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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group. *
* All rights reserved. *
* *
* This file is part of HDF5. The full HDF5 copyright notice, including *
* terms governing use, modification, and redistribution, is contained in *
* the COPYING file, which can be found at the root of the source code *
* distribution tree, or in https://www.hdfgroup.org/licenses. *
* If you do not have access to either file, you may request a copy from *
* help@hdfgroup.org. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*-------------------------------------------------------------------------
*
* Created: H5WB.c
*
* Purpose: Implements the "wrapped buffer" code for wrapping
* an existing [statically sized] buffer, in order to
* avoid lots of memory allocation calls.
*
*-------------------------------------------------------------------------
*/
/****************/
/* Module Setup */
/****************/
/***********/
/* Headers */
/***********/
#include "H5private.h" /* Generic Functions */
#include "H5Eprivate.h" /* Error handling */
#include "H5FLprivate.h" /* Free Lists */
#include "H5WBprivate.h" /* Wrapped Buffers */
/****************/
/* Local Macros */
/****************/
/******************/
/* Local Typedefs */
/******************/
/********************/
/* Package Typedefs */
/********************/
/* Typedef for buffer wrapper */
struct H5WB_t {
void *wrapped_buf; /* Pointer to wrapped buffer */
size_t wrapped_size; /* Size of wrapped buffer */
void *actual_buf; /* Pointer to actual buffer */
size_t actual_size; /* Size of actual buffer used */
size_t alloc_size; /* Size of actual buffer allocated */
};
/********************/
/* Local Prototypes */
/********************/
/*********************/
/* Package Variables */
/*********************/
/*****************************/
/* Library Private Variables */
/*****************************/
/*******************/
/* Local Variables */
/*******************/
/* Declare a free list to manage the H5WB_t struct */
H5FL_DEFINE_STATIC(H5WB_t);
/* Declare a free list to manage the extra buffer information */
H5FL_BLK_DEFINE_STATIC(extra_buf);
/*-------------------------------------------------------------------------
* Function: H5WB_wrap
*
* Purpose: Wraps an existing [possibly static] buffer
*
* Return: Pointer to buffer wrapper info on success
* NULL on failure
*
*-------------------------------------------------------------------------
*/
H5WB_t *
H5WB_wrap(void *buf, size_t buf_size)
{
H5WB_t *wb = NULL; /* Wrapped buffer info */
H5WB_t *ret_value; /* Return value */
FUNC_ENTER_NOAPI(NULL)
/*
* Check arguments.
*/
assert(buf);
assert(buf_size);
/* Create wrapped buffer info */
if (NULL == (wb = H5FL_MALLOC(H5WB_t)))
HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for wrapped buffer info");
/* Wrap buffer given */
wb->wrapped_buf = buf;
wb->wrapped_size = buf_size;
/* No actual buffer yet */
wb->actual_buf = NULL;
wb->actual_size = 0;
wb->alloc_size = 0;
/* Set the return value */
ret_value = wb;
done:
/* Release resources on error */
if (!ret_value && wb)
wb = H5FL_FREE(H5WB_t, wb);
FUNC_LEAVE_NOAPI(ret_value)
} /* end H5WB_wrap() */
/*-------------------------------------------------------------------------
* Function: H5WB_actual
*
* Purpose: Get the pointer to an "actual" buffer, of at least a certain
* size.
*
* Return: Pointer to buffer pointer on success
* NULL on failure
*
*-------------------------------------------------------------------------
*/
void *
H5WB_actual(H5WB_t *wb, size_t need)
{
void *ret_value; /* Return value */
FUNC_ENTER_NOAPI(NULL)
/*
* Check arguments.
*/
assert(wb);
assert(wb->wrapped_buf);
/* Check for previously allocated buffer */
if (wb->actual_buf && wb->actual_buf != wb->wrapped_buf) {
/* Sanity check */
assert(wb->actual_size > wb->wrapped_size);
/* Check if we can reuse existing buffer */
if (need <= wb->alloc_size)
HGOTO_DONE(wb->actual_buf);
/* Can't reuse existing buffer, free it and proceed */
else
wb->actual_buf = H5FL_BLK_FREE(extra_buf, wb->actual_buf);
} /* end if */
/* Check if size needed can be fulfilled with wrapped buffer */
if (need > wb->wrapped_size) {
/* Need to allocate new buffer */
if (NULL == (wb->actual_buf = H5FL_BLK_MALLOC(extra_buf, need)))
HGOTO_ERROR(H5E_ATTR, H5E_NOSPACE, NULL, "memory allocation failed");
/* Remember size of buffer allocated */
wb->alloc_size = need;
} /* end if */
else {
/* Don't have to allocate a new buffer, use the wrapped one */
wb->actual_buf = wb->wrapped_buf;
wb->alloc_size = 0;
} /* end else */
/* Set the return value */
ret_value = wb->actual_buf;
done:
/* Remember size of buffer used, if we were successful */
if (ret_value)
wb->actual_size = need;
FUNC_LEAVE_NOAPI(ret_value)
} /* end H5WB_actual() */
/*-------------------------------------------------------------------------
* Function: H5WB_actual_clear
*
* Purpose: Get the pointer to an "actual" buffer, of at least a certain
* size. Also, clear actual buffer to zeros.
*
* Return: Pointer to buffer pointer on success
* NULL on failure
*
*-------------------------------------------------------------------------
*/
void *
H5WB_actual_clear(H5WB_t *wb, size_t need)
{
void *ret_value; /* Return value */
FUNC_ENTER_NOAPI(NULL)
/*
* Check arguments.
*/
assert(wb);
assert(wb->wrapped_buf);
/* Get a pointer to an actual buffer */
if (NULL == (ret_value = H5WB_actual(wb, need)))
HGOTO_ERROR(H5E_ATTR, H5E_NOSPACE, NULL, "memory allocation failed");
/* Clear the buffer */
memset(ret_value, 0, need);
done:
FUNC_LEAVE_NOAPI(ret_value)
} /* end H5WB_actual_clear() */
/*-------------------------------------------------------------------------
* Function: H5WB_unwrap
*
* Purpose: "unwrap" a wrapped buffer, releasing all resources used
*
* Return: SUCCEED/FAIL
*
*-------------------------------------------------------------------------
*/
herr_t
H5WB_unwrap(H5WB_t *wb)
{
FUNC_ENTER_NOAPI_NOINIT_NOERR
/*
* Check arguments.
*/
assert(wb);
assert(wb->wrapped_buf);
/* Release any extra buffers allocated */
if (wb->actual_buf && wb->actual_buf != wb->wrapped_buf) {
/* Sanity check */
assert(wb->actual_size > wb->wrapped_size);
wb->actual_buf = H5FL_BLK_FREE(extra_buf, wb->actual_buf);
} /* end if */
/* Release the buffer wrapper info */
wb = H5FL_FREE(H5WB_t, wb);
FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5WB_unwrap() */
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