1 files changed, 104 insertions, 0 deletions

diff --git a/src/fs/char_dev.c b/src/fs/char_dev.c
new file mode 100644
index 0000000..6932e1e
--- /dev/null
+++ b/src/fs/char_dev.c
@@ -0,0 +1,104 @@
+/*
+ *  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);
+}