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#include "errno.h"
#include "globals.h"
#include "util/debug.h"
#include "util/string.h"
#include "mm/kmalloc.h"
#include "mm/mobj.h"
#include "drivers/chardev.h"
#include "vm/anon.h"
#include "fs/vnode.h"
static ssize_t null_read(chardev_t *dev, size_t pos, void *buf, size_t count);
static ssize_t null_write(chardev_t *dev, size_t pos, const void *buf,
size_t count);
static ssize_t zero_read(chardev_t *dev, size_t pos, void *buf, size_t count);
static long zero_mmap(vnode_t *file, mobj_t **ret);
chardev_ops_t null_dev_ops = {.read = null_read,
.write = null_write,
.mmap = NULL,
.fill_pframe = NULL,
.flush_pframe = NULL};
chardev_ops_t zero_dev_ops = {.read = zero_read,
.write = null_write,
.mmap = zero_mmap,
.fill_pframe = NULL,
.flush_pframe = NULL};
/**
* The char device code needs to know about these mem devices, so create
* chardev_t's for null and zero, fill them in, and register them.
*
* Use kmalloc, MEM_NULL_DEVID, MEM_ZERO_DEVID, and chardev_register.
* See dev.h for device ids to use with MKDEVID.
*/
void memdevs_init()
{
NOT_YET_IMPLEMENTED("DRIVERS: memdevs_init");
}
/**
* Reads a given number of bytes from the null device into a
* buffer. Any read performed on the null device should read 0 bytes.
*
* @param dev the null device
* @param pos the offset to read from; should be ignored
* @param buf the buffer to read into
* @param count the maximum number of bytes to read
* @return the number of bytes read, which should be 0
*/
static ssize_t null_read(chardev_t *dev, size_t pos, void *buf, size_t count)
{
NOT_YET_IMPLEMENTED("DRIVERS: null_read");
return -ENOMEM;
}
/**
* Writes a given number of bytes to the null device from a
* buffer. Writing to the null device should _ALWAYS_ be successful
* and write the maximum number of bytes.
*
* @param dev the null device
* @param pos offset the offset to write to; should be ignored
* @param buf buffer to read from
* @param count the maximum number of bytes to write
* @return the number of bytes written, which should be `count`
*/
static ssize_t null_write(chardev_t *dev, size_t pos, const void *buf,
size_t count)
{
NOT_YET_IMPLEMENTED("DRIVERS: null_write");
return -ENOMEM;
}
/**
* Reads a given number of bytes from the zero device into a
* buffer. Any read from the zero device should be a series of zeros.
*
* @param dev the zero device
* @param pos the offset to start reading from; should be ignored
* @param buf the buffer to write to
* @param count the maximum number of bytes to read
* @return the number of bytes read. Hint: should always read the maximum
* number of bytes
*/
static ssize_t zero_read(chardev_t *dev, size_t pos, void *buf, size_t count)
{
NOT_YET_IMPLEMENTED("DRIVERS: zero_read");
return 0;
}
/**
* Unlike in s5fs_mmap(), you can't necessarily use the file's underlying mobj.
* Instead, you should simply provide an anonymous object to ret.
*/
static long zero_mmap(vnode_t *file, mobj_t **ret)
{
NOT_YET_IMPLEMENTED("VM: zero_mmap");
return -1;
}
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