Category: Code

Correctly print uint64_t / size_t in C

GullCode

Have you even stumbled upon a strange warning when trying to print an uint64_t or a size_t ?
Do no take that warning lightly, as your code can break anytime if you’re not fixing it.

Warning example:

warning: format '%llu' expects argument of type 'long long unsigned int', but argument 4 has type 'uint64_t' [-Wformat]

To avoid the warning and crashes, you have to use a one of the PRIxxx macro which will choose the right way for your system to print the value, without crashes.
Example:

#include <inttypes.h>
uint64_t i;
printf("%"PRIu64"\n", i);

Macros for printf family can be found here.

New portapack mayhem app, Level app !

GullCode
Level app interface

The level app is as simple as possible and allow you to monitor available level meters in a single view.
There is a live graph of each RSSI values and power level.

Link to Documentation

Link to official Nightly build

or click to download compiled version at the time of the post (bin only)

#hackrf #portapack #mayhem #level-app

Edit: it’s the hundredth post of that blog, yay !

KrampusHack 2022 is opened !

GullCode

KrampusHack 2022 is opened and starting on December 13 to December 31 !

goal. You are secret santa – create a surprising gift for a selected participant.
On Tuesday 13 December 2022, you will be assigned one of the other participants and you have to make your game as a gift for them (Once the competition starts, you can read here for whom you have to make a gift).

Everyone should post a wishlist of features that they would like to see in the game. Note this is a wishlist and not a requirement list – you should tune the game to your giftee, taking the wishlist as well as the person itself into account, and create something that is a nice and thoughtful surprise to them. To make your wish list easily findable, simply post it on your own log.

Rules: https://tins.amarillion.org/krampu22/rules

Join in and have fun with us ! https://tins.amarillion.org/join/

#tins #gamejam #hack #krampus #krampushack

Warnings from the compiler / linker

GullCode

I was searching about a very specific warning that the gcc compiler started to sprout some few weeks ago:

That I extracted and translated from the original that was in French:

“/usr/bin/ld: warning: xxxxxxx.o: requires executable stack (because the .note.GNU-stack section is executable)”

And I stumbled upon that little gem page was one of the few to have a correct explanation:

https://www.redhat.com/en/blog/linkers-warnings-about-executable-stacks-and-segments

And also a few more here:
https://wiki.gentoo.org/wiki/Hardened/GNU_stack_quickstart

#gcc #compiler #linker #warning

Git remove commit from a pushed pull request

GullCode

If ever you have to remove a commit from a pushed pull request, here is a simple way to do it. Bonus: it’s not adding a commit for the removal.

First be sure to be on the good branch

git checkout target-pull-request-branch

Then have a watch at the PRs commit tab and note the commits hash you want to remove (one or more)

Replace X by that number in the following command, which will make and interactive rebase for the X last commits

git rebase -i HEAD~X

You are now going to have an interactive text view, in which all the aimed commits are preceded by the word ‘pick’

Using the view like a text editor, replace the ‘pick’ word by ‘drop’ on the lines containing the targeted commit’s hashes .

Exemple

Replaced pick with drop for commits 4aa3149 and 2031a79b:


Save and exit

In my case vim was the default text editor, so here you go escape colon w q

Push force the rebased repository

git push --force

This will remove the targeted commits and the only trace will be in the PR comments. The commit page will look like the rebased one, without the discarded commits nor a mention to them.

KAFKA

GullCode

KAFKA is in all mouths these days. So I share here, also as a reminder for me, a couple of #KAFKA ressources that looked helpful to me.

TLDR:

Do not use KAFKA for:

-“Little” Data flows (overkill)

-Streaming ETL (handling transformation is a hassle)

-Store and process large files (images, videos, proprietary files, etc.)

https://www.kai-waehner.de/blog/2020/08/07/apache-kafka-handling-large-messages-and-files-for-image-video-audio-processing/

https://www.upsolver.com/blog/apache-kafka-use-cases-when-to-use-not

https://kafka.apache.org/intro

https://docs.confluent.io/kafka-clients/librdkafka/current/overview.html

https://docs.confluent.io/platform/current/clients/librdkafka/html/md_INTRODUCTION.html

Why gettimeofday() is bad at timing things

GullCode

I was reading a changelog from a library I love (unrelated but here is the link: https://liballeg.org/ ) and I stumble upon that change:


“Use clock_gettime with CLOCK_MONOTONIC instead of gettimeofday (check-switch-26)”

Then I did a bit of research on the topic, and found a good explanation here:

https://blog.habets.se/2010/09/gettimeofday-should-never-be-used-to-measure-time.html

TLDR: if you use gettimeofday to time things then your program may be affected by time shift, because gettimeofday is not monotonic. if you do not care about the date and only about elapsed time, use clock_gettime.

