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Re: [avr-gcc-list] Include ASM in C

From: Harald Kipp
Subject: Re: [avr-gcc-list] Include ASM in C
Date: Fri, 08 Jun 2001 20:40:40 +0100 (MEZ)

Hi Elmar,

>but when I do the same but replacing the address of the port by its label
>asm volatile("sbi PORTB,0x07;");
>I get a compilation error: "Error: constant value required"
>This happens even if I define a constant like:
>#define MYPORTB 0x15
>asm volatile("sbi MYPORTB,0x07;");

You have to think in C, not ASM. The assembler
instructions are string constants and the C
preprocessor won't change them. So the string
"sbi MYPORTB,0x07;" is passed unmodified to
the assembler. But the assembler won't see
you C defines. Hope, that this wasn't explained
too complicated.

More hint could be found in my little Inline
Assembler Cookbook at


The name of the file is GCCAVRInlAsmCB.pdf.

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