Is there any tutorial showing how to develop a C or C++ on Onion?

Or could you please tell me the steps for a hello world program?

I don't even know if I should do cross-compilation, or if I can install the compiler on the onion. If it is cross-compilation, I would ideally prefer to do it from Windows rather than Linux.

Thanks in advance!

btw, I have read the "Cross Compile" (https://wiki.onion.io/Tutorials/Cross-Compile), but it looks like it is rather devoted to compile the Onion Linux kernel, so I guess it is not what I need.

1. The Omega does not have sufficient memory resources to run a C/C++ build tool chain
2. Since you are on Windows (as I am), your best bet is to set up a VM (VirtualBox or Vmware) running a standard Linux distribution - I use Kubuntu 14.04 and run cross compilation from there. It is possible to gain direct access to the Omega from the Linux VM so long as the VM networking is set up correctly.
3. The following two posts may be of assistance to you - they cover what I am successfully doing for cross compilation of C/C++ code for the Omega:
   • https://community.onion.io/topic/9/how-to-install-gcc/20
   • https://community.onion.io/topic/125/using-netbeans-to-compile-c-c-code-for-omega

Hop these help

• install Kubuntu 14.04 64 bits on a VirtualBox VM

• follow KitBishop guidelines (great stuff initially here : https://community.onion.io/topic/9/how-to-install-gcc/22

• Download the tool chain from https://s3-us-west-2.amazonaws.com/onion-cdn/community/openwrt/OpenWrt-Toolchain-ar71xx-generic_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-x86_64.tar.bz2

• Unpack it to some suitable directory (referred to below as <tc_dir>)

• Set up environment variables as follows (I put this in my ~/.profile file so it was always there):

PATH=<tc_dir>/OpenWrt-Toolchain-ar71xx-generic_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-x86_64/toolchain-mips_34kc_gcc-4.8-linaro_uClibc-0.9.33.2/bin:$PATH

STAGING_DIR=<tc_dir>/OpenWrt-Toolchain-ar71xx-generic_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-x86_64/toolchain-mips_34kc_gcc-4.8-linaro_uClibc-0.9.33.2

export STAGING_DIR

• Create your c program - e.g. test-prog.c

• Compile the program using (e.g.): mips-openwrt-linux-uclibc-gcc test-prog.c -o test-prog

• Transfer the output file (test-prog) to your Omega using you favourite tools.

• On the Omega in the directory you placed the file, run it by: ./test-prog - and there you are

The program expects one argument being the microseconds to wait between 2 half-steps. In my case, below 600 it's too fast for the engine to follow, but any value higher is fine.

Thanks again KitBishop for this nice GPIO API!

Cheers

#include <cstdlib>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include "GPIOPin.h"
#include "GPIOAccess.h"

int main(int argc, char** argv) {
int d = atoi(argv[1]);
printf("delay=%d\n", d);

GPIOPin* pins[4];
pins[0] = new GPIOPin(0);
pins[1] = new GPIOPin(1);
pins[2] = new GPIOPin(6);
pins[3] = new GPIOPin(7);
for (int i = 0; i < 4; i++) {
pins[i]->setDirection(GPIO_OUTPUT);
}
int i = 0, j = 3;
for (;;) {
pins[i]->set(1);
usleep(d);
pins[j]->set(0);
usleep(d);
j = i++;
i = i % 4;
}
return 0;
}

In my docker project you can find a long conversation between another apprentice in compiling for Omega2 and me, and in the OP a little introduction to How to compile C code (right before the Edit 1)

If you have a toolchain already set, you don't need Docker. Everything said in the post that must be executed inside the docker container is what you must do with your own toolchain, if it is the right one, the MIPSel 24kc.

@anglo-marc the onion tutorial is for Omega 1, not Omega2. Did you use the MIPSel (little-endian) compiler?

In my docker project you can find a long conversation between another apprentice in compiling for Omega2 and me, and in the OP a little introduction to How to compile C code (right before the Edit 1)

If you have a toolchain already set, you don't need Docker. Everything said in the post that must be executed inside the docker container is what you must do with your own toolchain, if it is the right one, the MIPSel 24kc.

thanks dear for replaying
actually im beginner in this field
and unfortunately there are no Clear tutorials to explain that !
the Onion did not release enough resources !