HackRF Portapack Mayhem Firmware, Search/Freqman evolution branch

GullCode

On top of the existing ‘search and stay X seconds after a match’ the SearchApp have been updated with a ‘search and stay’ mode: stay while matching, leave after X seconds of inactivity, reset counters on activity during the wait. mode,
To use it just specify a negative value in the ‘wait’ field using the rotary encoder.

As some have some problems getting the bin back from discord, here you are:

portapack-h1_h2-mayhem.binDownload

The documentation is on the wiki, here:

https://github.com/GullCode/portapack-mayhem/wiki/Search

Github page:

https://github.com/GullCode/portapack-mayhem

CSS trick for rowspan and nth-child matching

GullCode

If ever you try to make a table with a single <td> matching more than one line using rowspan, your css that was using nth-child to customize each column is working badly. Only the first line of each rowspan is correctly recognized by the nth-child. All other lines are all shifted by one.

That’s because the css engine is not taking in accound the rowspan attribute.

Solution:

In my case it was to add all the <td> hidden by the rowspan like <td style=”display:none”> so they are here for the css engine to count properly, but not displayed at all.

grep: retain colors when piping

GullCode

By default grep -color is not producing color symbols if it detects that the output is not a terminal.

grep -color=auto is doing the same, that is not producing color symbols if it detects that the output is not a terminal.

The solution is to use “grep -color=always“ in the place that need it.

Do not put it in an alias of grep as it would break some code somewhere else. Color symbols are strings like “ESC[35m” and they will be inserted in the text.

Portapack firmware with Search App and updated Freqman files (based on latest next )

GullCode
  • I’ve build an up to date firmware with the last updates from next and the last version from search app and freqman enhancements.
  • The Search app is in the ‘receive’ menu
  • The documentation is here : https://github.com/GullCode/portapack-mayhem/wiki/Search
  • -Freqman now do understand freq files with that format:
    f=468000000 f=468000000,d=Single Freq f=468000000,m=AM,d=Single Freq AM f=468000000,m=NFM,d=Single Freq NFM f=468000000,m=WFM,d=Single Freq WFM f=468000000,m=AM,b=DSB,d=Single Freq AM DSB f=468000000,m=AM,b=USB,d=Single Freq AM USB f=468000000,m=AM,b=LSB,d=Single Freq AM LSB a=87000000,b=110000000 a=87000000,b=110000000,m=AM,s=100KHz,d=AM radio search a=87000000,b=110000000,m=AM,b=DSB,s=250KHz,d=AM radio search LSB a=87000000,b=110000000,m=WFM,b=16k,s=50KHz,d=WFM radio search s=50KHz r=430150000,t=430550000 r=430150000,t=430550000,d=HAM radio r=430150000,t=430550000,m=AM,b=DSB,d=HAM radio
  • The freqman GUI have note been improved and may show partial results on new formatted lines
  • Description of the fields:
    f=freq for one frequency or a=start_frequency,b=end_frequency for a range
    m=modulation
    b=bandwidth
    s=step
    d=description
  • All fields except ‘f=freq’ or ‘a=freqA,b=freqB’ are mandatory. If nothing specified actual value is used.
  • As a reminder :
    -Most of the time if the Search app is not working as you expected it’s coming from a SDCARD problem.
    -You need a SDCARD for the Search app to save settings between runs and between settings menu / main gui, and you need a SEARCH folder at the root of it.
    -Don’t forget to check that by default the ‘input: load’ fields in ‘search app -> params -> more ‘ are all checked.
    -You HAVE to click save in ordre to save the settings.
portapack-h1_h2-mayhem.binDownload