//	mmstudy1.cpp
//	allan cruse

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/mman.h>

int main( void )
{
	int	mm = open( "/dev/vram", O_RDWR );
	int	vramsize = lseek( mm, 0, SEEK_END );
	printf( "\nvramsize: %d MB \n", vramsize >> 20 );

	int	fd, nbytes;
	char	vmainfo[ 4096 ];
	
	memset( vmainfo, 0, sizeof( vmainfo ) );
	fd = open( "/proc/vma", O_RDONLY );
	nbytes = read( fd, vmainfo, 4095 );
	close( fd );
	if ( nbytes < 0 ) { perror( "read" ); exit(1); }
	printf( "\n%s\n", vmainfo );

	int	prot = ( PROT_READ | PROT_WRITE );
	int	flags = MAP_SHARED;
	long	*vram = (long*)mmap( 0, vramsize, prot, flags, mm, 0 );
	printf( "\nvram=%08X \n", vram );
	
	memset( vmainfo, 0, sizeof( vmainfo ) );
	fd = open( "/proc/vma", O_RDONLY );
	nbytes = read( fd, vmainfo, 4095 );
	close( fd );
	if ( nbytes < 0 ) { perror( "read" ); exit(1); }
	printf( "\n%s\n", vmainfo );

	munmap( vram, vramsize );

	memset( vmainfo, 0, sizeof( vmainfo ) );
	fd = open( "/proc/vma", O_RDONLY );
	nbytes = read( fd, vmainfo, 4095 );
	close( fd );
	if ( nbytes < 0 ) { perror( "read" ); exit(1); }
	printf( "\n%s\n", vmainfo );
}