The biggest problem was getting the environment variables to remain valid over a reboot! Thanks very much for the pointers.

I have managed to get as far as

CLEAN SUCCESSFUL (total time: 60ms)
cd '/home/ianm/ogps'
/usr/bin/make -f Makefile
[ 33%] Building C object CMakeFiles/ugps.dir/main.c.o
[ 66%] Building C object CMakeFiles/ugps.dir/nmea.c.o
[100%] Linking C executable ugps
/home/ianm/toolchain/toolchain-mipsel_24kc_gcc-5.4.0_musl-1.1.15/bin/../lib/gcc/mipsel-openwrt-linux-musl/5.4.0/../../../../mipsel-openwrt-linux-musl/bin/ld: cannot find -lubox
/home/ianm/toolchain/toolchain-mipsel_24kc_gcc-5.4.0_musl-1.1.15/bin/../lib/gcc/mipsel-openwrt-linux-musl/5.4.0/../../../../mipsel-openwrt-linux-musl/bin/ld: cannot find -lubus
collect2: error: ld returned 1 exit status
CMakeFiles/ugps.dir/build.make:120: recipe for target 'ugps' failed
make[2]: *** [ugps] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/ugps.dir/all' failed
make[1]: *** [CMakeFiles/ugps.dir/all] Error 2
Makefile:127: recipe for target 'all' failed
make: *** [all] Error 2

has anyone else tried this yet? I think it is upset about libraries but I am not 100% on this as the whole linux things is a bit new to me at present.

so >> why this ?

check link below !
https://lede-project.org/docs/guide-developer/install-buildsystem
my os . Ubuntu 14
not supported !

hope some serious support from official onion .

hope some serious support from official onion .

There have already been a lot of threads here explaining how to build C programs, both via building a LEDE cross toolchain as part of a "close enough" LEDE build, or by a ready-to-go docker virtual machine image that has been offered. For someone in a position to really do native development, these work fine, and are the standard approach for an Embedded Linux system of this category.

It might be important to recognize that C development isn't really a primary goal of the product, compared to scripting languages and web widgets. Rather than chasing every varied user request (and especially those such as this that are already well covered by the community), the onion team's time would be far better spent catching up on their overdue obligations for corresponding source releases - the thing that only they can do.

In comparison to something that some might call a success, like the Raspberry Pi, the key takeway has to be that the system vendor there is only providing the Hardware and the directly required GPL sources - most of the resources people think of in the pi ecosystem, including Raspbian itself, do not come from the hardware vendor. It's a rich ecosystem precisely because they have enabled their community, and not restricted it to the glacial pace of doing everything themselves.

@anglo-marc said in Programming in C/C++?:

hope some serious support from official onion .

There have already been a lot of threads here explaining how to build C programs, both via building a LEDE cross toolchain as part of a "close enough" LEDE build, or by a ready-to-go docker virtual machine image that has been offered. For someone in a position to really do native development, these work fine, and are the standard approach for an Embedded Linux system of this category.

It might be important to recognize that C development isn't really a primary goal of the product, compared to scripting languages and web widgets. Rather than chasing every varied user request (and especially those such as this that are already well covered by the community), the onion team's time would be far better spent catching up on their overdue obligations for corresponding source releases - the thing that only they can do.

In comparison to something that some might call a success, like the Raspberry Pi, the key takeway has to be that the system vendor there is only providing the Hardware and the directly required GPL sources - most of the resources people think of in the pi ecosystem, including Raspbian itself, do not come from the hardware vendor. It's a rich ecosystem precisely because they have enabled their community, and not restricted it to the glacial pace of doing everything themselves.

thanks for interesting
but .. realy !!
the steps not clear !

the steps not clear !

The topic is an advanced one, but the necessary information has been provided.

You'll need to spend more time reading and learning. In particular, handling any uniqueness of your particular development machine's Linux installation is uniquely your task, not anyone else's.

