## Integer to ASCII

January 18, 20132 comments Coded in C
``````/***** integerToAscii.h *****/

#define BASE_OCTAL			8
#define BASE_DECIMAL			10

#define BUFFER_SIZE			32

char* integerToASCII(long int value, int base);

/***** integerToAscii.c *****/

char* integerToASCII(long int value, int base){

int aux;
static char buf[BUFFER_SIZE] = {0};

int isNeg=0;
if (value == 0) {
buf[0]='0';
return &buf[0];
}
if (value<0) {
isNeg = 1;
value *= -1;
}

for(aux=BUFFER_SIZE; value && aux ; --aux, value /= base){
buf[aux] = "0123456789abcdef"[value % base];
}

if (isNeg)  {
buf[aux] = '-';
return &buf[aux];
}

return &buf[aux+1];
}``````

## CRC-16 Calculation

January 16, 20138 comments Coded in C
``````/***** crc16.h *****/
//Tested
#define CRC16_DNP	0x3D65		// DNP, IEC 870, M-BUS, wM-BUS, ...
#define CRC16_CCITT	0x1021		// X.25, V.41, HDLC FCS, Bluetooth, ...

//Other polynoms not tested
#define CRC16_IBM	0x8005		// ModBus, USB, Bisync, CRC-16, CRC-16-ANSI, ...
#define CRC16_T10_DIF	0x8BB7		// SCSI DIF
#define CRC16_DECT	0x0589		// Cordeless Telephones
#define CRC16_ARINC	0xA02B		// ACARS Aplications

#define POLYNOM		CRC16_XXX   // Define the used polynom from one of the aboves

// It calculates the new crc16 with the newByte. Variable crcValue is the actual or initial value (0).
unsigned int crc16(unsigned int crcValue, unsigned char newByte);

/***** crc16.c *****/

#include "crc16.h"

unsigned int crc16(unsigned int crcValue, unsigned char newByte)
{
unsigned char i;

for (i = 0; i < 8; i++) {

if (((crcValue & 0x8000) >> 8) ^ (newByte & 0x80)){
crcValue = (crcValue << 1)  ^ POLYNOM;
}else{
crcValue = (crcValue << 1);
}

newByte <<= 1;
}

return crcValue;
}

/***** EXAMPLE *****/

unsigned int exampleOfUseCRC16 (unsigned char *Data, usigned char len){

unsigned int crc;
unsigned char aux = 0;

crc = 0x0000; //Initialization of crc to 0x0000 for DNP
//crc = 0xFFFF; //Initialization of crc to 0xFFFF for CCITT

while (aux < len){
crc = crc16(crc,Data[aux]);
aux++;
}

return (~crc); //The crc value for DNP it is obtained by NOT operation

//return crc; //The crc value for CCITT
}``````

## Circular FIFO Buffer

January 15, 20137 comments Coded in C
``````/***** circularBuffer.h *****/

#ifndef CIRCULAR_BUFFER_H_
#define CIRCULAR_BUFFER_H_

#define BUFFER_SIZE 128
#define TYPE char

// Check if the buffer it is full
bool isFull();

// Check if the buffer it is empty
bool isEmpty();

// Get the first element from the FIFO queue
TYPE getElement();

// Add an element to the FIFO queue

// Return the number of Elements that are in the FIFO queue
unsigned char getNumberOfElements();

#endif /*CIRCULAR_BUFFER_H_*/

/***** circularBuffer.cpp *****/

#include "circularBuffer.h"

TYPE Buffer[BUFFER_SIZE + 1]; // It needs 1 extra byte to difference full and empty
unsigned char next = 0;
unsigned char first = 0;

bool isFull(){
if (getNumberOfElements() == BUFFER_SIZE){
return true;
}else{
return false;
}
}

bool isEmpty(){
if ( next == first ){
return true;
}else{
return false;
}
}

TYPE getElement(){
TYPE theElement = 0;
if (! isEmpty()){
theElement =  Buffer[first];
if ( first != BUFFER_SIZE ){
first++;
}else{
first = 0;
}
}

return theElement;// Return 0 always if it is empty, must be checked before
}

if (!isFull()){
Buffer[next] = data;
if ( next != BUFFER_SIZE ){
next++;
}else{
next = 0;
}
return true;
}else{
return false;
}
}

unsigned char getNumberOfElements(){
if (next >= first){
return (next - first);
}else{
return (BUFFER_SIZE - next + first);
}
}``````