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vlc/include/vlc_block.h

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/*****************************************************************************
* vlc_block.h: Data blocks management functions
*****************************************************************************
* Copyright (C) 2003 VLC authors and VideoLAN
* $Id$
*
* Authors: Laurent Aimar <fenrir@via.ecp.fr>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
*****************************************************************************/
#ifndef VLC_BLOCK_H
#define VLC_BLOCK_H 1
/**
* \defgroup block Data blocks
* \ingroup input
*
* Blocks of binary data.
*
* @ref block_t is a generic structure to represent a binary blob within VLC.
* The primary goal of the structure is to avoid memory copying as data is
* passed around. It is notably used between the \ref demux, the packetizer
* (if present) and the \ref decoder, and for audio, between the \ref decoder,
* the audio filters, and the \ref audio_output.
*
* @{
* \file
* Data block definition and functions
*/
#include <sys/types.h> /* for ssize_t */
/****************************************************************************
* block:
****************************************************************************
* - i_flags may not always be set (ie could be 0, even for a key frame
* it depends where you receive the buffer (before/after a packetizer
* and the demux/packetizer implementations.
* - i_dts/i_pts could be VLC_TS_INVALID, it means no pts/dts
* - i_length: length in microseond of the packet, can be null except in the
* sout where it is mandatory.
*
* - i_buffer number of valid data pointed by p_buffer
* you can freely decrease it but never increase it yourself
* (use block_Realloc)
* - p_buffer: pointer over datas. You should never overwrite it, you can
* only incremment it to skip datas, in others cases use block_Realloc
* (don't duplicate yourself in a bigger buffer, block_Realloc is
* optimised for preheader/postdatas increase)
****************************************************************************/
/** The content doesn't follow the last block, possible some blocks in between
* have been lost */
#define BLOCK_FLAG_DISCONTINUITY 0x0001
/** Intra frame */
#define BLOCK_FLAG_TYPE_I 0x0002
/** Inter frame with backward reference only */
#define BLOCK_FLAG_TYPE_P 0x0004
/** Inter frame with backward and forward reference */
#define BLOCK_FLAG_TYPE_B 0x0008
/** For inter frame when you don't know the real type */
#define BLOCK_FLAG_TYPE_PB 0x0010
/** Warn that this block is a header one */
#define BLOCK_FLAG_HEADER 0x0020
/** This block contains the last part of a sequence */
#define BLOCK_FLAG_END_OF_SEQUENCE 0x0040
/** This block contains a clock reference */
#define BLOCK_FLAG_CLOCK 0x0080
/** This block is scrambled */
#define BLOCK_FLAG_SCRAMBLED 0x0100
/** This block has to be decoded but not be displayed */
#define BLOCK_FLAG_PREROLL 0x0200
/** This block is corrupted and/or there is data loss */
#define BLOCK_FLAG_CORRUPTED 0x0400
/** This block contains an interlaced picture with top field stored first */
#define BLOCK_FLAG_TOP_FIELD_FIRST 0x0800
/** This block contains an interlaced picture with bottom field stored first */
#define BLOCK_FLAG_BOTTOM_FIELD_FIRST 0x1000
/** This block contains a single field from interlaced picture. */
#define BLOCK_FLAG_SINGLE_FIELD 0x2000
/** This block contains an interlaced picture */
#define BLOCK_FLAG_INTERLACED_MASK \
(BLOCK_FLAG_TOP_FIELD_FIRST|BLOCK_FLAG_BOTTOM_FIELD_FIRST|BLOCK_FLAG_SINGLE_FIELD)
#define BLOCK_FLAG_TYPE_MASK \
(BLOCK_FLAG_TYPE_I|BLOCK_FLAG_TYPE_P|BLOCK_FLAG_TYPE_B|BLOCK_FLAG_TYPE_PB)
/* These are for input core private usage only */
#define BLOCK_FLAG_CORE_PRIVATE_MASK 0x00ff0000
#define BLOCK_FLAG_CORE_PRIVATE_SHIFT 16
/* These are for module private usage only */
#define BLOCK_FLAG_PRIVATE_MASK 0xff000000
#define BLOCK_FLAG_PRIVATE_SHIFT 24
typedef void (*block_free_t) (block_t *);
struct block_t
{
block_t *p_next;
uint8_t *p_buffer; /**< Payload start */
size_t i_buffer; /**< Payload length */
uint8_t *p_start; /**< Buffer start */
size_t i_size; /**< Buffer total size */
uint32_t i_flags;
unsigned i_nb_samples; /* Used for audio */
mtime_t i_pts;
mtime_t i_dts;
mtime_t i_length;
/* Rudimentary support for overloading block (de)allocation. */
block_free_t pf_release;
};
VLC_API void block_Init( block_t *, void *, size_t );
/**
* Allocates a block.
