Lpc2000

Hi all,

i am confused with the words and byte relation in EP_RAM size. they are
saying EP_RAM is word aligned. and FIFO maximum size is in bytes, so, we
will have to align the allocation.

however, they ary making it as EP_RAMsize=(Maxpacketsize + 3) / 4 + 1, in
this are they taking 1 word=4 bytes? but as i know 1 word, in most cases we
define as 2 bytes and DWORD 4 bytes.

Thanks for going through the problem.

if anyone has any idea please help me.

Regards
Manisha.


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--- In lpc2000@yahoogroups.com, "Manisha" <manisha@...> wrote:
>
> Hi all,
> 
> i am confused with the words and byte relation in EP_RAM size. they are
> saying EP_RAM is word aligned. and FIFO maximum size is in bytes, so, we
> will have to align the allocation.
> 
> however, they ary making it as EP_RAMsize=(Maxpacketsize + 3) / 4 +
1, in
> this are they taking 1 word=4 bytes? but as i know 1 word, in most
cases we
> define as 2 bytes and DWORD 4 bytes.
> 
> Thanks for going through the problem.
> 
> if anyone has any idea please help me.
> 
> Regards
> Manisha.
> 
> 

DWORD is kind of an Intel thing.  I don't see it described in the GNU
manuals (other than under FRV) so if it applies to ARM at all, it is
compiler vendor specific.

The ARM word is 32 bits - it is not 2-16 bit entities treated as a 32
bit entity as it was in the early Intel chips.  Two signed or unsigned
16 bit integers can be packed in a 32 bit word as can four signed or
unsigned bytes.

Richard

Thanks a ton Richards.

actually the Atmel board with ARM processor supports the transaction in
bytes format. as i suppose no word stuff is involved there. No alignment
needed. so, got confused with philips spec.

regards
Manisha

-----Original Message-----
From: lpc2000@yahoogroups.com [mailto:lpc2000@yahoogroups.com]On Behalf
Of rtstofer
Sent: Tuesday, March 07, 2006 12:51 PM
To: lpc2000@yahoogroups.com
Subject: [lpc2000] Re: EP_RAMsize and Words and bytes


--- In lpc2000@yahoogroups.com, "Manisha" <manisha@...> wrote:
>
> Hi all,
>
> i am confused with the words and byte relation in EP_RAM size. they are
> saying EP_RAM is word aligned. and FIFO maximum size is in bytes, so, we
> will have to align the allocation.
>
> however, they ary making it as EP_RAMsize=(Maxpacketsize + 3) / 4 +
1, in
> this are they taking 1 word=4 bytes? but as i know 1 word, in most
cases we
> define as 2 bytes and DWORD 4 bytes.
>
> Thanks for going through the problem.
>
> if anyone has any idea please help me.
>
> Regards
> Manisha.
>
>

DWORD is kind of an Intel thing.  I don't see it described in the GNU
manuals (other than under FRV) so if it applies to ARM at all, it is
compiler vendor specific.

The ARM word is 32 bits - it is not 2-16 bit entities treated as a 32
bit entity as it was in the early Intel chips.  Two signed or unsigned
16 bit integers can be packed in a 32 bit word as can four signed or
unsigned bytes.

Richard








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