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give C struct to assembler...

Note: This was originally posted on 24th November 2011 at http://forums.arm.com

how can I send the offset of a C struct to en assembly code ? For example

In my C code I have

typedef struct
{
unsigned int a;
unsigned int b;
} CMyStruct;
I send to an ASM function a pointer of a CMyStruct structure Let suppose that my pointer is into R0

To access to a and b attribute I need to do that.

ldr      r1, [r0, #0] // read a
ldr      r2, [r0, #4] // read b
Is there anyway to not specify #0 and #4 as contant value ? Something like

ldr      r1, [r0, CMyStruct.a] // read a
ldr      r2, [r0, CMyStruct.b] // read b
Thank's Etienne

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Peter Harris over 12 years ago

Note: This was originally posted on 25th November 2011 at http://forums.arm.com

I'm not sure you can in GCC assembler - I've never seen it attempted directly.

The obvious workaround is calculate the necessary offsets in C and pass then in to the assembler function as parameters.
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Peter Harris over 12 years ago

Note: This was originally posted on 25th November 2011 at http://forums.arm.com

I'm not sure you can in GCC assembler - I've never seen it attempted directly.

The obvious workaround is calculate the necessary offsets in C and pass then in to the assembler function as parameters.
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