*
* Creates a new block with the requested size.
* The block must be released with block_Release().
*
* @param size size in bytes (possibly zero)
* @return the created block, or NULL on memory error.
*/
VLC_API block_t *block_Alloc(size_t size) VLC_USED VLC_MALLOC;
VLC_API block_t *block_TryRealloc(block_t *, ssize_t pre, size_t body) VLC_USED;
/**
* Reallocates a block.
*
* This function expands, shrinks or moves a data block.
* In many cases, this function can return without any memory allocation by
* reusing spare buffer space. Otherwise, a new block is created and data is
* copied.
*
* @param pre count of bytes to prepend if positive,
* count of leading bytes to discard if negative
* @param body new bytes size of the block
*
* @return the reallocated block on succes, NULL on error.
*
* @note Skipping leading bytes can be achieved directly by subtracting from
* block_t.i_buffer and adding block_t.p_buffer.
* @note Discard trailing bytes can be achieved directly by subtracting from
* block_t.i_buffer.
* @note On error, the block is discarded.
* To avoid that, use block_TryRealloc() instead.
*/
VLC_API block_t *block_Realloc(block_t *, ssize_t pre, size_t body) VLC_USED;
/**
* Releases a block.
*
* This function works for any @ref block_t block, regardless of the way it was
* allocated.
*
* @note
* If the block is in a chain, this function does <b>not</b> release any
* subsequent block in the chain. Use block_ChainRelease() for that purpose.
*
* @param block block to release (cannot be NULL)
*/
static inline void block_Release(block_t *block)
{
block->pf_release(block);
}
static inline void block_CopyProperties( block_t *dst, block_t *src )
{
dst->i_flags = src->i_flags;
dst->i_nb_samples = src->i_nb_samples;
dst->i_dts = src->i_dts;
dst->i_pts = src->i_pts;
dst->i_length = src->i_length;
}
/**
* Duplicates a block.
*
* Creates a writeable duplicate of a block.
*
* @return the duplicate on success, NULL on error.
*/
VLC_USED
static inline block_t *block_Duplicate( block_t *p_block )
{
block_t *p_dup = block_Alloc( p_block->i_buffer );
if( p_dup == NULL )
return NULL;
block_CopyProperties( p_dup, p_block );
memcpy( p_dup->p_buffer, p_block->p_buffer, p_block->i_buffer );
return p_dup;
}
/**
* Wraps heap in a block.
*
* Creates a @ref block_t out of an existing heap allocation.
* This is provided by LibVLC so that manually heap-allocated blocks can safely
* be deallocated even after the origin plugin has been unloaded from memory.
*
* When block_Release() is called, VLC will free() the specified pointer.
*
* @param addr base address of the heap allocation (will be free()'d)
* @param length bytes length of the heap allocation
* @return NULL in case of error (ptr free()'d in that case), or a valid
* block_t pointer.
*/
VLC_API block_t *block_heap_Alloc(void *, size_t) VLC_USED VLC_MALLOC;
/**
* Wraps a memory mapping in a block
*
* Creates a @ref block_t from a virtual address memory mapping (mmap).
* This is provided by LibVLC so that mmap blocks can safely be deallocated
* even after the allocating plugin has been unloaded from memory.
