//-------------------------------------------------------------------
//	mmiodiff.cpp
//
//	This user-space application uses the 'read()' and 'llseek()'
//	functions provided within our '82573.c' device-driver module 
//	to investigate a claim that Intel's Pro1000 gigabit ethernet
//	controller implements the same i/o-memory register-values at
//	two different locations (although this fact is not disclosed
//	in the official Intel programming reference manual); namely,
//	the 128-byte i/o-memory range 0x05400-0x0547F which is named
//	the 'Receive-address Array' in Intel's manual can apparently 
//	be accessed at the alternate i/o-memory range 0x00040-000BF.
//
//		compile using:  $ g++ mmiodiff.cpp -o mmiodiff
//		execute using:  $ ./mmiodiff
//
//	NOTE: This application requires our '82573.c' device-driver.
//
//	------------------------------------------------------------
//	REVISED to examine the following four i/o-memory ranges:
//
//	 0x6000-0x63FF, 0x6400-0x67FF, 0x6800-0x6BFF, 0x6C00-0x6FFF  
//
//	and to count any "mismatches" among corresponding registers.
//	------------------------------------------------------------
//
//	programmer: ALLAN CRUSE
//	written on: 19 FEB 2008
//	revised on: 20 FEB 2008 -- for Question V on Midterm Exam I
//-------------------------------------------------------------------

#include <stdio.h>	// for printf(), perror() 
#include <fcntl.h>	// for open() 
#include <stdlib.h>	// for exit() 
#include <unistd.h>	// for lseek(), read()

#define RANGE_SIZE	0x400		// 1024-byte i/o address-range <---
#define NUM_REGS    (RANGE_SIZE >> 2)	// number of 32-bit registers

char	devname[] = "/dev/82573";	// our device-file's pathname

int main( int argc, char **argv )
{
	// open the device-file for reading
	int	fd = open( devname, O_RDONLY );
	if ( fd < 0 ) { perror( devname ); exit(1); }

	// read register-range 0x06000-0x063FF into a local array
	unsigned int  range1[ NUM_REGS ];
	lseek( fd, 0x06000, SEEK_SET );
	for (int i = 0; i < NUM_REGS; i++) read( fd, &range1[i], 4 );

	// read register-range 0x06400-0x067FF into a local array
	unsigned int  range2[ NUM_REGS ];
	lseek( fd, 0x06400, SEEK_SET );
	for (int i = 0; i < NUM_REGS; i++) read( fd, &range2[i], 4 );

	// read register-range 0x06800-0x06BFF into a local array
	unsigned int  range3[ NUM_REGS ];
	lseek( fd, 0x06800, SEEK_SET );
	for (int i = 0; i < NUM_REGS; i++) read( fd, &range3[i], 4 );

	// read register-range 0x06C00-0x06FFF into a local array
	unsigned int  range4[ NUM_REGS ];
	lseek( fd, 0x06C00, SEEK_SET );
	for (int i = 0; i < NUM_REGS; i++) read( fd, &range4[i], 4 );

	// count the number of occurrences of any 'mismatch' among 
	// any set of four corresponding register-entries (if any)
	int	mismatch = 0;
	for (int i = 0; i < NUM_REGS; i++)
		{
		printf( "\n 0x%04X: ", 4*i );
		printf( " %08X ", range1[ i ] );
		printf( " %08X ", range2[ i ] );
		printf( " %08X ", range3[ i ] );
		printf( " %08X ", range4[ i ] );
		if ( !(	  ( range1[ i ] == range2[ i ] )
			||( range2[ i ] == range3[ i ] )
			||( range3[ i ] == range4[ i ] ) ) ) ++mismatch;
		}
	printf( "\n\n Number of mismatched entries: %d \n\n", mismatch );
}