k8055m_poll -- Wait for new input
k8055-pic18f access library
#include "k8055m.h" int k8055m_poll(int cardNumber);
The k8055m library uses a background thread to continuously read the HID reports, sent by the
k8055-pic18f card. This thread keeps track of all input port and counter changes. Functions like
k8055m_get_digital_in() therefore have instant access to the last known state of input data.
However, a code construct like
while (k8055m_get_digital_in(theCard, 0)) { ... }
will cause a busy loop, wasting an entire CPU core, until line I1 of theCard is released.
To avoid such busy loops, k8055m_poll() should be called in between reading the same
input ports. k8055m_poll() will immediately return, if the background thread has received
a new HID report from the card since its last call. It will wait for the next HID report otherwise.
Returns 0 on success, -1 on error.
There should be a mechanism to register a callback function, that is invoked on the arrival of new HID reports.