From fb4a3111051bc63b202fe2b43582d8d39c9d237e Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Fri, 16 Apr 2021 11:10:19 +0200
Subject: Add profiling code and test with m4 vs m3 drawing

---
 src/main.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 72 insertions(+), 10 deletions(-)

diff --git a/src/main.c b/src/main.c
index 720f77e..d76273a 100644
--- a/src/main.c
+++ b/src/main.c
@@ -37,11 +37,11 @@
 #define DISP_MODE_5 0x0005
 
 // Layers.
-#define DISP_BG0 0x0100
-#define DISP_BG1 0x0200
-#define DISP_BG2 0x0400
-#define DISP_BG3 0x0800
-#define DISP_OBJ 0x1000
+#define DISP_BG_0 0x0100
+#define DISP_BG_1 0x0200
+#define DISP_BG_2 0x0400
+#define DISP_BG_3 0x0800
+#define DISP_OBJ  0x1000
 
 // Screen settings.
 #define SCREEN_WIDTH 240
@@ -265,8 +265,49 @@ flip_page() {
 #define SCREEN_PAGE_1 ((vu16*) MEM_VRAM)
 #define SCREEN_PAGE_2 ((vu16*) (MEM_VRAM + 0xa000))
 
+//
+// Profiling.
+//
+
+#define TIMER_DATA_0  *((vu16*) (0x04000100 + 0x04 * 0))
+#define TIMER_DATA_1  *((vu16*) (0x04000100 + 0x04 * 1))
+#define TIMER_DATA_2  *((vu16*) (0x04000100 + 0x04 * 2))
+#define TIMER_DATA_3  *((vu16*) (0x04000100 + 0x04 * 3))
+#define TIMER_CTRL_0  *((vu16*) (0x04000102 + 0x04 * 0))
+#define TIMER_CTRL_1  *((vu16*) (0x04000102 + 0x04 * 1))
+#define TIMER_CTRL_2  *((vu16*) (0x04000102 + 0x04 * 2))
+#define TIMER_CTRL_3  *((vu16*) (0x04000102 + 0x04 * 3))
+
+// Timer control bits.
+#define TIMER_CTRL_FREQ_0   0
+#define TIMER_CTRL_FREQ_1   1
+#define TIMER_CTRL_FREQ_2   2
+#define TIMER_CTRL_FREQ_3   3
+#define TIMER_CTRL_CASCADE (1 << 2)
+#define TIMER_CTRL_IRQ     (1 << 6)
+#define TIMER_CTRL_ENABLE  (1 << 7)
+
+// We use timers 2 and 3 to count the number of cycles since the profile_start
+// functions is called. Don't use if the code we are trying to profile make use
+// of these timers.
+static inline
+void profile_start() {
+    TIMER_DATA_2 = 0;
+    TIMER_DATA_3 = 0;
+    TIMER_CTRL_2 = 0;
+    TIMER_CTRL_3 = 0;
+    TIMER_CTRL_3 = TIMER_CTRL_ENABLE | TIMER_CTRL_CASCADE;
+    TIMER_CTRL_2 = TIMER_CTRL_ENABLE;
+}
+
+static inline
+u32 profile_stop() {
+   TIMER_CTRL_2 = 0;
+   return (TIMER_DATA_3 << 16) | TIMER_DATA_2;
+}
+
 int main(void) {
-    DISP_CONTROL = DISP_MODE_4 | DISP_BG2;
+    DISP_CONTROL = DISP_MODE_4 | DISP_BG_2;
 
     PAL_BUFFER[1] = COLOR_RED;
     PAL_BUFFER[2] = COLOR_BLUE;
@@ -276,13 +317,34 @@ int main(void) {
     draw_fill_rect_m4(0, 0, 20, 20, 1, SCREEN_PAGE_1);
     draw_fill_rect_m4(0, 0, 20, 20, 2, SCREEN_PAGE_2);
 
+    // Profile mode 4 vs mode 3 drawing fill_rects.
+    int n_iterations = 1000;
+    profile_start();
+    for (size_t i = 0; i < n_iterations; ++i) {
+        draw_fill_rect_m4(0, 0, 20, 20, 1, SCREEN_PAGE_1);
+    }
+    u32 mode_4_count = profile_stop();
+
+    DISP_CONTROL = DISP_MODE_3 | DISP_BG_2;
+    profile_start();
+    for (size_t i = 0; i < n_iterations; ++i) {
+        draw_fill_rect(0, 0, 20, 20, 1);
+    }
+    u32 mode_3_count = profile_stop();
+
+    char msg[240];
+    sprintf(&msg, "m4: %u", mode_4_count);
+    put_text(0, 0, COLOR_RED, msg);
+    sprintf(&msg, "m3: %u", mode_3_count);
+    put_text(0, 16, COLOR_RED, msg);
+
     int frame_counter = 0;
     while(true) {
         wait_vsync();
-        if (frame_counter++ > 30) {
-            frame_counter = 0;
-            flip_page();
-        }
+        // if (frame_counter++ > 30) {
+        //     frame_counter = 0;
+        //     flip_page();
+        // }
     };
 
     return 0;
-- 
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