os_kernel_lab/code/lab8/kern/fs/iobuf.h

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2012-08-22 12:32:13 +08:00
#ifndef __KERN_FS_IOBUF_H__
#define __KERN_FS_IOBUF_H__
#include <defs.h>
/*
* iobuf is a buffer Rd/Wr status record
*/
struct iobuf {
void *io_base; // the base addr of buffer (used for Rd/Wr)
off_t io_offset; // current Rd/Wr position in buffer, will have been incremented by the amount transferred
size_t io_len; // the length of buffer (used for Rd/Wr)
size_t io_resid; // current resident length need to Rd/Wr, will have been decremented by the amount transferred.
};
#define iobuf_used(iob) ((size_t)((iob)->io_len - (iob)->io_resid))
struct iobuf *iobuf_init(struct iobuf *iob, void *base, size_t len, off_t offset);
int iobuf_move(struct iobuf *iob, void *data, size_t len, bool m2b, size_t *copiedp);
int iobuf_move_zeros(struct iobuf *iob, size_t len, size_t *copiedp);
void iobuf_skip(struct iobuf *iob, size_t n);
#endif /* !__KERN_FS_IOBUF_H__ */