From ddf61363a18e7e9677e8dbd524374aa8dcd09cd6 Mon Sep 17 00:00:00 2001
From: Hayden Kowalchuk <819028+mrneo240@users.noreply.github.com>
Date: Thu, 5 Mar 2020 14:58:06 -0500
Subject: [PATCH] feat: add trimmed moop math header

---
 GL/sh4_math.h | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 GL/sh4_math.h

diff --git a/GL/sh4_math.h b/GL/sh4_math.h
new file mode 100644
index 0000000..97ea399
--- /dev/null
+++ b/GL/sh4_math.h
@@ -0,0 +1,54 @@
+// ---- sh4_math.h - SH7091 Math Module ----
+//
+// Version 1.0.8
+//
+// This file is part of the DreamHAL project, a hardware abstraction library
+// primarily intended for use on the SH7091 found in hardware such as the SEGA
+// Dreamcast game console.
+//
+// This math module is hereby released into the public domain in the hope that it
+// may prove useful. Now go hit 60 fps! :)
+//
+// --Moopthehedgehog
+//
+
+#pragma once
+
+// 1/x
+// (1.0f / sqrt(x)) ^ 2
+// This is about 3x faster than fdiv!
+static inline __attribute__((always_inline)) float MATH_Invert(float x)
+{
+  asm volatile ("fsrra %[one_div_sqrt]\n\t"
+  "fmul %[one_div_sqrt], %[one_div_sqrt]\n"
+  : [one_div_sqrt] "+f" (x) // outputs, "+" means r/w
+  : // no inputs
+  : // no clobbers
+  );
+
+  return x;
+}
+
+// 1/sqrt(x)
+static inline __attribute__((always_inline)) float MATH_fsrra(float x)
+{
+  asm volatile ("fsrra %[one_div_sqrt]\n"
+  : [one_div_sqrt] "+f" (x) // outputs, "+" means r/w
+  : // no inputs
+  : // no clobbers
+  );
+
+  return x;
+}
+
+// a*b+c
+static inline __attribute__((always_inline)) float MATH_fmac(float a, float b, float c)
+{
+  asm volatile ("fmac fr0, %[floatb], %[floatc]\n"
+    : [floatc] "+f" (c) // outputs, "+" means r/w
+    : "w" (a), [floatb] "f" (b) // inputs
+    : // no clobbers
+  );
+
+  return c;
+}
\ No newline at end of file