Lpc2000

You would need:

typedef struct
{
  uint8_t bsjmpBoot[3];
  char 	bsOEMName[8];
  uint16_t bsBytesPerSec;
  ...
}  __attribute__((packed)) BootSector; 

Given...

BootSector bs;

...then...

BS.bsBytesPerSec = 1

...generates...

BS.bsBytesPerSec = 1;
   	E59F200C   ldr r2, [pc, #12]
   	E3843001   orr r3, r4, #0x00000001
   	E5C2300B   strb r3, [r2, #11]
   	E5C2400C   strb r4, [r2, #12]

So, bsBytesPerSec is accessed as bytes at offsets 11 and 12, which is
just what you wanted, isn't it?

--
Paul Curtis, Rowley Associates Ltd  http://www.rowley.co.uk
CrossWorks for MSP430, ARM, AVR and now MAXQ processors

> -----Original Message-----
> From: nourson54 [mailto:nourson54@...] 
> Sent: 20 September 2005 16:31
> To: lpc2000@yahoogroups.com
> Subject: [lpc2000] Re: Struct/Union alignement problem with Crossworks
> 
> here's a part of code :
> typedef struct
> {
>   uint8_t bsjmpBoot[3];
>   char 	bsOEMName[8];
>   uint16_t bsBytesPerSec;
>   ...
> }BootSector;
> 
> and a buffer FAT16_buffer[512] where I put data frome SD card in.
> 
> for example , if I declare a Bootsector struct at same 
> address of FAT16_Buffer, and read the first sector of my 
> SDcard, I coul read directly the field of my struct.
> 
> bsjmpBoot is 3 bytes and is OK
> BsOEMName is 8 bytes and OK
> bsByteBytesPerSec is 2 bytes is not OK because bsOEMBoot+bsOEMName =
> 11 bytes : 1 bytes is 'filled' between bsOEMName and bsBytesPerSec. 
> So data becomes buggy.
> 
> 
> with the #pramga pack (x) , Can I 'byte align' each field of 
> my struct ?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --- In lpc2000@yahoogroups.com, "Angel Sanchez" <angelsp@a...> wrote:
> > In a similar situation I use:
> > 
> > #pragma pack (2)
> > 
> > ...
> > Structures, etc
> > 
> > #pragma pack ()
> > 
> > and this work (align at word boundaries)
> > 
> > Regards
> > Angel Sanchez
> > 
> > 
> > --- In lpc2000@yahoogroups.com, "nourson54" <nourson54@y...> wrote:
> > > Hello,
> > > 
> > > I'm trying a fat16 library that use an union for storing the 
> > > bootsector data, and it seems the compiler doesn't handle 
> correctly 
> > > the width of types in memory.
> > > So I searched some help on crossworks (gcc) compiler and 
> found that
> > I
> > > have to use this attribute with my concerned unions :
> > >  __attribute__ ((__packed__))
> > > 
> > > But if the compiler doesn't shout at me when compiling , 
> it seems it 
> > > has no effect : my union is badly aligned.
> > > 
> > > Have any idea ?
> 
> 
> 
> 
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