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/*
* linux/fs/char_dev.c
*
* (C) 1991 Linus Torvalds
*/
#include <errno.h>
#include <sys/types.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <asm/segment.h>
#include <asm/io.h>
extern int tty_read(unsigned minor,char * buf,int count);
extern int tty_write(unsigned minor,char * buf,int count);
typedef int (*crw_ptr)(int rw,unsigned minor,char * buf,int count,off_t * pos);
static int rw_ttyx(int rw,unsigned minor,char * buf,int count,off_t * pos)
{
return ((rw==READ)?tty_read(minor,buf,count):
tty_write(minor,buf,count));
}
static int rw_tty(int rw,unsigned minor,char * buf,int count, off_t * pos)
{
if (current->tty<0)
return -EPERM;
return rw_ttyx(rw,current->tty,buf,count,pos);
}
static int rw_ram(int rw,char * buf, int count, off_t *pos)
{
return -EIO;
}
static int rw_mem(int rw,char * buf, int count, off_t * pos)
{
return -EIO;
}
static int rw_kmem(int rw,char * buf, int count, off_t * pos)
{
return -EIO;
}
static int rw_port(int rw,char * buf, int count, off_t * pos)
{
int i=*pos;
while (count-->0 && i<65536) {
if (rw==READ)
put_fs_byte(inb(i),buf++);
else
outb(get_fs_byte(buf++),i);
i++;
}
i -= *pos;
*pos += i;
return i;
}
static int rw_memory(int rw, unsigned minor, char * buf, int count, off_t * pos)
{
switch(minor) {
case 0:
return rw_ram(rw,buf,count,pos);
case 1:
return rw_mem(rw,buf,count,pos);
case 2:
return rw_kmem(rw,buf,count,pos);
case 3:
return (rw==READ)?0:count; /* rw_null */
case 4:
return rw_port(rw,buf,count,pos);
default:
return -EIO;
}
}
#define NRDEVS ((sizeof (crw_table))/(sizeof (crw_ptr)))
static crw_ptr crw_table[]={
NULL, /* nodev */
rw_memory, /* /dev/mem etc */
NULL, /* /dev/fd */
NULL, /* /dev/hd */
rw_ttyx, /* /dev/ttyx */
rw_tty, /* /dev/tty */
NULL, /* /dev/lp */
NULL}; /* unnamed pipes */
int rw_char(int rw,int dev, char * buf, int count, off_t * pos)
{
crw_ptr call_addr;
if (MAJOR(dev)>=NRDEVS)
return -ENODEV;
if (!(call_addr=crw_table[MAJOR(dev)]))
return -ENODEV;
return call_addr(rw,MINOR(dev),buf,count,pos);
}
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