From 0de507713b7c32f0514098f5458e493c22d69b23 Mon Sep 17 00:00:00 2001
From: Kawe Mazidjatari <48657826+Mauler125@users.noreply.github.com>
Date: Thu, 13 Jul 2023 00:06:56 +0200
Subject: [PATCH] Make fbits inline, and add PopCount

Floating point bitwise functions are now inline, also implemented a 'PopCount' function, which replicates the '__popcnt' instruction, but does not require the CPU to feature the instruction. This was mainly added as the SDK launcher doesn't check the CPU for SSSe3/popcnt, as it doesn't involve any instruction sets past SSE2.
---
 r5dev/mathlib/CMakeLists.txt |  2 +-
 r5dev/mathlib/bits.h         | 24 ++++++++++++++++
 r5dev/mathlib/fbits.cpp      | 45 -----------------------------
 r5dev/mathlib/fbits.h        | 56 ++++++++++++++++++++++++++++++------
 4 files changed, 72 insertions(+), 55 deletions(-)
 create mode 100644 r5dev/mathlib/bits.h
 delete mode 100644 r5dev/mathlib/fbits.cpp

diff --git a/r5dev/mathlib/CMakeLists.txt b/r5dev/mathlib/CMakeLists.txt
index 2095608d..8c638ed4 100644
--- a/r5dev/mathlib/CMakeLists.txt
+++ b/r5dev/mathlib/CMakeLists.txt
@@ -43,7 +43,7 @@ add_sources( SOURCE_GROUP "Vector"
 
 add_sources( SOURCE_GROUP "Math"
     "almostequal.cpp"
-    "fbits.cpp"
+    "bits.h"
     "fbits.h"
     "math_pfns.h"
     "mathlib.h"
diff --git a/r5dev/mathlib/bits.h b/r5dev/mathlib/bits.h
new file mode 100644
index 00000000..417dd471
--- /dev/null
+++ b/r5dev/mathlib/bits.h
@@ -0,0 +1,24 @@
+#ifndef MATHLIB_BITS_H
+#define MATHLIB_BITS_H
+//=============================================================================//
+//
+// Purpose: bitwise utilities.
+//
+//=============================================================================//
+
+//-----------------------------------------------------------------------------
+// '__popcnt' instruction reimplementation (allows for usage without requiring
+// a processor to feature the popcnt instruction, only use for tools that have
+// to run on processors that do NOT support popcnt!).
+//-----------------------------------------------------------------------------
+inline unsigned int PopCount(unsigned long long x)
+{
+    unsigned int count = 0;
+    while (x) {
+        x &= x - 1; // Clears the least significant bit set to 1.
+        count++;
+    }
+    return count;
+}
+
+#endif // MATHLIB_BITS_H
diff --git a/r5dev/mathlib/fbits.cpp b/r5dev/mathlib/fbits.cpp
deleted file mode 100644
index 2e7934ea..00000000
--- a/r5dev/mathlib/fbits.cpp
+++ /dev/null
@@ -1,45 +0,0 @@
-//=============================================================================//
-//
-// Purpose: look for NANs, infinities, and underflows.
-//
-//=============================================================================//
-
-#include "mathlib/fbits.h"
-
-//-----------------------------------------------------------------------------
-// This follows the ANSI/IEEE 754-1985 standard
-//-----------------------------------------------------------------------------
-unsigned long& FloatBits(float& f)
-{
-	return *reinterpret_cast<unsigned long*>(&f);
-}
-
-unsigned long const& FloatBits(float const& f)
-{
-	return *reinterpret_cast<unsigned long const*>(&f);
-}
-
-float BitsToFloat(unsigned long i)
-{
-	return *reinterpret_cast<float*>(&i);
-}
-
-bool IsFinite(float f)
-{
-	return ((FloatBits(f) & 0x7F800000) != 0x7F800000);
-}
-
-unsigned long FloatAbsBits(float f)
-{
-	return FloatBits(f) & 0x7FFFFFFF;
-}
-
-float FloatMakePositive(float f)
-{
-	return fabsf(f); // was since 2002: BitsToFloat( FloatBits(f) & 0x7FFFFFFF ); fixed in 2010
-}
-
-float FloatNegate(float f)
-{
-	return -f; //BitsToFloat( FloatBits(f) ^ 0x80000000 );
-}
diff --git a/r5dev/mathlib/fbits.h b/r5dev/mathlib/fbits.h
index eb0156c9..09968023 100644
--- a/r5dev/mathlib/fbits.h
+++ b/r5dev/mathlib/fbits.h
@@ -1,14 +1,52 @@
-#pragma once
+#ifndef MATHLIB_FBITS_H
+#define MATHLIB_FBITS_H
+//=============================================================================//
+//
+// Purpose: look for NANs, infinities, and underflows.
+//
+//=============================================================================//
 
-unsigned long& FloatBits(float& f);
-unsigned long const& FloatBits(float const& f);
-float BitsToFloat(unsigned long i);
-bool IsFinite(float f);
-unsigned long FloatAbsBits(float f);
-float FloatMakePositive(float f);
-float FloatNegate(float f);
+//-----------------------------------------------------------------------------
+// This follows the ANSI/IEEE 754-1985 standard
+//-----------------------------------------------------------------------------
+inline unsigned long& FloatBits(float& f)
+{
+	return *reinterpret_cast<unsigned long*>(&f);
+}
 
-#define FLOAT32_NAN_BITS     (std::uint32_t)0x7FC00000 // NaN!
+inline unsigned long const& FloatBits(float const& f)
+{
+	return *reinterpret_cast<unsigned long const*>(&f);
+}
+
+inline float BitsToFloat(unsigned long i)
+{
+	return *reinterpret_cast<float*>(&i);
+}
+
+inline bool IsFinite(float f)
+{
+	return ((FloatBits(f) & 0x7F800000) != 0x7F800000);
+}
+
+inline unsigned long FloatAbsBits(float f)
+{
+	return FloatBits(f) & 0x7FFFFFFF;
+}
+
+inline float FloatMakePositive(float f)
+{
+	return fabsf(f); // was since 2002: BitsToFloat( FloatBits(f) & 0x7FFFFFFF ); fixed in 2010
+}
+
+inline float FloatNegate(float f)
+{
+	return -f; //BitsToFloat( FloatBits(f) ^ 0x80000000 );
+}
+
+#define FLOAT32_NAN_BITS     (unsigned int)0x7FC00000 // NaN!
 #define FLOAT32_NAN          BitsToFloat( FLOAT32_NAN_BITS )
 
 #define VEC_T_NAN FLOAT32_NAN
+
+#endif // MATHLIB_FBITS_H