The intent was that those wanting a simple path would be using pre-built capabilities and scripting languages, not C.

gccmips: warning: environment variable 'STAGING_DIR' not defined
cc1: warning: command line option '-std=gnu++11' is valid for C++/ObjC++ but not for C [enabled by default]
In file included from ../libnewgpio/hdr/GPIOPin.h:5:0,
from sm_rotate.c:5:
../libnewgpio/hdr/GPIOTypes.h:37:24: error: expected '=', ',', ';', 'asm' or 'attribute' before '{' token
GPIO_Irq_Handler_Object{
^
../libnewgpio/hdr/GPIOTypes.h:44:28: error: expected '=', ',', ';', 'asm' or 'attribute' before '{' token
GPIO_PulseIn_Handler_Object{
^
In file included from sm_rotate.c:5:0:
../libnewgpio/hdr/GPIOPin.h:7:1: error: unknown type name 'class'
class GPIOPin {
^
../libnewgpio/hdr/GPIOPin.h:7:15: error: expected '=', ',', ';', 'asm' or 'attribute' before '{' token
class GPIOPin {
^
In file included from ../libnewgpio/hdr/GPIOAccess.h:13:0,
from sm_rotate.c:6:
../libnewgpio/hdr/GPIOPwmPin.h:10:1: error: unknown type name 'class'
class GPIOPwmPin {
^
../libnewgpio/hdr/GPIOPwmPin.h:10:18: error: expected '=', ',', ';', 'asm' or 'attribute' before '{' token
class GPIOPwmPin {
^
In file included from ../libnewgpio/hdr/GPIOAccess.h:14:0,
from sm_rotate.c:6:
../libnewgpio/hdr/GPIOIrqInfo.h:7:5: error: unknown type name 'GPIO_Irq_Type'
GPIO_Irq_Type type;
^
../libnewgpio/hdr/GPIOIrqInfo.h:9:5: error: unknown type name 'GPIO_Irq_Handler_Object'
GPIO_Irq_Handler_Object * handlerObj;
^
../libnewgpio/hdr/GPIOIrqInfo.h:10:5: error: unknown type name 'bool'
bool enabled;
^
In file included from ../libnewgpio/hdr/GPIOAccess.h:15:0,
from sm_rotate.c:6:
../libnewgpio/hdr/GPIOPulseInPin.h:7:1: error: unknown type name 'class'
class GPIOPulseInPin {
^
../libnewgpio/hdr/GPIOPulseInPin.h:7:22: error: expected '=', ',', ';', 'asm' or 'attribute' before '{' token
class GPIOPulseInPin {
^
In file included from sm_rotate.c:6:0:
../libnewgpio/hdr/GPIOAccess.h:21:1: error: unknown type name 'class'
class GPIOAccess {
^
../libnewgpio/hdr/GPIOAccess.h:21:18: error: expected '=', ',', ';', 'asm' or 'attribute' before '{' token
class GPIOAccess {
^
sm_rotate.c: In function 'main':
sm_rotate.c:14:2: error: unknown type name 'GPIOPin'
GPIOPin* pins[4];
^
sm_rotate.c:15:12: error: 'new' undeclared (first use in this function)
pins[0] = new GPIOPin(0);
^
sm_rotate.c:15:12: note: each undeclared identifier is reported only once for each function it appears in
sm_rotate.c:15:16: error: expected ';' before 'GPIOPin'
pins[0] = new GPIOPin(0);
^
sm_rotate.c:16:16: error: expected ';' before 'GPIOPin'
pins[1] = new GPIOPin(1);
^
sm_rotate.c:17:16: error: expected ';' before 'GPIOPin'
pins[2] = new GPIOPin(6);
^
sm_rotate.c:18:16: error: expected ';' before 'GPIOPin'
pins[3] = new GPIOPin(7);
^
sm_rotate.c:20:2: error: 'for' loop initial declarations are only allowed in C99 mode
for (int i = 0; i < 4; i++)
^
sm_rotate.c:20:2: note: use option -std=c99 or -std=gnu99 to compile your code
sm_rotate.c:22:10: error: request for member 'setDirection' in something not a structure or union
pins[i]->setDirection(GPIO_OUTPUT);
^
sm_rotate.c:25:6: error: redefinition of 'i'
int i = 0, j = 3;
^
sm_rotate.c:20:11: note: previous definition of 'i' was here
for (int i = 0; i < 4; i++)
^
sm_rotate.c:28:10: error: request for member 'set' in something not a structure or union
pins[i]->set(1);
^
sm_rotate.c:30:10: error: request for member 'set' in something not a structure or union
pins[j]->set(0);