Experimental code that turned out to be too slow and got scrapped.

docs/assembly_references.txt

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+EFLAGS bit meaning
+http://reverseengineering.stackexchange.com/a/9222
+
+GCC inline assembly
+http://ibiblio.org/gferg/ldp/GCC-Inline-Assembly-HOWTO.html
+
+Popping the FPU stack
+http://stackoverflow.com/a/33575875/768582
+
+Decoding a sample snippet of asm
+http://stackoverflow.com/questions/9186150/decoding-and-understanding-assembly-code
+
+GNU assembler examples
+http://cs.lmu.edu/~ray/notes/gasexamples/
+
+GCC function attributes (see "naked")
+https://gcc.gnu.org/onlinedocs/gcc-4.3.5/gcc/Function-Attributes.html
+
+Fast floating point sign
+http://stackoverflow.com/a/2508911/768582
+
+AMD assembly reference
+http://developer.amd.com/wordpress/media/2012/10/26569_APM_v51.pdf
+
+Moving values between SSE and FPU
+http://stackoverflow.com/questions/37567154/intel-x86-64-assembly-how-to-move-between-x87-and-sse2-calculating-arctangent#37573264

docs/old_code/asm/x86_64/fsgn.s

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+#
+#  Copyright 2016, 2017 Michele "King_DuckZ" Santullo
+
+#  This file is part of MyCurry.
+
+#  MyCurry is free software: you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation, either version 3 of the License, or
+#  (at your option) any later version.
+
+#  MyCurry is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+
+#  You should have received a copy of the GNU General Public License
+#  along with MyCurry.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+.data
+minus1: .float -1.0
+
+.global fsgn_asm
+
+.text
+fsgn_asm:
+	subq $24,%rsp
+	movss %xmm0,(%rsp)
+	fldz
+	flds (%rsp)
+	fcomp
+
+	fstsw %ax
+	sahf
+
+	fld1
+	fld minus1
+
+	fcmovnbe %st(1),%st
+	fcmove %st(2),%st
+
+	fstps (%rsp)
+	fninit
+	movss (%rsp),%xmm0
+
+	#xorpd %xmm0,%xmm0
+	addq $24,%rsp
+	ret

docs/old_code/fsgn_timing.cpp

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+/*
+	Copyright 2016, 2017 Michele "King_DuckZ" Santullo
+
+	This file is part of MyCurry.
+
+	MyCurry is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	MyCurry is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with MyCurry.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "fsgn_timing.hpp"
+#include "fsgn.hpp"
+#if defined(FSGN_WITH_TIMING)
+#	include <chrono>
+#	include <random>
+#	include <vector>
+#	include <algorithm>
+#	include <iostream>
+#endif
+
+namespace curry {
+#if defined(FSGN_WITH_TIMING)
+	void do_fsgn_timing() {
+		constexpr const auto count = 1000000U;
+		std::minstd_rand rand;
+		std::vector<float> inputs(count);
+		std::generate(inputs.begin(), inputs.end(), [&](){
+			return static_cast<float>(rand()) - static_cast<float>(rand.max()) / 2.0f;
+		});
+
+		//fast_fsgn
+		{
+			float result = 0.0f;
+
+			auto t_start = std::chrono::high_resolution_clock::now();
+			for (auto z = 0U; z < count; ++z) {
+				result += fast_fsgn(inputs[z]);
+			}
+			auto t_end = std::chrono::high_resolution_clock::now();
+
+			std::cout << "fast_fsgn result: " << result << " in " <<
+				std::chrono::duration<double>(t_end - t_start).count() << '\n';
+		}
+
+		//fsgn_asm
+		{
+			float result = 0.0f;
+
+			auto t_start = std::chrono::high_resolution_clock::now();
+			for (auto z = 0U; z < count; ++z) {
+				result += fsgn_asm(inputs[z]);
+			}
+			auto t_end = std::chrono::high_resolution_clock::now();
+
+			std::cout << "fsgn_asm result: " << result << " in " <<
+				std::chrono::duration<double>(t_end - t_start).count() << '\n';
+		}
+
+		//fsgn
+		{
+			float result = 0.0f;
+
+			auto t_start = std::chrono::high_resolution_clock::now();
+			for (auto z = 0U; z < count; ++z) {
+				result += fsgn(inputs[z]);
+			}
+			auto t_end = std::chrono::high_resolution_clock::now();
+
+			std::cout << "fsgn result: " << result << " in " <<
+				std::chrono::duration<double>(t_end - t_start).count() << '\n';
+		}
+	}
+#endif
+} //namespace curry

docs/old_code/fsgn_timing.hpp

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+/*
+	Copyright 2016, 2017 Michele "King_DuckZ" Santullo
+
+	This file is part of MyCurry.
+
+	MyCurry is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	MyCurry is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with MyCurry.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+#define FSGN_WITH_TIMING
+
+namespace curry {
+#if defined(FSGN_WITH_TIMING)
+	void do_fsgn_timing();
+#endif
+} //namespace curry