RSDL Joystick

'''
Joystick RSDL Extension, by Brett
goatman.py@gmail.com
license BSD

Interfacing RPython with C
The documentation on how to interface RPython with C is rather limited, the extending doc mentions that `MixedModules` using rffi is the most advanced method available.  The rffi document only provides a quick glance at how to use rffi.llexternal.  The best place to get started is looking at the source code in rlib/rsdl/RSDL.py which binds RPython to SDL.  What should be clear after reading RSDL.py is that PyPy provides a very direct and easy to understand interface for C; that should also provide the highest possible performance.

The source code in rffi_platform.py (found in pypy/rpython/tool) is very interesting, it generates dynamic C code that it compiles to get information about the C code we are trying to wrap, for example if you had used the wrong name in a struct it will generate an error.  Using rffi_platform different C types can be defined, such as structs, constant integers; these are then put into a special container class called CConfig, which is then parsed by rffi_platform.configure(CConfig) and wrappers returned.  After we have the wrappers we must tell any pointers we had previously used in the CConfig that they `become` those objects, MyPointer.TO.become(MyStruct).

RSDL that is included in PyPy is incomplete and lacks wrappers for Joystick, the code below wraps SDL Joystick.
'''
PATH2PYPY = 'pypy'

import sys, math, time
sys.path.append(PATH2PYPY)
from pypy.rlib.objectmodel import specialize
from pypy.rpython.lltypesystem import lltype, rffi
from pypy.rpython.tool import rffi_platform as platform
from pypy.rlib.rsdl import RSDL, RSDL_helper
from pypy.rlib.rsdl.eci import get_rsdl_compilation_info

eci = get_rsdl_compilation_info()
## wrapper for rffi.llexternal just to shorten the call
def external(name, args, result): return rffi.llexternal(name, args, result, compilation_info=eci)

JoystickPtr = lltype.Ptr(lltype.ForwardReference())
JoyAxisEventPtr = lltype.Ptr(lltype.ForwardReference())
JoyBallEventPtr = lltype.Ptr(lltype.ForwardReference())
JoyButtonEventPtr = lltype.Ptr(lltype.ForwardReference())
JoyHatEventPtr = lltype.Ptr(lltype.ForwardReference())


class CConfig:
    _compilation_info_ = eci
    Joystick = platform.Struct('SDL_JoyAxisEvent', [])      # just and ID, struct contains nothing
    # rsdl/constants.py already defines SDL_JOYAXISMOTION, SDL_JOYBALLMOTION, etc..
    JoyAxisEvent = platform.Struct('SDL_JoyAxisEvent',
            [('type', rffi.INT),
            ('which', rffi.INT),
            ('axis', rffi.INT),
            ('value', rffi.INT)])
    JoyBallEvent = platform.Struct('SDL_JoyBallEvent',
            [('type', rffi.INT),
            ('which', rffi.INT),
            ('ball', rffi.INT),
            ('xrel', rffi.INT), ('yrel', rffi.INT)])
    JoyButtonEvent = platform.Struct('SDL_JoyButtonEvent',
            [('type', rffi.INT),
            ('which', rffi.INT),
            ('button', rffi.INT),
            ('state', rffi.INT)])       # SDL_PRESSED or SDL_RELEASED
    JoyHatEvent = platform.Struct('SDL_JoyHatEvent',
            [('type', rffi.INT),
            ('which', rffi.INT),
            ('hat', rffi.INT),
            ('value', rffi.INT)])       # SDL_HAT_*

CONSTS = 'INIT_JOYSTICK QUERY ENABLE IGNORE PRESSED RELEASED'
#hat already in rsdl/constants.py#HAT_CENTERED HAT_UP HAT_RIGHT HAT_DOWN HAT_LEFT HAT_RIGHTUP HAT_RIGHTDOWN HAT_LEFTUP HAT_LEFTDOWN'
for name in CONSTS.split():
    name = name.strip()
    if name:
        ci = platform.ConstantInteger('SDL_%s' %name)
        setattr( CConfig, name, ci )
globals().update(platform.configure(CConfig))

JoystickPtr.TO.become(Joystick)
JoyAxisEventPtr.TO.become(JoyAxisEvent)
JoyBallEventPtr.TO.become(JoyBallEvent)
JoyButtonEventPtr.TO.become(JoyButtonEvent)
JoyHatEventPtr.TO.become(JoyHatEvent)

