Re: [Uisp-dev] [patch] Alignment on ARM

[Raphael Assenat]

Wojtek Kaniewski wrote:
> Raphael Assenat napisał(a):
>
> > The supplemental bytes are due to the sizeof(struct SPrgParams) being 
> > equal to 24 on arm due to alignment/padding of the struct by the 
> > compiler. On an x86, it is 22 bytes.
> >
> > I tried using #pragma pack(1), -fpack-structs, but the size of the 
> > struct stayed at 24. Finally, I decided to copy manually all the members
> > of the structure into the buffer and I hardcoded the length to 22 (see 
> > diff below). That worked.
>
>
> struct SPrgParams {
>   // ...
> } __attribute__ ((packed));
>
> should do the thing.
I tried your suggestion and it worked perfectly. And it's much cleaner.

Regards,
Raphael Assenat

diff -Nru uisp/src/Stk500.h uisp-edited2/src/Stk500.h
--- uisp/src/Stk500.h   2005-04-19 11:19:54.859217144 -0400
+++ uisp-edited2/src/Stk500.h   2005-04-20 14:32:06.220387296 -0400
@@ -66,7 +66,7 @@
   const TByte eepromsize[2];    // Size of eeprom in bytes.
   const TByte flashsize[4];     // Size of FLASH in bytes.
   const TByte sync;             // Always 0x20 (Sync_CRC_EOP)
-};
+} __attribute__ ((packed));

 /* Set the Extened Device Programming parameters. In the future, this may
    require more than 3 arguments. */