Improved checkbits calculation in for-loops

Author: Forceflow

include/libmorton/morton3D.h

@@ -12,7 +12,6 @@
 #define EIGHTBITMASK (morton) 0x000000FF
 #define NINEBITMASK (morton) 0x000001FF
 
-
 namespace libmorton {
 	// AVAILABLE METHODS FOR ENCODING
 	template<typename morton, typename coord> inline morton m3D_e_sLUT(const coord x, const coord y, const coord z);
@@ -126,7 +125,7 @@ namespace libmorton {
 	template<typename morton, typename coord>
 	inline morton m3D_e_for(const coord x, const coord y, const coord z) {
 		morton answer = 0;
-		unsigned int checkbits = static_cast<unsigned int>(floor((sizeof(morton) * 8.0f / 3.0f)));
+		unsigned int checkbits = (sizeof(morton) * 8) / 3;
 		for (unsigned int i = 0; i < checkbits; ++i) {
 			morton mshifted = static_cast<morton>(1) << i; // Here we need to cast 0x1 to 64bits, otherwise there is a bug when morton code is larger than 32 bits
 			unsigned int shift = 2 * i; // because you have to shift back i and forth 3*i
@@ -143,7 +142,7 @@ namespace libmorton {
 	inline morton m3D_e_for_ET(const coord x, const coord y, const coord z) {
 		morton answer = 0;
 		unsigned long x_max = 0, y_max = 0, z_max = 0;
-		unsigned int checkbits = static_cast<unsigned int>(floor((sizeof(morton) * 8.0f / 3.0f)));
+		unsigned int checkbits = (sizeof(morton) * 8) / 3;
 		findFirstSetBit<morton>(x, &x_max);
 		findFirstSetBit<morton>(y, &y_max);
 		findFirstSetBit<morton>(z, &z_max);
@@ -158,13 +157,12 @@ namespace libmorton {
 		return answer;
 	}
 
-
 	// HELPER METHOD for LUT decoding
 	// todo: wouldn't this be better with 8-bit aligned decode LUT?
 	template<typename morton, typename coord>
 	inline coord morton3D_DecodeCoord_LUT256(const morton m, const uint_fast8_t *LUT, const unsigned int startshift) {
 		morton a = 0;
-		unsigned int loops = (sizeof(morton) <= 4) ? 4 : 7; // ceil for 32bit, floor for 64bit
+		unsigned int loops = (sizeof(morton) <= 4) ? 4 : 7;
 		for (unsigned int i = 0; i < loops; ++i) {
 			a |= (morton)(LUT[(m >> ((i * 9) + startshift)) & NINEBITMASK] << morton(3 * i));
 		}
@@ -254,7 +252,7 @@ namespace libmorton {
 	template<typename morton, typename coord>
 	inline void m3D_d_for(const morton m, coord& x, coord& y, coord& z) {
 		x = 0; y = 0; z = 0;
-		unsigned int checkbits = static_cast<unsigned int>(floor((sizeof(morton) * 8.0f / 3.0f)));
+		unsigned int checkbits = (sizeof(morton) * 8) / 3;
 		for (unsigned int i = 0; i <= checkbits; ++i) {
 			morton selector = 1;
 			unsigned int shift_selector = 3 * i;
@@ -271,8 +269,8 @@ namespace libmorton {
 		x = 0; y = 0; z = 0;
 		unsigned long firstbit_location = 0;
 		if (!findFirstSetBit<morton>(m, &firstbit_location)) return;
-		float defaultbits = floor((sizeof(morton) * 8.0f / 3.0f));
-		unsigned int checkbits = static_cast<unsigned int>(std::min(defaultbits, firstbit_location / 3.0f));
+		unsigned int defaultbits = (sizeof(morton) * 8) / 3;
+		unsigned int checkbits = static_cast<unsigned int>(std::min((float) defaultbits, firstbit_location / 3.0f));
 		for (unsigned int i = 0; i <= checkbits; ++i) {
 			morton selector = 1;
 			unsigned int shift_selector = 3 * i;
@@ -282,4 +280,4 @@ namespace libmorton {
 			z |= (m & (selector << (shift_selector + 2))) >> (shiftback + 2);
 		}
 	}
-}
+}