raspberry: StateMachine: Add support for wrap=, wrap_target=

[jepler]

Together with adafruit/Adafruit_CircuitPython_PIOASM#35 this adds support for .wrap and .wrap_target pseudo-ops in pio programs. I've only compile-tested this code, though; it should be put through the paces before being used.

[jepler]

I finally got around to testing this. It works fine.

Test program:

import adafruit_pioasm
import rp2pio
import array

program = adafruit_pioasm.Program("""
        set x, 31 
        in x, 32 
        .wrap_target 
            jmp x--, f
        f:  
            in x, 32 
        .wrap 
            set x, 3
            in x, 32 
        """, build_debuginfo=True)

program.print_c_program("test")

b = array.array('L', [0]*6)
sm = rp2pio.StateMachine(program.assembled, **program.pio_kwargs, frequency=100_000_000, auto_push=True)
sm.readinto(b)

It should print array('L', [31, 30, 29, 28, 27, 26]), otherwise, the wrap is not taking effect correctly. For instance, if it printed [31, 30, 3, 31, 30, 3] then no wrapping is occurring. If the wrap or wrap target were off by one, the results would be different again.

[dhalbert]

Thanks!