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#ifndef _LINUX_SCATTERLIST_H
#define _LINUX_SCATTERLIST_H
#include <linux/bug.h>
#include <linux/slab.h>
struct scatterlist {
unsigned long page_link;
unsigned int offset;
unsigned int length;
};
#define sg_is_chain(sg) ((sg)->page_link & 0x01)
#define sg_is_last(sg) ((sg)->page_link & 0x02)
#define sg_chain_ptr(sg) \
((struct scatterlist *) ((sg)->page_link & ~0x03))
static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
{
unsigned long page_link = sg->page_link & 0x3;
/*
* In order for the low bit stealing approach to work, pages
* must be aligned at a 32-bit boundary as a minimum.
*/
BUG_ON((unsigned long) page & 0x03);
sg->page_link = page_link | (unsigned long) page;
}
static inline void sg_set_page(struct scatterlist *sg, struct page *page,
unsigned int len, unsigned int offset)
{
sg_assign_page(sg, page);
sg->offset = offset;
sg->length = len;
}
static inline struct page *sg_page(struct scatterlist *sg)
{
return (struct page *)((sg)->page_link & ~0x3);
}
static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
unsigned int buflen)
{
sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
}
static inline struct scatterlist *sg_next(struct scatterlist *sg)
{
if (sg_is_last(sg))
return NULL;
sg++;
if (unlikely(sg_is_chain(sg)))
sg = sg_chain_ptr(sg);
return sg;
}
#define for_each_sg(sglist, sg, nr, __i) \
for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
struct scatterlist *sgl)
{
/*
* offset and length are unused for chain entry. Clear them.
*/
prv[prv_nents - 1].offset = 0;
prv[prv_nents - 1].length = 0;
/*
* Set lowest bit to indicate a link pointer, and make sure to clear
* the termination bit if it happens to be set.
*/
prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02;
}
static inline void sg_mark_end(struct scatterlist *sg)
{
sg->page_link |= 0x02;
sg->page_link &= ~0x01;
}
static inline void sg_unmark_end(struct scatterlist *sg)
{
sg->page_link &= ~0x02;
}
static inline void *sg_virt(struct scatterlist *sg)
{
return page_address(sg_page(sg)) + sg->offset;
}
static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents)
{
memset(sgl, 0, sizeof(*sgl) * nents);
sg_mark_end(&sgl[nents - 1]);
}
static inline void sg_init_one(struct scatterlist *sg, const void *buf,
unsigned int buflen)
{
sg_init_table(sg, 1);
sg_set_buf(sg, buf, buflen);
}
#endif /* _LINUX_SCATTERLIST_H */
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