*
* @param addr base address of the mapping (as returned by mmap)
* @param length length (bytes) of the mapping (as passed to mmap)
* @return NULL if addr is MAP_FAILED, or an error occurred (in the later
* case, munmap(addr, length) is invoked before returning).
*/
VLC_API block_t *block_mmap_Alloc(void *addr, size_t length) VLC_USED VLC_MALLOC;
/**
* Wraps a System V memory segment in a block
*
* Creates a @ref block_t from a System V shared memory segment (shmget()).
* This is provided by LibVLC so that segments can safely be deallocated
* even after the allocating plugin has been unloaded from memory.
*
* @param addr base address of the segment (as returned by shmat())
* @param length length (bytes) of the segment (as passed to shmget())
* @return NULL if an error occurred (in that case, shmdt(addr) is invoked
* before returning NULL).
*/
VLC_API block_t * block_shm_Alloc(void *addr, size_t length) VLC_USED VLC_MALLOC;
/**
* Maps a file handle in memory.
*
* Loads a file into a block of memory through a file descriptor.
* If possible a private file mapping is created. Otherwise, the file is read
* normally. This function is a cancellation point.
*
* @note On 32-bits platforms,
* this function will not work for very large files,
* due to memory space constraints.
*
* @param fd file descriptor to load from
* @param write If true, request a read/write private mapping.
* If false, request a read-only potentially shared mapping.
*
* @return a new block with the file content at p_buffer, and file length at
* i_buffer (release it with block_Release()), or NULL upon error (see errno).
*/
VLC_API block_t *block_File(int fd, bool write) VLC_USED VLC_MALLOC;
/**
* Maps a file in memory.
*
* Loads a file into a block of memory from a path to the file.
* See also block_File().
*
* @param write If true, request a read/write private mapping.
* If false, request a read-only potentially shared mapping.
*/
VLC_API block_t *block_FilePath(const char *, bool write) VLC_USED VLC_MALLOC;
static inline void block_Cleanup (void *block)
{
block_Release ((block_t *)block);
}
#define block_cleanup_push( block ) vlc_cleanup_push (block_Cleanup, block)
/**
* \defgroup block_fifo Block chain
* @{
*/
/****************************************************************************
* Chains of blocks functions helper
****************************************************************************
* - block_ChainAppend : append a block to the last block of a chain. Try to
* avoid using with a lot of data as it's really slow, prefer
* block_ChainLastAppend, p_block can be NULL
* - block_ChainLastAppend : use a pointer over a pointer to the next blocks,
* and update it.
* - block_ChainRelease : release a chain of block
* - block_ChainExtract : extract data from a chain, return real bytes counts
* - block_ChainGather : gather a chain, free it and return one block.
****************************************************************************/
static inline void block_ChainAppend( block_t **pp_list, block_t *p_block )
{
if( *pp_list == NULL )
{
*pp_list = p_block;
}
else
{
block_t *p = *pp_list;
while( p->p_next ) p = p->p_next;
p->p_next = p_block;
}
}
static inline void block_ChainLastAppend( block_t ***ppp_last, block_t *p_block )
{
block_t *p_last = p_block;
**ppp_last = p_block;
while( p_last->p_next ) p_last = p_last->p_next;
*ppp_last = &p_last->p_next;
}
static inline void block_ChainRelease( block_t *p_block )
{
while( p_block )
{
block_t *p_next = p_block->p_next;
block_Release( p_block );
p_block = p_next;
}
}
static size_t block_ChainExtract( block_t *p_list, void *p_data, size_t i_max )
{
size_t i_total = 0;
uint8_t *p = (uint8_t*)p_data;
while( p_list && i_max )
{
size_t i_copy = __MIN( i_max, p_list->i_buffer );
memcpy( p, p_list->p_buffer, i_copy );
i_max -= i_copy;
i_total += i_copy;
p += i_copy;
p_list = p_list->p_next;
}
return i_total;
}
static inline void block_ChainProperties( block_t *p_list, int *pi_count, size_t *pi_size, mtime_t *pi_length )
{
size_t i_size = 0;
mtime_t i_length = 0;
int i_count = 0;
while( p_list )
{
i_size += p_list->i_buffer;
i_length += p_list->i_length;
i_count++;
p_list = p_list->p_next;
}
if( pi_size )
*pi_size = i_size;
if( pi_length )
*pi_length = i_length;
if( pi_count )
*pi_count = i_count;
}
static inline block_t *block_ChainGather( block_t *p_list )
{
size_t i_total = 0;
mtime_t i_length = 0;
block_t *g;
if( p_list->p_next == NULL )
return p_list; /* Already gathered */
block_ChainProperties( p_list, NULL, &i_total, &i_length );
g = block_Alloc( i_total );
if( !g )
return NULL;
block_ChainExtract( p_list, g->p_buffer, g->i_buffer );
g->i_flags = p_list->i_flags;
g->i_pts = p_list->i_pts;
g->i_dts = p_list->i_dts;
g->i_length = i_length;
/* free p_list */
block_ChainRelease( p_list );
return g;
}
/**
* @}
* \defgroup fifo Block FIFO
* Thread-safe block queue functions
* @{
*/
/**
* Creates a thread-safe FIFO queue of blocks.
