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>Fixed Size Allocation Pools</TITLE
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><H1
><A
NAME="FIXED-POOLS"
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>Fixed Size Allocation Pools</H1
><DIV
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><A
NAME="AEN15054"
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><H2
>Name</H2
>cyg_mempool_fix_create, cyg_mempool_fix_delete, cyg_mempool_fix_alloc, cyg_mempool_fix_timed_alloc, cyg_mempool_fix_try_alloc, cyg_mempool_fix_free, cyg_mempool_fix_waiting, cyg_mempool_fix_get_info -- Fixed Size Allocation Pools</DIV
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>Synopsis</H2
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><PRE
CLASS="FUNCSYNOPSISINFO"
>#include <cyg/kernel/kapi.h>
</PRE
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><P
><CODE
><CODE
CLASS="FUNCDEF"
>void cyg_mempool_fix_create</CODE
>(void* base, cyg_uint32 size, cyg_uint32 blocksize, cyg_handle_t* fixpool, cyg_mempool_fix* fix);</CODE
></P
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void cyg_mempool_fix_delete</CODE
>(cyg_handle_t fixpool);</CODE
></P
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void* cyg_mempool_fix_alloc</CODE
>(cyg_handle_t fixpool);</CODE
></P
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void* cyg_mempool_fix_timed_alloc</CODE
>(cyg_handle_t fixpool, cyg_tick_count_t abstime);</CODE
></P
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void* cyg_mempool_fix_try_alloc</CODE
>(cyg_handle_t fixpool);</CODE
></P
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void cyg_mempool_fix_free</CODE
>(cyg_handle_t fixpool, void* p);</CODE
></P
><P
><CODE
><CODE
CLASS="FUNCDEF"
>cyg_bool_t cyg_mempool_fix_waiting</CODE
>(cyg_handle_t fixpool);</CODE
></P
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void cyg_mempool_fix_get_info</CODE
>(cyg_handle_t fixpool, cyg_mempool_info* info);</CODE
></P
><P
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><A
NAME="MEMALLOC-FIXED-DESCRIPTION"
></A
><H2
>Description</H2
><P
> The fixed size memory pool functions are used for allocating
blocks of the same size. The allocation and free functions are
more efficient than the variable size pools, but are naturally
limited to being only able to allocate blocks of a sized
size. Before memory can be allocated the pool must first be
created by calling
<CODE
CLASS="FUNCTION"
>cyg_mempool_fix_create()</CODE
>.
The parameter <CODE
CLASS="PARAMETER"
>base</CODE
> is a point to the
bottom of the memory area to be used by the pool and
<CODE
CLASS="PARAMETER"
>size</CODE
> is the size of the memory area in
bytes. <CODE
CLASS="PARAMETER"
>blocksize</CODE
> indicates the size of
each allocation in bytes. The function also takes a pointer to a
<CODE
CLASS="STRUCTNAME"
>cyg_mempool_fix</CODE
> data structure which is
typically statically allocated, and may be part of a larger data
structure. It should be noted that some memory is take from the
pool for book keeping purposes. If a memory pool is no longer
required and there are not threads waiting to allocate memory
from it, it can be destroyed with
<CODE
CLASS="FUNCTION"
>cyg_mempool_fix_delete()</CODE
>.
</P
><P
> Memory can be allocated from the pool using a number of
functions. They all take the
paramter<CODE
CLASS="PARAMETER"
>fixpool</CODE
>which indicates which pool
should be used. <CODE
CLASS="FUNCTION"
>cyg_mempool_fix_alloc()</CODE
>
will block until the memory becomes
available. <CODE
CLASS="FUNCTION"
>cyg_mempool_tryalloc()</CODE
>will try
not block if no memory is available and will return
<TT
CLASS="LITERAL"
>NULL</TT
>. Otherwise a pointer to the allocated
memory will be returned.
<CODE
CLASS="FUNCTION"
>cyg_mempool_fix_timed_alloc()</CODE
> will block if
memory is not available and wait for memory to become available
until the time<CODE
CLASS="PARAMETER"
>abstime</CODE
> is reached. It will
then return <TT
CLASS="LITERAL"
>NULL</TT
>. </P
><P
> Allocated memory can be freed using the function <CODE
CLASS="FUNCTION"
>cyg_mempool_fix_free()</CODE
>.
</P
><P
> Lastly it is possible to query information about the pool using
the function
<CODE
CLASS="FUNCTION"
>cyg_mempool_fix_get_info()</CODE
>. This takes a
pointer to the structure <CODE
CLASS="STRUCTNAME"
>cyg_mempool_info</CODE
> which is:
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><PRE
CLASS="PROGRAMLISTING"
>typedef struct {
cyg_int32 totalmem;
cyg_int32 freemem;
void *base;
cyg_int32 size;
cyg_int32 blocksize;
cyg_int32 maxfree;
} cyg_mempool_info;
</PRE
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