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Re: [avr-gcc-list] memset does not show up in AVR Studio V4

From: Joerg Wunsch
Subject: Re: [avr-gcc-list] memset does not show up in AVR Studio V4
Date: Fri, 3 Jan 2003 10:59:00 +0100 (MET)

"Mike Bechtold" <address@hidden> wrote:

> I using GCC v3.2 objtool v0.5b.  the code for memset does not show
> up in avr Studio v.4.

Disclaimer: i don't have Windows, thus don't know much about

My guess is that this is due to the fact that gcc, when using any
level of optimization > 0, and when not using -ffreestanding,
generally inlines memset() into a few assembler instructions.  Of
course, from a souce-code point of view, it then doesn't descend into
a function you could single-step through, since it's just a single
line of C source (containing the "call" to memset()) that expands into
some assembler statements.

Single-stepping by CPU instruction should work.

For a quick test, here's what gcc expands for a call to
memset(functionarg#1, 0, 23); :

        ldi r18,lo8(23)
        movw r30,r24
        st Z+,__zero_reg__
        dec r18
        brne .-6

J"org Wunsch                                           Unix support engineer
address@hidden        http://www.interface-systems.de/~j/
avr-gcc-list at http://avr1.org

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