156 lines
6.6 KiB
C
156 lines
6.6 KiB
C
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/*
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cdrfifo.c , Copyright 2006 Thomas Schmitt <scdbackup@gmx.net>
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A fd-to-fd or fd-to-memory fifo to be used within cdrskin or independently.
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By chaining of fifo objects, several fifos can be run simultaneously
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in fd-to-fd mode. Modes are controlled by parameter flag of
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Cdrfifo_try_to_work().
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Provided under GPL license within cdrskin and under BSD license elsewise.
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*/
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#ifndef Cdrfifo_headerfile_includeD
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#define Cdrfifo_headerfile_includeD
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/** The fifo buffer which will smoothen the data stream from data provider
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to data consumer. Although this is not a mandatory lifesaver for modern
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burners any more, a fifo can speed up burning of data which is delivered
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with varying bandwidths (e.g. compressed archives created on the fly
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or mkisofs running at its speed limit.).
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This structure is opaque to applications and may only be used via
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the Cdrfifo*() methods described in cdrfifo.h .
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*/
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struct CdrfifO;
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/** Create a fifo object.
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@param ff Returns the address of the new object.
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@param source_fd Filedescriptor opened to a readable data stream.
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@param dest_fd Filedescriptor opened to a writable data stream.
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To work with libburn, it needs to be attached to a
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struct burn_source object.
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@param chunk_size Size of buffer block for a single transaction (0=default)
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@param buffer_size Size of fifo buffer
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@param flag unused yet
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@return 1 on success, <=0 on failure
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*/
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int Cdrfifo_new(struct CdrfifO **ff, int source_fd, int dest_fd,
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int chunk_size, int buffer_size, int flag);
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/** Release from memory a fifo object previously created by Cdrfifo_new().
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@param ff The victim (gets returned as NULL, call can stand *ff==NULL)
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@param flag Bitfield for control purposes:
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bit0= do not close destination fd
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*/
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int Cdrfifo_destroy(struct CdrfifO **ff, int flag);
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/** Close any output fds */
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int Cdrfifo_close(struct CdrfifO *o, int flag);
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/** Close any output fds of o and its chain peers */
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int Cdrfifo_close_all(struct CdrfifO *o, int flag);
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int Cdrfifo_get_sizes(struct CdrfifO *o, int *chunk_size, int *buffer_size,
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int flag);
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/** Set a speed limit for buffer output.
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@param o The fifo object
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@param bytes_per_second >0 catch up slowdowns over the whole run time
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<0 catch up slowdowns only over one interval
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=0 disable speed limit
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*/
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int Cdrfifo_set_speed_limit(struct CdrfifO *o, double bytes_per_second,
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int flag);
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/** Set a fixed size for input in order to cut off any unwanted tail
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@param o The fifo object
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@param idx index for fds attached via Cdrfifo_attach_follow_up_fds(),
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first attached is 0, <0 directs limit to active fd limit
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(i.e. first track is -1, second track is 0, third is 1, ...)
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*/
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int Cdrfifo_set_fd_in_limit(struct CdrfifO *o, double fd_in_limit, int idx,
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int flag);
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int Cdrfifo_set_fds(struct CdrfifO *o, int source_fd, int dest_fd, int flag);
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int Cdrfifo_get_fds(struct CdrfifO *o, int *source_fd, int *dest_fd, int flag);
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/** Attach a further pair of input and output fd which will use the same
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fifo buffer when its predecessors are exhausted. Reading will start as
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soon as reading of the predecessor encounters EOF. Writing will start
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as soon as all pending predecessor data are written.
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@return index number of new item + 1, <=0 indicates error
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*/
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int Cdrfifo_attach_follow_up_fds(struct CdrfifO *o, int source_fd, int dest_fd,
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int flag);
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/** Attach a further fifo which shall be processed simultaneously with this
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one by Cdrfifo_try_to_work() in fd-to-fd mode.
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*/
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int Cdrfifo_attach_peer(struct CdrfifO *o, struct CdrfifO *next, int flag);
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/** Obtain buffer state.
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@param o The buffer object
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@param fill Returns the number of pending payload bytes in the buffer
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@param space Returns the number of unused buffer bytes
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@param flag unused yet
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@return -1=error , 0=inactive , 1=reading and writing ,
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2=reading ended (but still writing)
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*/
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int Cdrfifo_get_buffer_state(struct CdrfifO *o,int *fill,int *space,int flag);
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int Cdrfifo_get_counters(struct CdrfifO *o,
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double *in_counter, double *out_counter, int flag);
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/** reads min_fill and begins measurement interval for next min_fill */
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int Cdrfifo_next_interval(struct CdrfifO *o, int *min_fill, int flag);
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int Cdrfifo_get_min_fill(struct CdrfifO *o, int *total_min_fill,
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int *interval_min_fill, int flag);
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int Cdrfifo_get_cdr_counters(struct CdrfifO *o,
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double *put_counter, double *get_counter,
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double *empty_counter, double *full_counter,
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int flag);
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/** Check for pending data at the fifo's source file descriptor and wether the
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fifo is ready to take them. Simultaneously check the buffer for existing
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data and the destination fd for readiness to accept some. If so, a small
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chunk of data is transfered to and/or from the fifo.
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This is done for the given fifo object and all members of its next-chain.
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The check and transactions are repeated until a given timespan has elapsed.
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libburn applications call this function in the burn loop instead of sleep().
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It may also be used instead of read(). Then it returns as soon as an output
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transaction would be performed. See flag:bit2.
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@param o The fifo object
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@param wait_usec The time in microseconds after which the function shall
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return.
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@param reply_buffer with bit2: Returns write-ready buffer chunk and must
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be able to take at least chunk_size bytes
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@param reply_count with bit2: Returns number of writeable bytes in reply_pt
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@param flag Bitfield for control purposes:
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bit0= Enable debug pacifier (same with Cdrfifo_debuG)
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bit1= Do not write, just fill buffer
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bit2= fd-to-memory mode (else fd-to-fd mode):
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Rather than writing a chunk return it and its size.
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No simultaneous processing of chained fifos.
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bit3= With bit2: do not check destination fd for readiness
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@return <0 = error , 0 = idle , 1 = did some work , 2 = all work is done
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*/
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int Cdrfifo_try_to_work(struct CdrfifO *o, int wait_usec,
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char *reply_buffer, int *reply_count, int flag);
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/** Fill the fifo as far as possible without writing to destination fd
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@return 1 on success, <=0 on failure
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*/
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int Cdrfifo_fill(struct CdrfifO *o, int flag);
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#endif /* Cdrfifo_headerfile_includeD */
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