rapid taps cause a divide by zero in the multitouch device

[lemonjesus]

rapidly clicking the emulator (and sometimes randomly) causes a Floating Point Exception which, according to gdb, is caused by the following lines where elapsed_ns and s->last_frame_timestamp are the same so you get a divide by 0 error:

https://github.com/devos50/qemu/blob/7385a192485af58f975393fa04b69fea9300d492/hw/arm/ipod_touch_multitouch.c#L315-L316

I suppose you could check for this and increase elapsed_ns by 1 to avoid a crash, but I'm not sure what the implication of that would be in terms of timestamping and/or possibly glitchy movements.

[coreycusick]

I can confirm this seems to work. Touch seems accurate still. And it doesn't crash when rapid clicking.

frame->finger_data.velX = diff_x / (elapsed_ns+1 - s->last_frame_timestamp) * 1000; frame->finger_data.velY = diff_y / (elapsed_ns+1 - s->last_frame_timestamp) * 1000;

[preland]

I can confirm this happens; it will also happen when repeatedly clicking at slow speeds (<2 per second)

It also seems to be noticably more likely to crash during startup, but will still crash after startup if repeated clicking occurs