Lpc2000

At 04:40 PM 4/29/06 +0000, rtstofer wrote:
>I had the same problem when I ported the FAT code from AVRLib to my
>LPC2106 project.  I went with the non-portable approach:
>
>struct bootsector710 {
>     unsigned int     bsJump:24;
>     unsigned char    bsOEMName[8];
>     unsigned char    bsBPB[53];
>     unsigned char    bsExt[26];
>     unsigned char    bsBootCode[418];
>     unsigned char    bsBootSectSig2;
>     unsigned char    bsBootSectSig3;
>     unsigned char    bsBootSectSig0;
>     unsigned char    bsBootSectSig1;
>#define BOOTSIG0        0x55
>#define BOOTSIG1        0xaa
>#define BOOTSIG2        0
>#define BOOTSIG3        0
>} __attribute__ ((packed));  <=== non-portable
>
>I didn't have the ability to change the structure - that's the way the
>data is set out on the disk.
>
>These structs are defined and accessed in a single source file.  I can
>live with it.

Which leads to a third semi-portable possibility

struct bootsectorport {
     unsigned int     bsJump:24;
     unsigned char    bsOEMName[8];
     unsigned char    bsBPB[53];
     unsigned char    bsExt[26];
     unsigned char    bsBootCode[418];
     unsigned char    bsBootSectSig2;
     unsigned char    bsBootSectSig3;
     unsigned char    bsBootSectSig0;
     unsigned char    bsBootSectSig1;
};


struct bootsector710 a;
struct bootsectorport b;

And to convert from a to b

b.bsJump = a.bsJump;
memcpy( b.bsOEMName, a.bsOEMName, sizeof(b.bsOEMName));

etc..

A little cleaner looking than massaging byte by byte.  You have to change 
how you define the packed structure when porting but that can be confined 
to a small area.  Not truly portable but it covers a lot of cases.

Robert

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