Begin work on Atomics for wasm32 (wait and notify intrinsics)

core/intrinsics/intrinsics.odin

@@ -190,6 +190,15 @@ constant_utf16_cstring :: proc($literal: string) -> [^]u16 ---
 wasm_memory_grow :: proc(index, delta: uintptr) -> int ---
 wasm_memory_size :: proc(index: uintptr)        -> int ---
 
+// `timeout_ns` is maximum number of nanoseconds the calling thread will be blocked for
+// A negative value will be blocked forever
+// Return value:
+// 0 - indicates that the thread blocked and then was woken up
+// 1 - the loaded value from `ptr` did not match `expected`, the thread did not block
+// 2 - the thread blocked, but the timeout
+wasm_memory_atomic_wait32   :: proc(ptr: ^u32, expected: u32, timeout_ns: i64) -> u32 ---
+wasm_memory_atomic_notify32 :: proc(ptr: ^u32, waiters: u32) -> (waiters_woken_up: u32) ---
+
 
 // Darwin targets only
 objc_object   :: struct{}

core/sync/futex_wasm.odin

@@ -0,0 +1,36 @@
+//+private
+//+build wasm32
+package sync
+
+import "core:intrinsics"
+import "core:time"
+
+_futex_wait :: proc(f: ^Futex, expected: u32) -> bool {
+	s := intrinsics.wasm_memory_atomic_wait32((^u32)(f), expected, -1)
+	return s != 0
+}
+
+_futex_wait_with_timeout :: proc(f: ^Futex, expected: u32, duration: time.Duration) -> bool {
+	s := intrinsics.wasm_memory_atomic_wait32((^u32)(f), expected, i64(duration))
+	return s != 0
+
+}
+
+_futex_signal :: proc(f: ^Futex) {
+	loop: for {
+		s := intrinsics.wasm_memory_atomic_notify32((^u32)(f), 1)
+		if s >= 1 {
+			return
+		}
+	}
+}
+
+_futex_broadcast :: proc(f: ^Futex) {
+	loop: for {
+		s := intrinsics.wasm_memory_atomic_notify32((^u32)(f), ~u32(0))
+		if s >= 0 {
+			return
+		}
+	}
+}
+

core/sync/primitives_wasm.odin

@@ -0,0 +1,8 @@
+//+private
+//+build wasm32
+package sync
+
+_current_thread_id :: proc "contextless" () -> int {
+	// TODO(bill): _current_thread_id for wasm32
+	return 0
+}