;
int i, j;
tmul = 1.0 * BITRATE / RXFILTOVER / SAMPLERATE;
#if 1
tmul *= RXFILTERRELAX;
for (i = 0; i < RXFILTLEN * RXFILTOVER; i++)
coeff[i] = sinc((i - 0.5 * RXFILTLEN * RXFILTOVER)*tmul)
* hamming(i * (1.0 / (RXFILTLEN * RXFILTOVER - 1)));
#else
for (i = 0; i < RXFILTLEN * RXFILTOVER; i++) {
t = (i - 0.5 * RXFILTLEN * RXFILTOVER) * tmul;
at = t * RXRCOSALPHA;
f1 = 1 - 4 * at * at;
if (fabs(f1) < 1e-10)
f2 = M_PI * (1.0 / 8.0) * sin(M_PI * at) / at;
else
f2 = cos(M_PI * at) / f1;
coeff[i] = sinc(t) * f2;
}
#endif
for (f1 = 0, i = 0; i < RXFILTOVER; i++) {
for (f2 = 0, j = 0; j < RXFILTLEN; j++)
f2 += fabs(coeff[j*RXFILTOVER+i]);
if (f2 > f1)
f1 = f2;
}
f2 = 65535 / f1;
fprintf(f, "/*\n rxfilt = [");
for (i = 0;;) {
fprintf(f, " %g ;", coeff[i]);
if ((++i) >= RXFILTLEN * RXFILTOVER)
break;
if (i & 3)
continue;
fprintf(f, "\n ");
}
fprintf(f, " ];\n abssum = %g;\n semilogy((0:%u)/%u,abs(fft(rxfilt)))\n */\n\nstatic const int rxfilter[%u][%u] = {",
f1, RXFILTLEN * RXFILTOVER - 1, RXFILTLEN * RXFILTOVER, RXFILTOVER, RXFILTLEN);
for (i = 0;;) {
fprintf(f, "\n\t{");
for (j = 0;;) {
fprintf(f, " %d", (int)(f2 * coeff[j*RXFILTOVER+i]));
if ((++j) >= RXFILTLEN)
break;
fprintf(f, ",");
}
fprintf(f, " }");
if ((++i) >= RXFILTOVER)
break;
fprintf(f, ",");
}
fprintf(f, "\n};\n\n");
}
/* ---------------------------------------------------------------------- */
int main(int argc, char *argv[])
{
gentrain(stdout);
gentxfilt(stdout);
genrxfilt(stdout);
return 0;
}
|
