Re: [Dev-C++] Re: malloc , extra bytes ! Got even more urgent !

[veenurs <ve...@ma...>]

Hi PW ,
 Well , I guessed  it had something to do with the AT Least qualifier 
.But , I just can't help bothoring abt . the extra bytes !
 It's lioke this- the memory created is used to store bytes of formatted 
data , which are then to be used by another part of application . So , 
the extra bytes are screwing up the formatting and making 6the data 
useless !!
The data itself is comming from   decryption  routines , so I cannot be 
sure of the exact size before decryption ( therefore , I NEED the 
malloc- realloc thing , would hate to use arrays .)

MoreOvere , There is no such problem In VC++ ( I have a learner ed.), or 
LCC .

Thanks , any other solution ?

-Rahul.

Per Westermark wrote:

>Stop bothering about the size of the returned memory block.
>
>The allocation functions are only required to return AT LEAST the required
>amount of memory, or a NULL pointer.
>
>Internally, they normally add 8-16 byte of internal header for
>book-keeping on the heap, i.e. to allow the heap manager to walk free and
>used memory block.
>
>Besides, most heap managers performs one of the following:
>- rounds each block up to the nearest 8 or 16 byte increment.
>- allocates the nearest larger 2^n size.
>- uses the buddy system and allocates the nearest larger block size.
>
>As a result - for allocation of very small objects, it might often
>be better to allocate a bunch of objects at a time, and keep pool of
>evailable objects in a list.
>
>In the example below, the calloc call MUST use sizeof(BYTE). The
>statement calloc(1000,BYTE) doesn't make sense.
>
>/Per W
>
>On Mon, 24 Feb 2003, Danny Roelofs wrote:
>
>  
>
>>Hi,
>>
>>Well i dont realy know what youre doing with it.. and i never used calloc but it seems your allocating memory for 1000 bytes
>>and a additional 8 bytes..  sizeof(byte) reserves 8 bytes in my opinion. is it perhaps that you have to do this:
>>
>>calloc(1000,BYTE) instead of calloc(1000,sizeof(BYTE))
>>
>>Well i actualy dont know.. i am just programming in C for just a month or so..
>>
>>
>>  ----- Original Message -----
>>  From: veenurs
>>  To: dev...@li... ; ra...@ww...
>>  Sent: Monday, February 24, 2003 1:16 AM
>>  Subject: [Dev-C++] Re: malloc , extra bytes ! Somewhat urgent !
>>
>>
>>
>>
>>  Hi !
>>  It seems too simple .But what is it !?
>>  if( (buffer = ( PBYTE )calloc( 1000 ,sizeof(BYTE) )) == NULL ){
>>         ------
>>        -------
>>  }
>>    size = _msize( buffer );
>>
>>  The size I get it is not 1000 , but 1008  !Same for malloc. Any subsequent call to realloc  does not add  the 8 bytes,though  .
>>
>>  [ Dev Cpp Version 4.9.7.0 ]
>>  What's happening ?
>>  BTW - "Generate debugging info" is OFF .
>>  Thanks in advance .
>>
>>  -Rahul.
>>
>>
>>
>>    
>>
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