/* pipe.h */

/* Definitions for a pipe device */

#ifndef PIPE_BUF_SIZE
#define PIPE_BUF_SIZE   20      /* Default size of a pipe buffer        */
#endif

/* state constants for a pipe pseudo device */

#define PIPE_FREE       0       /* Entry is not currently used          */
#define PIPE_OPEN       1       /* Entry is open for reading and writing*/
#define PIPE_EOF        2       /* Entry has been closed for writes, but*/
                                /*  remains open for reading until all  */
                                /*  chars have been read and EOF has    */
                                /*  returned                            */

struct  pipecblk {
        int32   pstate;         /* State of this pipe device            */
        byte    pbuf[PIPE_BUF_SIZE]; /* Buffer for the pipe             */
        int32   phead;          /* Index of next byte in pbuf to read   */
        int32   ptail;          /* Index of next byte in pbuf to write  */
        sid32   ppsem;          /* Producer semaphore for the pipe      */
        sid32   pcsem;          /* Consumer semaphore for the pipe      */
        did32   pdevid;         /* Device ID of this pseudo device      */
        int32   pavail;         /* Available characters during drain    */
};

extern  struct  pipecblk pipetab[];