EM4x50 simulation (Not complete yet)

[Shanti67]

Add EM4x50 simulation (Not complete yet)

[holiman]

I don't know if it's ready to merge, as it says "not complete yet" ?
Also, could you try to abstract away a bit from the loops, things like:

period += T0*EM4x50_T_HALF_PERIOD;
LOW(GPIO_SSC_DOUT);
while (AT91C_BASE_TC0->TC_CV < period);
period += T0 * 3 * EM4x50_T_HALF_PERIOD;
HIGH(GPIO_SSC_DOUT);
while (AT91C_BASE_TC0->TC_CV < period);
period += T0 * EM4x50_T_HALF_PERIOD;
LOW(GPIO_SSC_DOUT);
while (AT91C_BASE_TC0->TC_CV < period);
period += T0 * 3 * EM4x50_T_HALF_PERIOD;
HIGH(GPIO_SSC_DOUT);
while (AT91C_BASE_TC0->TC_CV < period);
period += T0 * EM4x50_T_HALF_PERIOD;
LOW(GPIO_SSC_DOUT);
while (AT91C_BASE_TC0->TC_CV < period);

And instead move that into some function so it's easier on the eyes. Something like this:

em4x_mod_high(1)
em4x_mod_low(1)
em4x_mod_high(3)

(Note: I haven't actually dug deep enough to know if my sample code above makes sense, but something like it should work )