include/linux/pipe_fs_i.h

   1 #ifndef _LINUX_PIPE_FS_I_H
   2 #define _LINUX_PIPE_FS_I_H
   3
   4 struct pipe_inode_info {
   5         wait_queue_head_t wait;
   6         char *base;
   7         unsigned int start;
   8         unsigned int readers;
   9         unsigned int writers;
  10 };
  11
  12 /* Differs from PIPE_BUF in that PIPE_SIZE is the length of the actual
  13    memory allocation, whereas PIPE_BUF makes atomicity guarantees.  */
  14 #define PIPE_SIZE               PAGE_SIZE
  15
  16 #define PIPE_SEM(inode)         (&(inode).i_sem)
  17 #define PIPE_WAIT(inode)        (&(inode).i_pipe->wait)
  18 #define PIPE_BASE(inode)        ((inode).i_pipe->base)
  19 #define PIPE_START(inode)       ((inode).i_pipe->start)
  20 #define PIPE_LEN(inode)         ((inode).i_size)
  21 #define PIPE_READERS(inode)     ((inode).i_pipe->readers)
  22 #define PIPE_WRITERS(inode)     ((inode).i_pipe->writers)
  23
  24 #define PIPE_EMPTY(inode)       (PIPE_LEN(inode) == 0)
  25 #define PIPE_FULL(inode)        (PIPE_LEN(inode) == PIPE_SIZE)
  26 #define PIPE_FREE(inode)        (PIPE_SIZE - PIPE_LEN(inode))
  27 #define PIPE_END(inode) ((PIPE_START(inode) + PIPE_LEN(inode)) & (PIPE_SIZE-1))
  28 #define PIPE_MAX_RCHUNK(inode)  (PIPE_SIZE - PIPE_START(inode))
  29 #define PIPE_MAX_WCHUNK(inode)  (PIPE_SIZE - PIPE_END(inode))
  30
  31 #endif