From f24b3987c0a4cf1d77455df50374e1b499f62f06 Mon Sep 17 00:00:00 2001
From: Richard Thier <magosit@outlook.hu>
Date: Sat, 18 Dec 2021 02:34:22 +0100
Subject: [PATCH] improved indirections

---
 magyarsort.h | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/magyarsort.h b/magyarsort.h
index 1ff572a..66d6aee 100644
--- a/magyarsort.h
+++ b/magyarsort.h
@@ -244,11 +244,9 @@ namespace MagyarSort {
 	struct RadixMagic : public RadixMagic<DIGIT - 1, COUNTER_TYP> {
 		inline __attribute__((always_inline)) RadixMagic(COUNTER_TYP *radics, uint32_t *from, uint32_t *to, COUNTER_TYP size) noexcept
 				: RadixMagic<DIGIT - 1, COUNTER_TYP>(radics, from, to, size) {
-					//
-			// Compile time - only happens on bottom level
-			if(DIGIT == 0) {
-				this->ourFrom = from;
-				this->ourTo = to;
+			// Tricky: see (**)
+			if(this->swapped) { // never true for DIGIT 0
+				std::swap(from, to);
 			}
 
 			// DEBUG
@@ -263,27 +261,26 @@ namespace MagyarSort {
 				if(i >= 64) { __builtin_prefetch(&from[i - 64]); } // TODO: manually unroll?
 				*/
 				// Get num and its new offset / location
-				auto num = this->ourFrom[i - 1];
+				auto num = from[i - 1];
 				auto digVal = getDigit<DIGIT>(num);
 				auto offset = (--rGet<DIGIT>(radics, digVal));
 
 				// Add to the proper target location
-				this->ourTo[offset] = num;
+				to[offset] = num;
 			}
 
 			// DEBUG
 			//printf("%d after: ", DIGIT);
 			//debugArr(to, size);
 
-			// Only swaps pointers :-)
-			std::swap(this->ourFrom, this->ourTo);
+			// (**) Only swaps pointers above in the child class constructor IF NEEDED :-)
+			this->swapped = !this->swapped;
 		}
 	};
 	/** Ends template recursion */
 	template<typename COUNTER_TYP>
 	struct RadixMagic<-1, COUNTER_TYP> {
-		uint32_t *ourFrom = nullptr;
-		uint32_t *ourTo = nullptr;
+		bool swapped = false;
 		inline RadixMagic(COUNTER_TYP *radics, uint32_t *&from, uint32_t *&to, COUNTER_TYP size) noexcept { }
 	};
 
@@ -370,8 +367,8 @@ namespace MagyarSort {
 		// With an other API we could spare this copy if we can delete original arr and return ptr or something...
 		// I am fine with this... this is not my main idea anyways, just little ILP tweak to regular radix sort
 		//if(to != arr) // <- logically, but bad they are already swapped here!!! BEWARE
-		if(r.ourFrom != arr) { // <- in reality this is what we want because of last swap happened anyways!
-			memcpy(arr, r.ourFrom, size);
+		if(r.swapped) { // <- in reality this is what we want because of last swap happened anyways!
+			memcpy(arr, to, size);
 		}
 	}