From 826f0ac039cdb0e6641972b7cdf29553b4395b92 Mon Sep 17 00:00:00 2001
From: wheremyfoodat <44909372+wheremyfoodat@users.noreply.github.com>
Date: Sun, 16 Jul 2023 19:23:42 +0300
Subject: [PATCH] Fix up comments and readme

---
 readme.md                                         | 1 +
 src/core/PICA/dynapica/shader_rec_emitter_x64.cpp | 8 +++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/readme.md b/readme.md
index 9c98178d..854267b6 100644
--- a/readme.md
+++ b/readme.md
@@ -83,6 +83,7 @@ Panda3DS also supports controller input using the SDL2 GameController API.
 - [Corgi3DS](https://github.com/PSI-Rockin/Corgi3DS), an LLE 3DS emulator which both served as an inspiration, as well as a nice source of documentation for some PICA200-related things
 
 # Sister Projects
+- [Dynarmic](https://github.com/merryhime/dynarmic): An arm32/arm64 to x86-64/ARMv8 recompiler
 - [PCSX-Redux](https://github.com/grumpycoders/pcsx-redux): A PlayStation 1 emulator targetting developers, reverse engineers and regular PS1 fans alike
 - [SkyEmu](https://github.com/skylersaleh/SkyEmu): A seagull-themed low-level GameBoy, GameBoy Color, GameBoy Advance and Nintendo DS emulator that is designed to be easy to use, cross platform and accurate.
 - [NanoBoyAdvance](https://github.com/nba-emu/NanoBoyAdvance): A Game Boy Advance emulator focusing on hardware research and cycle-accurate emulation
diff --git a/src/core/PICA/dynapica/shader_rec_emitter_x64.cpp b/src/core/PICA/dynapica/shader_rec_emitter_x64.cpp
index 7f4eb00c..13eb630e 100644
--- a/src/core/PICA/dynapica/shader_rec_emitter_x64.cpp
+++ b/src/core/PICA/dynapica/shader_rec_emitter_x64.cpp
@@ -945,14 +945,19 @@ void ShaderEmitter::printLog(const PICAShader& shaderUnit) {
 Xbyak::Label ShaderEmitter::emitLog2Func() {
 	Xbyak::Label subroutine;
 
+	// This code uses the fact that log2(float) = log2(2^exponent * mantissa)
+	// = log2(2^exponent) + log2(mantissa) = exponent + log2(mantissa) where mantissa has a limited range of values
+	// https://stackoverflow.com/a/45787548
+
 	// SSE does not have a log instruction, thus we must approximate.
-	// We perform this approximation first performaing a range reduction into the range [1.0, 2.0).
+	// We perform this approximation first performing a range reduction into the range [1.0, 2.0).
 	// A minimax polynomial which was fit for the function log2(x) / (x - 1) is then evaluated.
 	// We multiply the result by (x - 1) then restore the result into the appropriate range.
 
 	// Coefficients for the minimax polynomial.
 	// f(x) computes approximately log2(x) / (x - 1).
 	// f(x) = c4 + x * (c3 + x * (c2 + x * (c1 + x * c0)).
+	// We align the table of coefficients to 64 bytes, so that the whole thing will fit in 1 cache line
 	align(64);
 	const void* c0 = getCurr();
 	dd(0x3d74552f);
@@ -1055,6 +1060,7 @@ Xbyak::Label ShaderEmitter::emitExp2Func() {
 	// A minimax polynomial which was fit for the function exp2(x) is then evaluated.
 	// We then restore the result into the appropriate range.
 
+	// Similarly to log2, we align our literal pool to 64 bytes to make sure the whole thing fits in 1 cache line
 	align(64);
 	const void* input_max = getCurr();
 	dd(0x43010000);