NASM - The Netwide Assembler

NASM Forum => Programming with NASM => Topic started by: communism on August 15, 2015, 06:06:55 PM

Title: error: division operator may only be applied to scalar values
Post by: communism on August 15, 2015, 06:06:55 PM

I have two lines of code in my program that don't get along with NASM very well;

Code: [Select]

lea eax, [ebp-ecx/2]
lea ebx, [argv-ecx/2]
and I'm getting;

Code: [Select]

program.asm:56: error: division operator may only be applied to scalar values
program.asm:57: error: division operator may only be applied to scalar values
when trying to compile. I thought that regular arithmetic would be kosher... apparently not.

Any suggestions?

Title: Re: error: division operator may only be applied to scalar values
Post by: Frank Kotler on August 15, 2015, 09:30:41 PM

Use instructions that exist.

An effective address can consist of an (optional) displacement plus an (optional) base register plus an (optional) index register multiplied by a scale of 1, 2, 4, or 8. A scale factor of 1/2 is not available. (if it were, would it address a half byte?) The minus sign isn't going to work, either.

Usually when Nasm complains about not having a "scalar value", it means you've tried to do arithmetic on a label - a "relocatable value". The difference between two labels is a "scalar value" and you can do it, but that won't help you here.

Best,
Frank