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#include <bios.h>
#include <fcntl.h>
#include <errno.h>
#include "io.h"
#include "rawio.h"
static int op_open();
static int op_close();
static int op_read();
static int op_write();
static long op_lseek();
static int fileops();
int
open(name, flags, mode)
char * name;
int flags, mode;
{
__files = fileops;
return (*__files)(CMD_OPEN, flags, name, mode);
}
static int
fileops(cmd, fd, buf, len)
int cmd, fd, len;
char * buf;
{
switch(cmd)
{
case CMD_OPEN: return op_open(buf, fd, len);
case CMD_READ: return op_read(fd, buf, len);
/*
case CMD_WRITE: return op_write(fd, buf, len);
case CMD_LSEEK: rv = op_lseek(fd, *(long*)buf, len);
(*(long*)buf) = rv;
if( rv == -1 ) return -1;
else return 0;
*/
case CMD_CLOSE: return op_close(fd);
}
errno=EINVAL;
return -1;
}
#define MAX_OPEN_FILES 5
ioblock _iob[MAX_OPEN_FILES];
static int
op_read(fd,buf,len)
int fd,len;
char * buf;
{
ioblock* cur = &_iob[fd];
int amount_read = 0;
int amount_left_in_buffer;
int amount_to_copy;
if (fd < 0 || fd >= MAX_OPEN_FILES || _iob[fd].block_read == 0)
{
errno = EBADF;
return -1;
}
while (len > 0)
{
/* pull in next block as required */
if (cur->amount_left <= 0)
{
int read_len = cur->block_read(cur,
cur->buffer,
(long) cur->offset / sizeof(cur->buffer)
);
#ifdef DEBUG
fprintf(stderr, "br: returned %d\n", read_len);
#endif
if (read_len <= 0)
break;
cur->amount_left = read_len;
}
if (cur->amount_left > len)
amount_to_copy = len;
else
amount_to_copy = cur->amount_left;
#ifdef DEBUG
fprintf(stderr, "r: len=%d, amount_left=%ld, offset=%ld, buf=%x\n",
len, cur->amount_left, cur->offset,
(int) cur->buffer[cur->offset % sizeof(cur->buffer)]);
#endif
memcpy(buf,
&cur->buffer[cur->offset % sizeof(cur->buffer)],
amount_to_copy);
amount_read += amount_to_copy;
len -= amount_to_copy;
cur->offset += amount_to_copy;
buf += amount_to_copy;
cur->amount_left -= amount_to_copy;
}
return amount_read;
}
/****************************************************************************/
static int
op_open(name, flags, mode)
char * name;
int flags, mode;
{
int fd;
ioblock* cur;
/*
* discover whether the iob has been initialised or not
*/
if (_iob[0].flags == 0)
{
_iob[0].flags = O_RDONLY;
_iob[1].flags = O_WRONLY;
_iob[2].flags = O_WRONLY;
}
/*
* discover next free iob
*/
for (fd = 3; fd < MAX_OPEN_FILES; ++fd)
{
if (_iob[fd].block_read == NULL && _iob[fd].block_write == NULL)
break;
}
if (fd >= MAX_OPEN_FILES)
{
errno = EMFILE; /* too many open files */
return -1;
}
/*
* try and find the file
*/
cur = &_iob[fd];
if (fsdos_open_file(cur, name, flags, mode) >= 0)
{
cur->amount_left = 0;
cur->offset = 0;
return fd;
}
cur->block_read = NULL; /* ensure that the file is closed */
cur->block_write = NULL;
errno = ENOENT;
return -1;
}
/****************************************************************************/
static int
op_close(fd)
int fd;
{
if (fd < 0 || fd >= MAX_OPEN_FILES || _iob[0].flags == 0)
{
errno = EBADF;
return -1;
}
else
{
ioblock* cur = &_iob[fd];
cur->close(cur);
cur->block_read = NULL;
cur->block_write = NULL;
cur->close = NULL;
cur->flags = 0;
return 0;
}
}
/****************************************************************************/
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