From f1d2f8d53d08943ec39bfe21c4c51ec3973e0dae Mon Sep 17 00:00:00 2001
From: FeralChild64 <you@example.com>
Date: Fri, 28 Feb 2020 20:04:02 +0100
Subject: [PATCH] added polynomial for sine approximation

---
 STATUS.md                             |  2 +-
 c64/basic/,stubs_math/e26b.sin_FAC1.s | 11 +++++++++++
 tools/generate_constants.cc           | 10 ++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/STATUS.md b/STATUS.md
index b568ba51..ad5d7e75 100644
--- a/STATUS.md
+++ b/STATUS.md
@@ -239,7 +239,7 @@ Floating point mathematical routines - not official, but well known and broadly
 | `$E09A`   | `rnd_A`                | DONE     |                                                    |
 | `$E0BE`   | `rnd_generate`         | DONE     |                                                    |
 | `$E264`   | `cos_FAC1`             | NOT DONE |                                                    |
-| `$E26B`   | `sin_FAC1`             | NOT DONE |                                                    |
+| `$E26B`   | `sin_FAC1`             | NOT DONE | some work already started                          |
 | `$E2B4`   | `tan_FAC1`             | NOT DONE |                                                    |
 | `$E30E`   | `atn_FAC1`             | NOT DONE |                                                    |
 
diff --git a/c64/basic/,stubs_math/e26b.sin_FAC1.s b/c64/basic/,stubs_math/e26b.sin_FAC1.s
index 99eb4569..82a86d2f 100644
--- a/c64/basic/,stubs_math/e26b.sin_FAC1.s
+++ b/c64/basic/,stubs_math/e26b.sin_FAC1.s
@@ -15,3 +15,14 @@
 
 sin_FAC1:
 	STUB_IMPLEMENTATION()
+
+poly_sin:
+
+	.byte $05                          // series length - 1
+
+	put_const_POLY_SIN_1()
+	put_const_POLY_SIN_2()
+	put_const_POLY_SIN_3()
+	put_const_POLY_SIN_4()
+	put_const_POLY_SIN_5()
+	put_const_POLY_SIN_6()
diff --git a/tools/generate_constants.cc b/tools/generate_constants.cc
index 6d27caed..5e40b233 100644
--- a/tools/generate_constants.cc
+++ b/tools/generate_constants.cc
@@ -57,6 +57,16 @@ std::vector<ConstEntry> GLOBAL_constants =
 	ConstEntry( "INV_SQR_2", 1.0 / std::sqrt(2.0) ),
 	ConstEntry(     "LOG_2", std::log(2.0)        ),
 	ConstEntry( "INV_LOG_2", 1.0 / std::log(2.0)  ),
+
+	// Constants for sine approximation, minimized abs. error, degree 11, from:
+	// - https://publik-void.github.io/sin-cos-approximations/
+
+	ConstEntry( "POLY_SIN_1", -2.3794713545277060334805162803882547e-8   ),
+	ConstEntry( "POLY_SIN_2",  2.75188556386854406868696924998396177e-6  ),
+	ConstEntry( "POLY_SIN_3", -0.000198407028626057951892931706291369095 ),
+	ConstEntry( "POLY_SIN_4",  0.00833332926445715285723741015926085083  ),
+	ConstEntry( "POLY_SIN_5", -0.166666665414391662957238076832950332    ),
+	ConstEntry( "POLY_SIN_6",  0.99999999988985190065414932682350994     ),
 };
 
 //