[SOLVED] How to interpret relational operators in a macro?

jani1 · 12-19-2019, 02:06 PM

Please provide an example that uses following macros.
What part is macro, and what part is replacement token?

filename: linux/arch/include/asm/cache.h

Code:

/* Largest line length for either L1 or L2 is 128 bytes */
 50 #define SMP_CACHE_BYTES>> 128
 51 #define cache_line_size()>SMP_CACHE_BYTES
 52 #define ARCH_DMA_MINALIGN>SMP_CACHE_BYTES

NevemTeve · 12-19-2019, 02:43 PM

Maybe you were using 'mcedit' to see the content of this file?
'mcedit' displays Tabulator character as <------>

jani1 · 12-19-2019, 03:19 PM

I'm using vim editor to see contents of this file.

jani1 · 12-19-2019, 03:25 PM

I'm seeing these characters > and >> in other lines as well.

struct usb_device {
105 > int>devnum;>> > /* Device number on USB bus */
106 > int>speed;> > > /* full/low/high */
107 > char> mf[32];>> > /* manufacturer */
108 > char> pro

Why does vim display these characters?

Geist · 12-19-2019, 04:37 PM

Quote:

Originally Posted by jani1

I'm seeing these characters > and >> in other lines as well.

struct usb_device {
105 > int>devnum;>> > /* Device number on USB bus */
106 > int>speed;> > > /* full/low/high */
107 > char> mf[32];>> > /* manufacturer */
108 > char> pro

Why does vim display these characters?

It's the

Code:

set list

options,

Code:

set nolist

to turn it off and

Code:

set listchars=tab:>-,trail:-

to change how they look.

Anyway, this looks like homework, so, work on it :P
If you were to add macros into the C language, how would you do it? Maybe that will help.
Think about the syntax of the C language.

NevemTeve · 12-19-2019, 08:20 PM

In vim-8.0, :set nolist worked for me.

jani1 · 12-20-2019, 07:40 AM

>> this looks like homework
I'm not a student. I'm trying to learn USB host implementation in u-boot so I can write USB Host code to detect unusual device that is USB Device Class "Vendor Defined"

:set nolist also worked for me. Thank you!

pan64 · 12-20-2019, 11:07 AM

Quote:

Originally Posted by jani1

I'm trying to learn USB host implementation in u-boot so I can write USB Host code to detect unusual device that is USB Device Class "Vendor Defined"

How is this related to the original post? Do you have a test code or an example to work with?

jani1 · 12-20-2019, 11:15 AM

>> How is this related to the original post?
It's not related to the original post. I was just trying to give reason as to why my original question isn't homework.

Geist · 12-20-2019, 03:39 PM

Quote:

Originally Posted by jani1

>> How is this related to the original post?
It's not related to the original post. I was just trying to give reason as to why my original question isn't homework.

Haha, fair, it was the wording, though.

Quote:

Please provide an example that uses following macros.
What part is macro, and what part is replacement token?

It's something you might find in a textbook.
Anyway, the macro name comes first, the definition comes afterward.

Code:

#define macro_name return 0

int return_null()
{
    macro_name;
}

Note that the macro_name does not have a semicolon at the end, that's because the word "macro_name" gets expanded into the text you have given, think of it like a copy paste.
There's a lot more to it, of course, but that's basically how a macro is set up, the name you define for it, and then the text you want it to represent.

This link has a more in depth overview, including some pitfalls to look out for and how to deal with them.

jani1 · 12-22-2019, 05:39 PM

>> it was the wording, though.
Yes, okay.

Thank you for answer and link.