Line-Following-Robot/Input/Externals/raspicam-master/dependencies/mmal/mmal_pool.h

/*
Copyright (c) 2012, Broadcom Europe Ltd
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      names of its contributors may be used to endorse or promote products
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*/

#ifndef MMAL_POOL_H
#define MMAL_POOL_H

#ifdef __cplusplus
extern "C" {
#endif

/** \defgroup MmalPool Pools of buffer headers
 * A pool of buffer headers is composed of a queue (\ref MMAL_QUEUE_T) and a user
 * specified number of buffer headers (\ref MMAL_BUFFER_HEADER_T). */
/* @{ */

#include "mmal_queue.h"

/** Definition of a pool */
typedef struct MMAL_POOL_T
{
   MMAL_QUEUE_T *queue;             /**< Queue used by the pool */
   uint32_t headers_num;            /**< Number of buffer headers in the pool */
   MMAL_BUFFER_HEADER_T **header;   /**< Array of buffer headers belonging to the pool */
} MMAL_POOL_T;

/** Allocator alloc prototype
 *
 * @param context The context pointer passed in on pool creation.
 * @param size    The size of the allocation required, in bytes.
 * @return The pointer to the newly allocated memory, or NULL on failure.
 */
typedef void *(*mmal_pool_allocator_alloc_t)(void *context, uint32_t size);
/** Allocator free prototype
 *
 * @param context The context pointer passed in on pool creation.
 * @param mem     The pointer to the memory to be released.
 */
typedef void (*mmal_pool_allocator_free_t)(void *context, void *mem);

/** Create a pool of MMAL_BUFFER_HEADER_T.
 * After allocation, all allocated buffer headers will have been added to the queue.
 *
 * It is valid to create a pool with no buffer headers, or with zero size payload buffers.
 * The mmal_pool_resize() function can be used to increase or decrease the number of buffer
 * headers, or the size of the payload buffers, after creation of the pool.
 *
 * The payload buffers may also be allocated independently by the client, and assigned
 * to the buffer headers, but it will be the responsibility of the client to deal with
 * resizing and releasing the memory. It is recommended that mmal_pool_create_with_allocator()
 * is used in this case, supplying allocator function pointers that will be used as
 * necessary by MMAL.
 *
 * @param headers      Number of buffer headers to be allocated with the pool.
 * @param payload_size Size of the payload buffer that will be allocated in 
 *                     each of the buffer headers.
 * @return Pointer to the newly created pool or NULL on failure.
 */
MMAL_POOL_T *mmal_pool_create(unsigned int headers, uint32_t payload_size);

/** Create a pool of MMAL_BUFFER_HEADER_T.
 * After allocation, all allocated buffer headers will have been added to the queue.
 *
 * It is valid to create a pool with no buffer headers, or with zero size payload buffers.
 * The mmal_pool_resize() function can be used to increase or decrease the number of buffer
 * headers, or the size of the payload buffers, after creation of the pool. The allocators
 * passed during creation shall be used when resizing the payload buffers.
 *
 * @param headers      Number of buffer headers to be allocated with the pool.
 * @param payload_size Size of the payload buffer that will be allocated in
 *                     each of the buffer headers.
 * @param allocator_context Pointer to the context of the allocator.
 * @param allocator_alloc   Function pointer for the alloc call of the allocator.
 * @param allocator_free    Function pointer for the free call of the allocator.
 *
 * @return Pointer to the newly created pool or NULL on failure.
 */
MMAL_POOL_T *mmal_pool_create_with_allocator(unsigned int headers, uint32_t payload_size,
                              void *allocator_context, mmal_pool_allocator_alloc_t allocator_alloc,
                              mmal_pool_allocator_free_t allocator_free);

/** Destroy a pool of MMAL_BUFFER_HEADER_T.
 * This will also deallocate all of the memory which was allocated when creating or
 * resizing the pool.
 *
 * If payload buffers have been allocated independently by the client, they should be
 * released prior to calling this function. If the client provided allocator functions,
 * the allocator_free function shall be called for each payload buffer.
 *
 * @param pool  Pointer to a pool
 */
void mmal_pool_destroy(MMAL_POOL_T *pool);

/** Resize a pool of MMAL_BUFFER_HEADER_T.
 * This allows modifying either the number of allocated buffers, the payload size or both at the
 * same time.
 *
 * @param pool         Pointer to the pool
 * @param headers      New number of buffer headers to be allocated in the pool.
 *                     It is not valid to pass zero for the number of buffers.
 * @param payload_size Size of the payload buffer that will be allocated in
 *                     each of the buffer headers.
 *                     If this is set to 0, all payload buffers shall be released.
 * @return MMAL_SUCCESS or an error on failure.
 */
MMAL_STATUS_T mmal_pool_resize(MMAL_POOL_T *pool, unsigned int headers, uint32_t payload_size);

/** Definition of the callback used by a pool to signal back to the user that a buffer header
 * has been released back to the pool.
 *
 * @param pool       Pointer to the pool
 * @param buffer     Buffer header just released
 * @param userdata   User specific data passed in when setting the callback
 * @return True to have the buffer header put back in the pool's queue, false if the buffer
 *          header has been taken within the callback.
 */
typedef MMAL_BOOL_T (*MMAL_POOL_BH_CB_T)(MMAL_POOL_T *pool, MMAL_BUFFER_HEADER_T *buffer, void *userdata);

/** Set a buffer header release callback to the pool.
 * Each time a buffer header is released to the pool, the callback will be triggered.
 *
 * @param pool     Pointer to a pool
 * @param cb       Callback function
 * @param userdata User specific data which will be passed with each callback
 */
void mmal_pool_callback_set(MMAL_POOL_T *pool, MMAL_POOL_BH_CB_T cb, void *userdata);

/** Set a pre-release callback for all buffer headers in the pool.
 * Each time a buffer header is about to be released to the pool, the callback
 * will be triggered.
 *
 * @param pool     Pointer to the pool
 * @param cb       Pre-release callback function
 * @param userdata User-specific data passed back with each callback
 */
void mmal_pool_pre_release_callback_set(MMAL_POOL_T *pool, MMAL_BH_PRE_RELEASE_CB_T cb, void *userdata);

/* @} */

#ifdef __cplusplus
}
#endif

#endif /* MMAL_POOL_H */