1 files changed, 161 insertions, 0 deletions
diff --git a/arm9/lib/src/FX_atan.c b/arm9/lib/src/FX_atan.c
new file mode 100644
index 00000000..979895a8
--- /dev/null
+++ b/arm9/lib/src/FX_atan.c
@@ -0,0 +1,161 @@
+#include "global.h"
+#include "main.h"
+#include "fx.h"
+
+extern fx16 FX_AtanTable_[];
+
+ARM_FUNC u16 FX_Atan(fx32 x){
+    if (x >= 0)
+    {
+        if (x > 0x1000)
+        {
+            x = FX_Inv(x);
+            fx16 y = FX_AtanTable_[x >> 5];
+            return 0x4000 - y;
+        }
+        else if (x < 0x1000)
+        {
+            return FX_AtanTable_[x >> 5];
+        }
+        else
+        {
+            return 0x2000;
+        }
+    }
+    else
+    {
+        if (x < -0x1000)
+        {
+            x = FX_Inv(-x);
+            fx16 y = FX_AtanTable_[x >> 5];
+            return y - 0x4000;
+        }
+        else if (x > -0x1000)
+        {
+            return -FX_AtanTable_[-x >> 5];
+        }
+        else
+        {
+            return -0x2000;
+        }
+    }
+}
+
+ARM_FUNC u16 FX_Atan2(fx32 x, fx32 y){
+    fx32 result;
+    u32 positive, bias, denominator, numerator;
+    if (x > 0)
+    {
+        if (y > 0)
+        {
+            if (y > x)
+            {
+                numerator = x;
+                denominator = y;
+                bias = 0;
+                positive = TRUE;
+            }
+            else if (y < x)
+            {
+                numerator = y;
+                denominator = x;
+                bias = 0x4000;
+                positive = FALSE;
+            }
+            else
+            {
+                return 0x2000;
+            }
+        }
+        else if (y < 0)
+        {
+            y = -y;
+            if (y < x)
+            {
+                numerator = y;
+                denominator = x;
+                bias = 0x4000;
+                positive = TRUE;
+            }
+            else if (y > x)
+            {
+                numerator = x;
+                denominator = y;
+                bias = 0x8000;
+                positive = FALSE;
+            }
+            else
+            {
+                return 0x6000;
+            }
+        }
+        else
+        {
+            return 0x4000;
+        }
+    }
+    else if (x < 0)
+    {
+        x = -x;
+        if (y < 0)
+        {
+            y = -y;
+            if (y > x)
+            {
+                numerator = x;
+                denominator = y;
+                bias = -0x8000;
+                positive = TRUE;
+            }
+            else if (y < x)
+            {
+                numerator = y;
+                denominator = x;
+                bias = -0x4000;
+                positive = FALSE;
+            }
+            else
+            {
+                return 0xA000;
+            }
+        }
+        else if (y > 0)
+        {
+            if (y < x)
+            {
+                numerator = y;
+                denominator = x;
+                bias = -0x4000;
+                positive = TRUE;
+            }
+            else if (y > x)
+            {
+                numerator = x;
+                denominator = y;
+                bias = 0x0;
+                positive = FALSE;
+            }
+            else
+            {
+                return 0xE000;
+            }
+        }
+        else
+        {
+            return 0xC000;
+        }
+    }
+    else
+    {
+        if (y >= 0)
+            return 0x0;
+        else
+            return 0x8000;
+    }
+    if (denominator == 0x0)
+        return 0x0;
+    if (positive)
+        return bias + FX_AtanTable_[FX_Div(numerator, denominator) >> 5];
+    else
+        return bias - FX_AtanTable_[FX_Div(numerator, denominator) >> 5];
+}