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Added info on address arbiters
== Light Event ==
== Light Event ==
== Address Arbiters ==
Address arbiters are a low-level primitive to implement synchronization based on a counter stored at some user-specified virtual memory address. Address arbiters are used to put the current thread to sleep until the counter is signaled. Both of these tasks are implemented in ArbitrateAddress.
===CreateAddressArbiter===
Result CreateAddressArbiter(Handle* arbiter)
Creates an address arbiter handle for use with ArbitrateAddress.
=== ArbitrateAddress ===
Result ArbitrateAddress(Handle arbiter, u32 addr, ArbitrationType type, s32 value, s64 nanoseconds)
if <code>type</code> is SIGNAL, the ArbitrateAddress call will resume up to <code>value</code> of the threads waiting on <code>addr</code> using an arbiter, starting with the highest-priority threads. If <code>value</code> is negative, all of these threads are released. <code>nanoseconds</code> remains unused in this mode.
The other modes are used to (conditionally) put the current thread to sleep based on the memory word at virtual address <code>addr</code> until another thread signals that address using ArbitrateAddress with the <code>type</code> SIGNAL. WAIT_IF_LESS_THAN will put the current thread to sleep if that word is smaller than <code>value</code>. DECREMENT_AND_WAIT_IF_LESS_THAN will furthermore decrement the memory value before the comparison. WAIT_IF_LESS_THAN_TIMEOUT and DECREMENT_AND_WAIT_IF_LESS_THAN_TIMEOUT will do the same as their counterparts, but will have thread execution resume if <code>nanoseconds</code> nanoseconds pass without <code>addr</code> being signaled.
=== enum ArbitrationType ===
{| class="wikitable" border="1"
! Address arbitration type
! Value
|-
| SIGNAL
| 0
|-
| WAIT_IF_LESS_THAN
| 1
|-
| DECREMENT_AND_WAIT_IF_LESS_THAN
| 2
|-
| WAIT_IF_LESS_THAN_TIMEOUT
| 3
|-
| DECREMENT_AND_WAIT_IF_LESS_THAN_TIMEOUT
| 4
|}