This patch consolidates all global variables in py/ core into one place,
in a global structure. Root pointers are all located together to make
GC tracing easier and more efficient.
This allows to implement KeyboardInterrupt on unix, and a much safer
ctrl-C in stmhal port. First ctrl-C is a soft one, with hope that VM
will notice it; second ctrl-C is a hard one that kills anything (for
both unix and stmhal).
One needs to check for a pending exception in the VM only for jump
opcodes. Others can't produce an infinite loop (infinite recursion is
caught by stack check).
Blanket wide to all .c and .h files. Some files originating from ST are
difficult to deal with (license wise) so it was left out of those.
Also merged modpyb.h, modos.h, modstm.h and modtime.h in stmhal/.
Using PendSV interrupt at lowest priority, code can now raise an
exception during an interrupt by calling pendsv_nlr_jump. The exception
will be raised when all interrupts are finished. This is used to trap
ctrl-C from the USB VCP to break out of running Python code.
Dave Curtis
Dave Hylands
Damien George
Paul Sokolovsky