From 757b73238e00e4a0ccacb889e268d2fd0e35d030 Mon Sep 17 00:00:00 2001
From: Vitor Fernandes <vitor.fernandes@jumo.world>
Date: Thu, 16 Jul 2020 01:20:12 +0100
Subject: [PATCH] Fix msb2

---
 src/bmath/demos/math.cpp |  5 +++--
 src/bmath/math.cpp       | 11 +++++++++--
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/bmath/demos/math.cpp b/src/bmath/demos/math.cpp
index f593012..77c2e62 100644
--- a/src/bmath/demos/math.cpp
+++ b/src/bmath/demos/math.cpp
@@ -8,10 +8,11 @@ int main(void)
   Int a = -12;
   Float b = -12.0f;
 
-  Int c=3;
+  Int c=-3;
   Int d=4;
 
   std::cout << "A: " << a << ", abs(A): " << Math<Int>::abs(a) << std::endl;
   std::cout << "B: " << b << ", abs(B): " << Math<Float>::abs(b) << std::endl;
-  std::cout << "MAX(C,D)=(" << c << ", " << d << "), max(C,D): " << Math<Int>::max(c,d) << std::endl;
+  std::cout << "MAX(C,D)=(" << c << ", " << d << "), max(C,D): " << Math<Int>::max(d,c) << std::endl;
+  std::cout << "MIN(C,D)=(" << c << ", " << d << "), min(C,D): " << Math<Int>::min(c,d) << std::endl;
 }
diff --git a/src/bmath/math.cpp b/src/bmath/math.cpp
index e389d62..f4afbee 100644
--- a/src/bmath/math.cpp
+++ b/src/bmath/math.cpp
@@ -1,6 +1,7 @@
 #include "math.hpp"
 
 //http://graphics.stanford.edu/~seander/bithacks.html
+//https://hbfs.wordpress.com/2008/08/05/branchless-equivalents-of-simple-functions/
 //access CHAR_BIT --> const with number of bits in a byte (usually 8)
 #include <limits.h>
 #include <iostream>
@@ -32,7 +33,7 @@ inline Int msb2(Int value)
   } SInt;
 
   SInt sint = {.sint = value};
-  return sint.sint;
+  return sint.int_with_msb.signal;
 };
 
 /**
@@ -50,8 +51,14 @@ Float BMath::Math<Float>::abs(Float value)
   return value > 0 ? value : -value;
 };
 
+template <>
+Int BMath::Math<Int>::min(Int a,Int b)
+{
+  return b + ((a-b) & msb2(a-b));
+}
+
 template <>
 Int BMath::Math<Int>::max(Int a,Int b)
 {
-  return (a-b) & msb2(a-b);
+  return a + ((b-a) & ~msb2(b-a));
 }