spall instrumentation

core/prof/spall/spall_windows.odin

@@ -0,0 +1,53 @@
+//+private
+package spall
+
+// Only for types.
+import "core:os"
+
+// Package is `//+no-instrumentation`, safe to use.
+import win32 "core:sys/windows"
+
+MAX_RW :: 1<<30
+
+@(no_instrumentation)
+_write :: proc "contextless" (fd: os.Handle, data: []byte) -> (int, os.Errno) #no_bounds_check /* bounds check would segfault instrumentation */ {
+	if len(data) == 0 {
+		return 0, os.ERROR_NONE
+	}
+
+	single_write_length: win32.DWORD
+	total_write: i64
+	length := i64(len(data))
+
+	for total_write < length {
+		remaining := length - total_write
+		to_write := win32.DWORD(min(i32(remaining), MAX_RW))
+
+		e := win32.WriteFile(win32.HANDLE(fd), &data[total_write], to_write, &single_write_length, nil)
+		if single_write_length <= 0 || !e {
+			err := os.Errno(win32.GetLastError())
+			return int(total_write), err
+		}
+		total_write += i64(single_write_length)
+	}
+	return int(total_write), os.ERROR_NONE
+}
+
+@(no_instrumentation)
+_tick_now :: proc "contextless" () -> (ns: i64) {
+	mul_div_u64 :: #force_inline proc "contextless" (val, num, den: i64) -> i64 {
+		q := val / den
+		r := val % den
+		return q * num + r * num / den
+	}
+
+	@thread_local qpc_frequency: win32.LARGE_INTEGER
+
+	if qpc_frequency == 0 {
+		win32.QueryPerformanceFrequency(&qpc_frequency)
+	}
+	now: win32.LARGE_INTEGER
+	win32.QueryPerformanceCounter(&now)
+
+	return mul_div_u64(i64(now), 1e9, i64(qpc_frequency))
+}