sylveos

commit 9beb46c3b84eb98217324f06fb4a752e23665930
parent 46947c53efa2dd716ba099327a0515215edd40dd
Author: Sylvia Ivory <git@sivory.net>
Date:   Thu, 22 Jan 2026 20:15:55 -0800

Add profiler lab (needs new root)

Diffstat:
M
src/devices/timer.zig
 | 
4
++++
A
src/labs/4-profiler.zig
 | 
55
+++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
src/main.zig
 | 
45
+--------------------------------------------

3 files changed, 60 insertions(+), 44 deletions(-)
diff --git a/src/devices/timer.zig b/src/devices/timer.zig
@@ -100,6 +100,10 @@ noinline fn timer_handler(pc: usize) void {
     mem.barrier(.Write); // Sync before restoring
 }
 
+pub inline fn set_tick(tick: *const fn (usize) void) void {
+    tick_fn = tick;
+}
+
 pub inline fn get_count() u32 {
     return count;
 }
diff --git a/src/labs/4-profiler.zig b/src/labs/4-profiler.zig
@@ -0,0 +1,55 @@
+const std = @import("std");
+const interrupts = @import("pi").interrupts;
+
+const uart = @import("devices/mini-uart.zig");
+const clock = @import("devices/clock.zig");
+const timer = @import("devices/timer.zig");
+
+// 1Mb
+var buffer: [1024 * 1024]u8 = undefined;
+var fba: std.heap.FixedBufferAllocator = undefined;
+var hist: std.AutoHashMap(usize, usize) = undefined;
+var enabled = true;
+
+extern const __code_start__: u32;
+extern const __code_end__: u32;
+
+fn tick(pc: usize) void {
+    if (!enabled) return;
+
+    const res = hist.getOrPutValue(pc, 0) catch unreachable;
+    const new_value = res.value_ptr.* + 1;
+
+    hist.put(pc, new_value) catch unreachable;
+}
+
+fn dump(min: usize) void {
+    enabled = false;
+    uart.writer.print("call profile:\n", .{}) catch {};
+    var iterator = hist.iterator();
+
+    while (iterator.next()) |entry| {
+        if (entry.value_ptr.* < min) continue;
+        uart.writer.print("  0x{X}: {d}\n", .{ entry.key_ptr.*, entry.value_ptr.* }) catch {};
+    }
+    enabled = true;
+}
+
+pub fn main() !void {
+    timer.initialize(.Sixteen, 0x100);
+    timer.set_tick(tick);
+
+    fba = .init(&buffer);
+    hist = .init(fba.allocator());
+
+    interrupts.enable_interrupts();
+
+    var iter: usize = 0;
+    while (timer.get_count() < 200) {
+        try uart.writer.print("iter={d}: count = {d}, period = {d}us, 0x{x}\n", .{ iter, timer.get_count(), timer.get_period(), timer.get_period() });
+        iter += 1;
+        if (iter % 10 == 0) {
+            dump(2);
+        }
+    }
+}
diff --git a/src/main.zig b/src/main.zig
@@ -1,44 +1 @@
-const interrupts = @import("pi").interrupts;
-
-const uart = @import("devices/mini-uart.zig");
-const clock = @import("devices/clock.zig");
-const timer = @import("devices/timer.zig");
-
-pub fn main() !void {
-    try uart.writer.print("entered main safely...\n", .{});
-
-    timer.initialize(.Sixteen, 0x100);
-
-    try uart.writer.print("initialized timer...\n", .{});
-
-    interrupts.enable_interrupts();
-
-    try uart.writer.print("enabled interrupts...\n", .{});
-
-    const start = clock.current_count();
-    var iter: u32 = 0;
-    const N = 20;
-
-    while (timer.get_count() < N) {
-        try uart.writer.print("iter={d}: count={d}, time between interrupts = {d} usec (0x{x})\n", .{
-            iter,
-            timer.get_count(),
-            timer.get_period(),
-            timer.get_period(),
-        });
-        iter += 1;
-    }
-
-    const total = clock.current_count() - start;
-    const total_sec = total / (1000 * 1000);
-    const total_ms = (total / 1000) % 10000;
-    const total_us = (total % 1000);
-
-    try uart.writer.print(
-        \\ total iterations: {}
-        \\ total interrupts: {}
-        \\ iterations / interrupt: {}
-        \\ average period: {}
-        \\ total execution time: {}s.{}ms.{}us
-    , .{ iter, N, iter / N, timer.get_period_sum() / (N - 1), total_sec, total_ms, total_us });
-}
+fn main() void {}