saving

lib/p2/src/structures/pscopes.zig

@@ -4,7 +4,7 @@
 //
 // as well as contains info for arbitrary timestamping and timestamp resolution
 
-const timestampTicks = if (builtin.target.cpu.arch == .x86_64) aarch64_ticks else rdtsc;
+const timestampTicks = if (builtin.target.cpu.arch == .x86_64) rdtsc else aarch64_ticks;
 
 pub inline fn rdtsc_fenced() u64 {
     var hi: u32 = 0;
@@ -44,6 +44,12 @@ fn aarch64_freq() u64 {
     );
 }
 
+fn countTo1Billion() u32 {
+    var i: u32 = 0;
+    while (i < 1000 * 1000 * 1000) : (i += 1) {}
+    return i;
+}
+
 pub const TimingScope = struct {
     // value in tsc ticks
     startTsc: u64,
@@ -59,7 +65,14 @@ pub const TimingScope = struct {
     }
 
     pub fn duration(self: *@This()) ?f64 {
-        _ = self;
+        if (self.endTsc) |endTsc| {
+            if (self.context.ticksPerMs) |ticksPerMs| {
+                const x = @as(f64, @floatFromInt(endTsc - self.startTsc)) / ticksPerMs / 1000;
+                return x;
+            }
+        }
+
+        return null;
     }
 
     pub inline fn end(self: *@This()) void {
@@ -73,7 +86,11 @@ pub const ScopesContext = struct {
     timer: std.time.Timer,
 
     pub fn timingScope(self: *@This()) TimingScope {
-        _ = self;
+        return .{
+            .startTsc = timestampTicks(),
+            .endTsc = null,
+            .context = self,
+        };
     }
 
     // calibrates the ticks per second divider.
@@ -125,6 +142,14 @@ test "calibrate scoes" {
     std.debug.print("calibration ticksPerMs = {d}\n", .{scopes.ticksPerMs.?});
     scopes.calibrate();
     std.debug.print("calibration ticksPerMs = {d}\n", .{scopes.ticksPerMs.?});
+
+    {
+        var scope = scopes.timingScope();
+        _ = countTo1Billion();
+        scope.end();
+
+        std.debug.print("time elapsed: {d}\n ", .{scope.duration().?});
+    }
 }
 
 const std = @import("std");