#Updates the state(position, buttons, etc.) of all open joysticks.
#If joystick events have been enabled with SDL_JoystickEventState then this is called automatically in the event loop.
JoystickUpdate = external('SDL_JoystickUpdate', [], lltype.Void)
NumJoysticks = external('SDL_NumJoysticks', [], rffi.INT)
## CCHARP seems to stand for C char pointer ##
JoystickName = external('SDL_JoystickName', [rffi.INT], rffi.CCHARP)
JoystickOpen = external('SDL_JoystickOpen', [rffi.INT], JoystickPtr)
JoystickOpened = external('SDL_JoystickOpened', [rffi.INT], rffi.INT)
JoystickIndex = external('SDL_JoystickIndex', [JoystickPtr], rffi.INT)
JoystickNumAxes = external('SDL_JoystickNumAxes', [JoystickPtr], rffi.INT)
JoystickNumBalls = external('SDL_JoystickNumBalls', [JoystickPtr], rffi.INT)
JoystickNumHats = external('SDL_JoystickNumHats', [JoystickPtr], rffi.INT)
JoystickNumButtons = external('SDL_JoystickNumButtons', [JoystickPtr], rffi.INT)
JoystickGetAxis = external('SDL_JoystickGetAxis', [JoystickPtr,rffi.INT], rffi.INT)     # 16bit signed integer (-32768 to 32768)
JoystickGetHat = external('SDL_JoystickGetHat', [JoystickPtr,rffi.INT], rffi.INT)       # Uint8
JoystickGetButton = external('SDL_JoystickGetButton', [JoystickPtr,rffi.INT], rffi.INT)     # Uint8
# is this correct?
#JoystickBallXPtr = lltype.Ptr(lltype.ForwardReference())
#JoystickBallYPtr = lltype.Ptr(lltype.ForwardReference())
#int SDL_JoystickGetBall(SDL_Joystick *joystick, int ball, int *dx, int *dy);
#JoystickGetBall = external('SDL_JoystickGetBall', [JoystickPtr,rffi.INT, JoystickBallXPtr, JoystickBallYPtr], rffi.INT)        # Uint8
JoystickClose = external('SDL_JoystickClose', [JoystickPtr], lltype.Void)       # Uint8
#This function is used to enable or disable joystick event processing. With joystick event processing disabled you will have to update joystick states with SDL_JoystickUpdate and read the joystick information manually. state is either SDL_QUERY, SDL_ENABLE or SDL_IGNORE.
JoystickEventState = external('SDL_JoystickEventState', [rffi.INT], rffi.INT)

def handle_event( etype, event ):
    if etype == RSDL.JOYAXISMOTION:
        p = rffi.cast( JoyAxisEventPtr, event )
        axis = rffi.getintfield(p, 'c_axis')
        value = rffi.getintfield(p, 'c_value')
        print 'axis: %s value: %s' %(axis, value)

    elif etype == RSDL.JOYBALLMOTION:
        p = rffi.cast( JoyBallEventPtr, event )
        ball = rffi.getintfield(p, 'c_ball')
        x = rffi.getintfield(p, 'c_xrel')
        y = rffi.getintfield(p, 'c_yrel')
        print 'ball: %s x: %s y: %s' %(ball, x,y)

    elif etype == RSDL.JOYHATMOTION:
        p = rffi.cast( JoyHatEventPtr, event )
        hat = rffi.getintfield(p, 'c_hat')
        value = rffi.getintfield(p, 'c_value')
        print 'hat: %s value: %s' %(hat, value)

    elif etype in ( RSDL.JOYBUTTONDOWN, RSDL.JOYBUTTONUP ):
        p = rffi.cast( JoyButtonEventPtr, event )
        but = rffi.getintfield(p, 'c_button')
        state = rffi.getintfield(p, 'c_state')
        print 'button: %s state: %s' %(but, state)


def poll(loops=1000):
    event = lltype.malloc(RSDL.Event, flavor='raw')
    try:
        i = 1
        while i < loops:
            ok = RSDL.PollEvent(event); ok = rffi.cast(lltype.Signed, ok)
            assert ok >= 0
            if ok > 0: c_type = rffi.getintfield(event, 'c_type'); handle_event( c_type, event )
            time.sleep(0.01)
            i += 1
    finally: lltype.free(event, flavor='raw')

def test():
    assert RSDL.Init(INIT_JOYSTICK | RSDL.INIT_VIDEO ) >= 0
    num = NumJoysticks(); print 'number of joysticks/gamepads: %s' %num
    JoystickEventState( RSDL.ENABLE )
    if num:
        joy = JoystickOpen( 0 )
        numaxes = JoystickNumAxes( joy ); print 'number of axes: %s' %numaxes
        numbut = JoystickNumButtons( joy ); print 'number of buttons: %s' %numbut
        poll()

if __name__ == '__main__':
    from pypy.translator.interactive import Translation
    t = Translation( test )
    t.annotate(); t.rtype()
    entrypoint = t.compile_c()
    entrypoint()