From 778fe214d136efeda7d072f933a0cf8ff1840f85 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Tue, 27 Apr 2021 14:41:49 +0200
Subject: Testing BIOS calls

---
 Makefile         |  4 +++-
 src/bios_calls.s |  9 +++++++++
 src/main.c       | 48 +++++++++++++++++++++---------------------------
 3 files changed, 33 insertions(+), 28 deletions(-)
 create mode 100644 src/bios_calls.s

diff --git a/Makefile b/Makefile
index 1979bf8..7202bb9 100644
--- a/Makefile
+++ b/Makefile
@@ -14,8 +14,10 @@ LIBGBA     += $(LIBGBA_DIR)/lib/libmm.a
 # Source code location and files to watch for changes.
 SRC_DIR        := src
 SRC_MAIN       := $(SRC_DIR)/main.c
+ASM_FILES      := $(wildcard $(SRC_DIR)/*.s)
 WATCH_SRC      := $(wildcard $(SRC_DIR)/*.c)
 WATCH_SRC      += $(wildcard $(SRC_DIR)/*.h)
+WATCH_SRC      += $(wildcard $(SRC_DIR)/*.s)
 
 # Output library names and executables.
 TARGET         := experiments
@@ -57,7 +59,7 @@ $(BIN): $(ELF)
 
 # Link files.
 $(ELF): $(SRC_MAIN) $(WATCH_SRC)
-	$(CC) $(CFLAGS) $(LDFLAGS) -o $(ELF) $(SRC_MAIN) $(LDLIBS)
+	$(CC) $(CFLAGS) $(LDFLAGS) -o $(ELF) $(SRC_MAIN) $(ASM_FILES) $(LDLIBS)
 
 # Create build directory if needed.
 $(BUILD_DIR):
diff --git a/src/bios_calls.s b/src/bios_calls.s
new file mode 100644
index 0000000..2268b4d
--- /dev/null
+++ b/src/bios_calls.s
@@ -0,0 +1,9 @@
+@ Bios division call.
+    .text           @ aka .section .text
+    .code 16        @ aka .thumb
+    .align 2        @ aka .balign 4
+    .global bios_div
+    .thumb_func
+bios_div:
+    swi     0x06
+    bx      lr
diff --git a/src/main.c b/src/main.c
index 88bc3b8..decd40d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -13,6 +13,16 @@
 // TODO: Cleanup OBJ/OAM memory copying and access.
 //
 
+//
+// BIOS calls
+//
+
+int bios_div(int num, int denom);
+
+int normal_div(int num, int denom) {
+    return num / denom;
+};
+
 int main(void) {
     // Configure the display in mode 0 to show OBJs, where tile memory is
     // sequential.
@@ -22,42 +32,26 @@ int main(void) {
     init_sprite_pal(0, COLOR_WHITE);
     init_sprites(0);
     init_button_sprites();
-    Color colors[16] = {
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-        COLOR_BLUE,
-    };
 
-    size_t n_iter = 10000;
+    // Initialize text engine.
+    txt_init(0, COLOR_RED, 0);
+
+    size_t n_iter = 1000;
     profile_start();
+    int test = 0;
     for (size_t i = 0; i < n_iter; ++i) {
-        dma_copy(&PAL_BUFFER_SPRITES[0], colors, 16 * sizeof(Color), 3);
+        txt_printf("Bios div:   %d\n", bios_div(5 * i, 5));
     }
-    u32 dma_copy_perf = profile_stop();
+    u32 bios_div_perf = profile_stop();
 
     profile_start();
     for (size_t i = 0; i < n_iter; ++i) {
-        memcpy(&PAL_BUFFER_SPRITES[0], colors, 16 * sizeof(Color));
+        txt_printf("Code div:   %d\n", normal_div(5 * i, 5));
     }
-    u32 memcpy_perf = profile_stop();
+    u32 code_perf = profile_stop();
 
-    // Initialize text engine.
-    txt_init(0, COLOR_RED, 0);
-    txt_printf("N. cycles memcpy:   %d\n", memcpy_perf);
-    txt_printf("N. cycles dma_copy: %d\n", dma_copy_perf);
+    txt_printf("C code div perf:   %d\n", code_perf);
+    txt_printf("BIOS div perf:     %d\n", bios_div_perf);
 
     int frame_counter = 0;
     while(true) {
-- 
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