DE1SoCfpga.cpp

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <iostream>
#include "DE1SoCfpga.h"
using namespace std;

//Class for mapping virtual memory to physical memory, and then reading from and writing to that memory

// Physical base address of FPGA Devices
const unsigned int LW_BRIDGE_BASE 	= 0xC0000000;  // Base offset, adjusted to include room for back buffer offset

// Length of memory-mapped IO window
const unsigned int LW_BRIDGE_SPAN 	= 0x3FFEC700;  // Address map size


   //Constructor for class, initializes the board, and stores the virtual mapping in pBase
	DE1SoCfpga::DE1SoCfpga()
	{
	         // Open /dev/mem to give access to physical addresses
       		 fd = open( "/dev/mem", (O_RDWR | O_SYNC));
       		 if (fd == -1)                  //  check for errors in openning /dev/mem
       		 {
       		 	cout << "ERROR: could not open /dev/mem..." << endl;
       			 exit(1);
       		 }

 		  // Get a mapping from physical addresses to virtual addresses
  		 char *virtual_base = (char *)mmap (NULL, LW_BRIDGE_SPAN, (PROT_READ | PROT_WRITE), MAP_SHARED, fd, LW_BRIDGE_BASE);
  		 if (virtual_base == MAP_FAILED)              // check for errors
  		 {
      			cout << "ERROR: mmap() failed..." << endl;
     			 close (fd);              // close memory before exiting
     			 exit(1);        // Returns 1 to the operating system;
  		 }
   		pBase = virtual_base;   //store the mapping in pBase
	}
   //Deconstructor, frees up the memory allocated in the constructor
	DE1SoCfpga::~DE1SoCfpga()
	{
	        if (munmap (pBase, LW_BRIDGE_SPAN) != 0)
       		 {
      			cout << "ERROR: munmap() failed..." << endl;
     			 exit(1);
        	 }
   		close (fd);  // close memory
	}
/**
 * Write a 4-byte value at the specified general-purpose I/O location.
 * @parem offset	Offset where device is mapped.
 * @param value	Value to be written.
 */
	void DE1SoCfpga::RegisterWrite (unsigned int reg_offset, int value)
	{
		* (volatile unsigned int *)(pBase + reg_offset) = value;
	}
/**
 * Read a 4-byte value from the specified general-purpose I/O location.
 * @param offset	Offset where device is mapped.
 * @return		Value read.
 */
	int DE1SoCfpga::RegisterRead(unsigned int reg_offset)
	{
		return * (volatile unsigned int *)(pBase + reg_offset);
	}