/**
* @file compandit.c - implementation test file for integer companding with
* compand/uncompand support & IIR correction
*
* @copy Copyright (C) <2012>
* @author M A Chatterjee
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
*
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
*
* 3. This notice may not be removed or altered from any source
* distribution.
*
*/
#include
#include
#include "companders.h"
//===============================================
//main program for testing the functions
int main (int argc, char *argv[])
{
int ret_val = 0;
int i=0,j=0;
printf("\n============================================================\n");
printf("compandit library quikie program\n");
printf("M. A. Chatterjee (c) 2012\n\n");
printf("These routines were developed for use on embedded projects\n");
printf("for more info see the accompanying compand.txt\n");
printf("\n");
//uncomment to
//show how linear-->alaw-->linear-->alaw progression / quantization error works
/*
{
char alaw=0,alaw2;
short rev=0;
for (i= -32768; i <= 32767; i++)
{
alaw = DIO_LinearToALaw((short)i);
rev = DIO_ALawToLinear(alaw);
alaw2 =DIO_LinearToALaw(rev);
if (alaw != alaw2)
printf("***********");
printf("%7d %7d %7d %7d\n",i,(int)alaw,(int)rev,(int)alaw2);
}
}
// IIR averager examples
//IIR window length of 8 samples, using fractional precision of 4 bits
{
int a3=0, a4=0;
unsigned char rad=4; //4 bits fixed-radix fractional precision
printf(" index wave IIRav(i) IIRav(f) IIRavP2(i) IIRavP2(f)\n");
for (i=0; i < 300; i++)
{
j=(i&0x3f)-20; // triangle wave with range -20 to + 43
a3= DIO_IIRavgFR(a3,8,j,rad);
a4= DIO_IIRavgPower2FR(a4,3,j,rad);
printf("%6d %6d %6d %9.4f %6d %9.4f \n",i,j,
DIO_FR2I(a3,rad),DIO_FR2D(a3,rad) ,DIO_FR2I(a4,rad),DIO_FR2D(a4,rad));
}
}
//IIR window length of 64 samples
{
int a3=0, a4=0;
unsigned char rad=6; //rad is the number of bits of precision
printf(" index wave IIRav(i) IIRav(f) IIRavP2(i) IIRavP2(f)\n");
for (i=0; i < 300; i++)
{
j=(i&0x3f)-20; // triangle wave with range -20 to + 43
a3= DIO_IIRavgFR(a3,64,j,rad);
a4= DIO_IIRavgPower2FR(a4,6,j,rad);
printf("%6d %6d %6d %9.4f %6d %9.4f \n",i,j,
DIO_FR2I(a3,rad),DIO_FR2D(a3,rad) ,DIO_FR2I(a4,rad),DIO_FR2D(a4,rad));
}
}
// */
//Typical microcontroller application. See readme-companders.txt
// the input here simulates an A/D which has a range 0..3.3V mapped as 12 bits (0..4095)
// with a DC bias of 1.55V ==> (1.55/3.3)*4095 counts = 1923 counts
//now window length of 256 is used for rejecting the resistor bias. at 8KHz this window
// would be approx 8000/256 ~= 31 Hz (not quite but explaining Z xforms is beyond what
// can be explained in this small space.)
//we seed the DC average at 3.3/2 = 1.65V (we guess its in the middle) and let the long window
//length hone in on the correct value. (1.65V/3.3V) *4095 = 2048 counts
{
int actualDCbias =1923;
int calculatedDCbias =2048; //2048 is our initial estimate as outlined above
unsigned char windowLenPow2InBits = 8; // 8 bit long window = 256 sample long window
unsigned char rad=6; //rad is the number of bits of precision
calculatedDCbias = DIO_I2FR(calculatedDCbias,rad);
printf(" index wave actDCbias calcDCbias calcDCbias(f) alaw\n");
for (i=0; i < 1000; i++) // if 8000 hz sample rate this represents the number of samples captured
{
j=(((i&0x3f)<<1)-63)+1923; // triangle wave w range 0..127 with a bias set at actualDCbias
calculatedDCbias = DIO_IIRavgPower2FR(calculatedDCbias,windowLenPow2InBits,j,rad);
printf("%6d %6d %6d %6d %9.4f %3d\n",i,j,actualDCbias,
DIO_FR2I(calculatedDCbias,rad),DIO_FR2D(calculatedDCbias,rad),
(int)(DIO_LinearToALaw(j-DIO_FR2I(calculatedDCbias,rad)) ));
}
}
printf("\n");
return ret_val;
}