Thread: Read one and multiple bytes in function

Hello

I need help in my embedded project. assume array is loaded with five bytes so we know the location of each byte and data stored in the location.

byte 1 = location for byte1 6422296 = 00
byte 2 = location for byte2 6422300 = 01

byte 3 = location for byte3 6422304 = 02
byte 4 = location for byte4 6422308 = 03
byte 5 = location for byte5 6422312 = 04


I need to design two function

*read one byte
*read five bytes

In the read one byte function, function would take the memory location of one byte and save result

in read multiple byte function, read five bytes by calling read one byte function

I made my attempt

Code:

#include<stdio.h> 
// Function to read one byte 
void ReadByte (int *N)
{
     //loop to read 8 bits 
    for ( n = 0; n <8; n++ )     
    {
       /*read each bit of one byte */
    }
}
 
// Function to read five byte  
void ReadMultipleByte (int *P )
{
    //loop to read 5 bytes
    for ( n = 0; n <5; n++ )
    {
	   // call the function to read one byte and it will run five time in loop
        
    }
}
void main ()
{
	int n;
    int Data[]= {0,1,2,3,4}; //five bytes are stored into array 
	
	ReadMultipleByte (&Data)
    return 0;
}

Originally Posted by Salem

Well you should change your data type from 'int' to 'unsigned char' to begin with.

I have done

Code:

#include<stdio.h> 
// Function to read one byte 
void ReadByte (unsigned char *N)
{
     //loop to read 8 bits 
    for ( n = 0; n <8; n++ )     
    {
       /*read each bit of one byte */
    }
}
 
// Function to read five byte  
void ReadMultipleByte (unsigned char *P )
{
    //loop to read 5 bytes
    for ( n = 0; n <5; n++ )
    {
	   // call the function to read one byte and it will run five time in loop
        
    }
}
void main ()
{
	int n;
    unsigned char Data[]= {0,1,2,3,4}; //five bytes are stored into array 
	
	ReadMultipleByte (&Data[0])
    return 0;
}

Is my logic correct ?

Originally Posted by Salem

Looks better.

Now just complete the code for the comments.

My attempt

Code:

#include<stdio.h> 

// Function to read one byte 
void ReadByte (unsigned char *byteAddress)
{
     //loop to read 8 bits 
    for ( n = 0; n <8; n++ )     
    {
		 if ( condition1 ) 
             *byteAddress |= 1 ; 
		 
         if ( n < 7 ) 
             *byteAddress <<= 1 ;   
    }
	
}
  
// Function to read five byte  
void ReadMultipleByte ( unsigned char *byteAddress)
{
	int n;
	unsigned char R;
    //loop to read 5 bytes
    for ( n = 0; n <5; n++ )   
    {
      R =  ReadByte( unsigned char *byteAddress)    // call the function to read one byte and it will run five time in loop
	  ++byteAddress;
    
    }
}
void main ()
{
    int n;
    unsigned char Data[]= {0,1,2,3,4}; //five bytes are stored into array 
     
    ReadMultipleByte ( Data])
    return 0;
}

following approach work for me

Code:

#include<stdio.h>    

int read (unsigned int N, unsigned int *p);
  
int read (unsigned int N, unsigned int *p)
{
    int i;
	   for (int i = N-1; i >= 0; i--) {   
	   printf("\n read address %p \n ", (p + N-1));   
       printf("value store at this address is = %d \n", *( p + N-1));
       --p; 	   
    }    
}
 
     
int main()    
{    
    int s;  int N = 5 ;  // length of array     
    
    //Initialize array     
    int Data[] = {1, 2, 3, 4, 5};     
         
    printf("Original array: \n");    
    for (int i = 0; i < N; i++) {  
        printf("%p  = %d \n", &Data[i], Data[i] ); 	 
    }      
        
    printf("\n");    
        
    printf("Array in reverse order: \n");    
    //Loop through the array in reverse order    
    for (int i = N-1; i >= 0; i--) {   
        printf("%p  = %d \n", &Data[i], Data[i] ); 	 
    }
     s= read (N, Data);	
    return 0;    
}

Original array:
0061FF0C = 1
0061FF10 = 2
0061FF14 = 3
0061FF18 = 4
0061FF1C = 5


Array in reverse order:
0061FF1C = 5
0061FF18 = 4
0061FF14 = 3
0061FF10 = 2
0061FF0C = 1


read address 0061FF1C
value store at this address is = 5


read address 0061FF18
value store at this address is = 4


read address 0061FF14
value store at this address is = 3


read address 0061FF10
value store at this address is = 2


read address 0061FF0C
value store at this address is = 1