*
* See also block_FifoPut() and block_FifoGet().
* The created queue must be released with block_FifoRelease().
*
* @return the FIFO or NULL on memory error
*/
VLC_API block_fifo_t *block_FifoNew(void) VLC_USED VLC_MALLOC;
/**
* Destroys a FIFO created by block_FifoNew().
*
* @note Any queued blocks are also destroyed.
* @warning No other threads may be using the FIFO when this function is
* called. Otherwise, undefined behaviour will occur.
*/
VLC_API void block_FifoRelease(block_fifo_t *);
/**
* Clears all blocks in a FIFO.
*/
VLC_API void block_FifoEmpty(block_fifo_t *);
/**
* Immediately queue one block at the end of a FIFO.
*
* @param fifo queue
* @param block head of a block list to queue (may be NULL)
*/
VLC_API void block_FifoPut(block_fifo_t *fifo, block_t *block);
/**
* Dequeue the first block from the FIFO. If necessary, wait until there is
* one block in the queue. This function is (always) cancellation point.
*
* @return a valid block
*/
VLC_API block_t *block_FifoGet(block_fifo_t *) VLC_USED;
/**
* Peeks the first block in the FIFO.
*
* @warning This function leaves the block in the FIFO.
* You need to protect against concurrent threads who could dequeue the block.
* Preferably, there should be only one thread reading from the FIFO.
*
* @warning This function is undefined if the FIFO is empty.
*
* @return a valid block.
*/
VLC_API block_t *block_FifoShow(block_fifo_t *);
size_t block_FifoSize(block_fifo_t *) VLC_USED VLC_DEPRECATED;
VLC_API size_t block_FifoCount(block_fifo_t *) VLC_USED VLC_DEPRECATED;
typedef struct block_fifo_t vlc_fifo_t;
/**
* Locks a block FIFO.
*
* No more than one thread can lock the FIFO at any given
* time, and no other thread can modify the FIFO while it is locked.
* vlc_fifo_Unlock() releases the lock.
*
* @note If the FIFO is already locked by another thread, this function waits.
* This function is not a cancellation point.
*
* @warning Recursively locking a single FIFO is undefined. Locking more than
* one FIFO at a time may lead to lock inversion; mind the locking order.
*/
VLC_API void vlc_fifo_Lock(vlc_fifo_t *);
/**
* Unlocks a block FIFO.
*
* The calling thread must have locked the FIFO previously with
* vlc_fifo_Lock(). Otherwise, the behaviour is undefined.
*
* @note This function is not a cancellation point.
*/
VLC_API void vlc_fifo_Unlock(vlc_fifo_t *);
/**
* Wakes up one thread waiting on the FIFO, if any.
*
* @note This function is not a cancellation point.
*
* @warning For race-free operations, the FIFO should be locked by the calling
* thread. The function can be called on a unlocked FIFO however.
