Secondary Stack in Cortex GNAT RTS

In GNAT, the secondary stack is a construct used with indeterminate types. For example, if a function returns a String, it isn't possible for the caller to determine how much space to reserve for the result: instead, the called function allocates the amount of space required on the secondary stack, and on return the caller determines how much space to allocate on the normal (primary) stack, and pops the function's result from the secondary stack to there.

This note discusses how the secondary stack is managed in Cortex GNAT RTS for FSF GCC and GNAT Community Edition (was GNAT GPL).

Dependency plot

I wanted to get a dependency graph for a project, and found DePlo (Dependency Plotter). Great stuff, last updated in 2012 but still works with FSF GCC 8.0.1!

This sample is from my Analytical Engine project:

Tcl/Tk vs Trampolines

This is a note on a problem I encountered while working on the House Management example domain in my ColdFrame project.
TL;DR: If you write a Tcl callback function in Ada, declare it at library level.

Controlling a Crazyflie

This is a note on getting set up to work on a Crazyflie 2.0.

After unpacking, testing and assembling the drone, you need to get some software to talk to it.

GDB vs macOS Sierra

We probably feel downhearted if we need to use the debugger to find out what's wrong with our Ada code.

Under those circumstances, we feel even more frustrated if the debugger doesn't work!

This is exactly what has happened with gdb and macOS Sierra.

MPU9250, continued

This is a note on building support for the MPU9250 9-axis chip in the AdaPilot project (the AdaRacer hardware). It continues this report.

Invensense MPU9250 via SPI

This is a note on building support for the MPU9250 9-axis chip in the AdaPilot project (the AdaRacer hardware; the prototype board I have is subtly different from the one shown).
9-axis means it can measure each of acceleration, gyro and magnetic field values in 3 axes, which is very useful if your drone needs to know about its own motion.