about sizeof struct problem

ling ling

Hi everyone.

I am using dm8168 on DVRRDK_04.00.00.03.

In DSP side,I define a strcut like

typedef struct tagHEADER {
unsigned short    bfType;
unsigned long   bfSize;
unsigned short    bfReserved1;
unsigned short    bfReserved2;
unsigned long   bfOffBits;
} XXXHEADER;

and I am expecting sizeof(XXXHEADER)=14

but actually it is 16.

In the ARM side I can use the #pragma pack(1) to get the result that I wanted,but the DSP side no #pragma pack(1) to use,and I read the cgt6x_7_3_5\doc\SPRU187T.pdf,the cl6x compiler provide the

#pragma STRUCT_ALIGN(symbol，constant);

#pragma DATA_ALIGN( symbol，constant）

and I set the constant to 1,It does not work.

why???

over 11 years ago

0 Norman Wong over 11 years ago

Guru 26430 points

Are you using COFF or EABI? In COFF, long is 40 bits or 5 bytes. In EABI, long is 32 bits. Try using "int" instead of "long".

You can try applying the packed attribute. You must enable GCC extensions in the compiler.

typedef struct tagHEADER {
  ...
} __attribute__ ((packed)) XXXHEADER;

0 ling ling over 11 years ago in reply to Norman Wong

Intellectual 350 points

It works.

thank you Norman.

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