*/
VLC_API void vlc_fifo_Signal(vlc_fifo_t *);
/**
* Waits on the FIFO.
*
* Atomically unlocks the FIFO and waits until one thread signals the FIFO,
* then locks the FIFO again. A signal can be sent by queueing a block to the
* previously empty FIFO or by calling vlc_fifo_Signal() directly.
* This function may also return spuriously at any moment.
*
* @note This function is a cancellation point. In case of cancellation, the
* the FIFO will be locked before cancellation cleanup handlers are processed.
*/
VLC_API void vlc_fifo_Wait(vlc_fifo_t *);
VLC_API void vlc_fifo_WaitCond(vlc_fifo_t *, vlc_cond_t *);
/**
* Timed variant of vlc_fifo_WaitCond().
*
* Atomically unlocks the FIFO and waits until one thread signals the FIFO up
* to a certain date, then locks the FIFO again. See vlc_fifo_Wait().
*/
int vlc_fifo_TimedWaitCond(vlc_fifo_t *, vlc_cond_t *, mtime_t);
/**
* Queues a linked-list of blocks into a locked FIFO.
*
* @param block the head of the list of blocks
* (if NULL, this function has no effects)
*
* @note This function is not a cancellation point.
*
* @warning The FIFO must be locked by the calling thread using
* vlc_fifo_Lock(). Otherwise behaviour is undefined.
*/
VLC_API void vlc_fifo_QueueUnlocked(vlc_fifo_t *, block_t *);
/**
* Dequeues the first block from a locked FIFO, if any.
*
* @note This function is not a cancellation point.
*
* @warning The FIFO must be locked by the calling thread using
* vlc_fifo_Lock(). Otherwise behaviour is undefined.
*
* @return the first block in the FIFO or NULL if the FIFO is empty
*/
VLC_API block_t *vlc_fifo_DequeueUnlocked(vlc_fifo_t *) VLC_USED;
/**
* Dequeues the all blocks from a locked FIFO.
*
* This is equivalent to calling vlc_fifo_DequeueUnlocked() repeatedly until
* the FIFO is emptied, but this function is much faster.
*
* @note This function is not a cancellation point.
*
* @warning The FIFO must be locked by the calling thread using
* vlc_fifo_Lock(). Otherwise behaviour is undefined.
*
* @return a linked-list of all blocks in the FIFO (possibly NULL)
*/
VLC_API block_t *vlc_fifo_DequeueAllUnlocked(vlc_fifo_t *) VLC_USED;
/**
* Counts blocks in a FIFO.
*
* Checks how many blocks are queued in a locked FIFO.
*
* @note This function is not cancellation point.
*
* @warning The FIFO must be locked by the calling thread using
* vlc_fifo_Lock(). Otherwise behaviour is undefined.
*
* @return the number of blocks in the FIFO (zero if it is empty)
*/
VLC_API size_t vlc_fifo_GetCount(const vlc_fifo_t *) VLC_USED;
/**
* Counts bytes in a FIFO.
*
* Checks how many bytes are queued in a locked FIFO.
*
* @note This function is not cancellation point.
*
* @warning The FIFO must be locked by the calling thread using
* vlc_fifo_Lock(). Otherwise behaviour is undefined.
*
* @return the total number of bytes
*
* @note Zero bytes does not necessarily mean that the FIFO is empty since
* a block could contain zero bytes. Use vlc_fifo_GetCount() to determine if
* a FIFO is empty.
*/
VLC_API size_t vlc_fifo_GetBytes(const vlc_fifo_t *) VLC_USED;
VLC_USED static inline bool vlc_fifo_IsEmpty(const vlc_fifo_t *fifo)
{
return vlc_fifo_GetCount(fifo) == 0;
}
static inline void vlc_fifo_Cleanup(void *fifo)
{
vlc_fifo_Unlock((vlc_fifo_t *)fifo);
}
#define vlc_fifo_CleanupPush(fifo) vlc_cleanup_push(vlc_fifo_Cleanup, fifo)
/** @} */
/** @} */
#endif /* VLC_BLOCK_H */
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