espsim

ESP8266 Simulator (Allows Native Code to Link/Run on Linux)

Allows native esp8266 code to be be cross-compiled to run native 32 bit executable on a host computer (currently linux) .. not to be confused with using the xtensa cross-compiler to create a native esp8266 image that can only be run on an esp8266 cpu.

<p> I am releasing this because it has proven useful for me and has become integral to my development process because I can run a native Linux executable that will communicate with actual esp8266 processors. <p> <ol> <li>Note, this was only used against a single application and it was done quick & dirty to get it to bootstrap and run. Mileage will vary.</li> <li>This is not production level code, there are likely gaps and potential differences in my implementation relative to embedded code.</li> <li>If your not that experienced with C/C++, you might want to wait and see if this project matures some before trying to get it to port.</li> <li>Porting to other platforms may be a little involved (network.cpp), I will likely do a mac port, not too motivated on cygwin.</li> <li>Looking for contributions, with a little work and more testing, this could become useful for a lot more people.</li> </ol> <h2>The Good</h2>

I was able to use this to do some unit/stress testing on some embedded code using valgrind. Later I added the espconn networking support so I could again use valgrind with much further coverage. Currently I use this for networking/application code before flashing to an embedded device.

<ul> <li>Allows esp8266 code to be run with native tools like gdb and valgrind.</li> <li>Networking is implemented allowing a native esp8266 process to blend with networked devices.</li> <li>Emulation of flash and rtc memory storage implemented in a way to fail fast on boundary errors.</li> <li>Limited options for setting the heap size, tracking memory allocations/frees, and tracing network.</li> <li>Provides an esp.h header file that works on Linux and for esp8266 c++ code</li> <li>Was developed using the 1.2.0 sdk, and works equally well with 1.3.0.</li> <li>A C++ compliant esp.h that has all the missing prototypes I ran into so far</li> </ul> <h2>The Bad</h2>

There are some issues getting this to work, mostly because this needs to be built using a 32-bit environment..

<ul> <li>The esp8266 is 32 bit, so compiling on a 64-bit host caused several issues with sizes of longs and pointers.</li> <li>The system task post arg is defined as a 32 bit value, you can set it to a pointer since they are also 32 bits, not on 64-bit os.</li> <li>Definitely does not handle simulation of off-chip devices, more suited for testing systems programming code.</li> <li>Had to make a couple of manual changes to the esp8266 header files to make this work correctly.</li> <li>Has not been ported to any other platforms other than a 64-bit ubuntu/mint installation.</li> <li>Need to add this function to your code in order to get tty input: void uart_hook(char ch) {}</li> <li>valgrind reports some issues in my networking code at shutdown, should clean that up. <li>Probably needs a ton more options to set/override runtime defaults. </ul> <h2>The Ugly</h2>

I run 64-bit Ubuntu/Mint environment system, and has had a lot of packages already installed at this point. You could use virtualbox to run a 32-bit environment, or what I did was carefully add i386 libraries until I got it to link. Looking through packages installed I see libc6-dev-i386, libc6-i386, g++-4.8-multilib, valgrind-i386 (removes the 64 bit version!).

<p> Be careful of anything that wants to replace all of your shared libraries with 32 bit versions. <p> Maybe it can work on a 64-bit install but the required changes looked a little more daunting. <p> The following headers were changed: <h3>eagle_soc.h</h3>

Around line 45, change the following to stop the gpio calls from segfaulting:

<p> <pre> #define ETS_UNCACHED_ADDR(addr) (addr) #define ETS_CACHED_ADDR(addr) (addr) </pre> <p>with:</p> <p> <pre> // LINUX #ifndef ETS_UNCACHED_ADDR #define ETS_UNCACHED_ADDR(addr) (addr) #endif

#ifndef ETS_CACHED_ADDR #define ETS_CACHED_ADDR(addr) (addr) #endif </pre>

<h3>c_types.h</h3> <p>Replace</p> <p> <pre> typedef signed long int32_t; </pre> <p>with:</p> <p> <pre> #ifndef __uint32_t_defined typedef signed long int32_t; #endif </pre>