#ifndef _IOVEC_H
#define _IOVEC_H

#include <stddef.h>
#include <stdbool.h>
#include <ringbuffer.h>

typedef struct {
	void *addr;
	size_t len;
} iovec_t;

typedef struct {
	iovec_t *iovec;
	size_t count;

	iovec_t *current;
	uintmax_t current_offset;

	uintmax_t total_offset;
	size_t total_size;
} iovec_iterator_t;

// checks if all iovec[x].addr is an userspace address
bool iovec_user_check(iovec_t *iovec, size_t count);

// returns the sum of the size of all iovecs
size_t iovec_size(iovec_t *iovec, size_t count);

// initializes an iovec iterator
void iovec_iterator_init(iovec_iterator_t *iovec_iterator, iovec_t *iovec, size_t count);

// skips skip_count bytes in the iovec iterator, returns the remaining number of bytes
size_t iovec_iterator_skip(iovec_iterator_t *iovec_iterator, size_t skip_count);

// sets the current offset of the iovec iterator to offset, returns the remaining number of bytes
size_t iovec_iterator_set(iovec_iterator_t *iovec_iterator, size_t offset);

// returns the offset that the iovec_iterator is on
size_t iovec_iterator_total_offset(iovec_iterator_t *iovec_iterator);

// copies byte_count bytes from the iovec_iterator into buffer
// NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail with EFAULT
int iovec_iterator_copy_to_buffer(iovec_iterator_t *iovec_iterator, void *buffer, size_t byte_count);

// copies byte_count bytes from buffer into the iovec_iterator
// NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail with EFAULT
int iovec_iterator_copy_from_buffer(iovec_iterator_t *iovec_iterator, void *buffer, size_t byte_count);

// sets byte_count bytes in the iovec_iterator to byte
// NOTE: the iovec can have userspace addresses. in this case, the memset can possibly fail with EFAULT
int iovec_iterator_memset(iovec_iterator_t *iovec_iterator, uint8_t byte, size_t byte_count);

// copies byte_count bytes from the iovec_iterator into the ringbuffer
// returns the number of bytes copied
// NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail by returning RINGBUFFER_USER_COPY_FAILED
size_t iovec_iterator_write_to_ringbuffer(iovec_iterator_t *iovec_iterator, ringbuffer_t *ringbuffer, size_t byte_count);

// copies byte_count bytes from the ringbuffer into the iovec_iterator
// returns the number of bytes copied
// NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail with RINGBUFFER_USER_COPY_FAILED
size_t iovec_iterator_read_from_ringbuffer(iovec_iterator_t *iovec_iterator, ringbuffer_t *ringbuffer, size_t byte_count);

// copies byte_count bytes from the ringbuffer into the iovec_iterator, without moving the ringbuffer read pointer
// returns the number of bytes copied
// NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail with RINGBUFFER_USER_COPY_FAILED
size_t iovec_iterator_peek_from_ringbuffer(iovec_iterator_t *iovec_iterator, ringbuffer_t *ringbuffer, size_t byte_count, uintmax_t ringbuffer_offset);

// returns the physical address of the next page in the iovec_iterator, adding a reference count and locking it for DMA. 
// The write bool controls whether the hint passed to mm_get_physical_address is a read or write (i.e. reading data from the page or 
// writing data to the page)
// sets the page_offset to the offset in the page, page_remaining to the remaining number of bytes in the page and page to the physical address of the page
// if no more pages in iovec_iterator, returns success with page being set to NULL
// fails with EFAULT if the page is not mapped
int iovec_iterator_next_page(iovec_iterator_t *iovec_iterator, size_t *page_offset, size_t *page_remaining, void **page, bool write);

#endif