From 24f1bc919398c34614a1b2f52d8f68c9796e4ea0 Mon Sep 17 00:00:00 2001
From: Rikard Nordgren <hrn@posteo.net>
Date: Wed, 15 Apr 2026 18:48:55 +0200
Subject: [PATCH] Add sqr_FAC2

---
 STATUS.md                                     |  2 +-
 .../{,stubs_math => math_trans}/bf74.interop  |  0
 .../bf74.sqr_FAC2.s                           | 19 ++++++++++++++++---
 tools/similarity.c                            |  2 +-
 4 files changed, 18 insertions(+), 5 deletions(-)
 rename src/basic/{,stubs_math => math_trans}/bf74.interop (100%)
 rename src/basic/{,stubs_math => math_trans}/bf74.sqr_FAC2.s (54%)

diff --git a/STATUS.md b/STATUS.md
index f40beb54..e8d1a783 100644
--- a/STATUS.md
+++ b/STATUS.md
@@ -252,7 +252,7 @@ Floating point mathematical routines - not official, but well known and broadly
 | `$BD7E`   | `FINLOG`               | DONE     | From the Microsoft BASIC, original name: FINLOG    |
 | `$BDDD`   | `FOUT`                 | DONE     | From the Microsoft BASIC, original name: FOUT      |
 | `$BF71`   | `sqr_FAC1`             | DONE     | From the Microsoft BASIC, original name: SQR       |
-| `$BF74`   | `sqr_FAC2`             | NOT DONE |                                                    |
+| `$BF74`   | `sqr_FAC2`             | DONE     | From the Microsoft BASIC, no label                 |
 | `$BF78`   | `pwr_FAC2_MEM`         | PARTIAL  | needs `pwr_FAC2_FAC1`                              |
 | `$BF7B`   | `pwr_FAC2_FAC1`        | NOT DONE |                                                    |
 | `$BFB4`   | `toggle_sign_FAC1`     | DONE     | From the Microsoft BASIC, original name: NEGOP     |
diff --git a/src/basic/,stubs_math/bf74.interop b/src/basic/math_trans/bf74.interop
similarity index 100%
rename from src/basic/,stubs_math/bf74.interop
rename to src/basic/math_trans/bf74.interop
diff --git a/src/basic/,stubs_math/bf74.sqr_FAC2.s b/src/basic/math_trans/bf74.sqr_FAC2.s
similarity index 54%
rename from src/basic/,stubs_math/bf74.sqr_FAC2.s
rename to src/basic/math_trans/bf74.sqr_FAC2.s
index 1cb3db61..c6d48c49 100644
--- a/src/basic/,stubs_math/bf74.sqr_FAC2.s
+++ b/src/basic/math_trans/bf74.sqr_FAC2.s
@@ -3,9 +3,13 @@
 ;; #LAYOUT# *   BASIC_0 #TAKE
 ;; #LAYOUT# *   *       #IGNORE
 
-;
+; This file is under the MIT license, it contains code released by Microsoft Corporation.
+; See LICENSE for more information.
+
 ; Math package - square root of FAC2
 ;
+; This is verified to be identical to the original Microsoft implementation where it was unnamed
+;
 ; Note:
 ; - loads .5 into FAC1 and falling through to the exponentiation routine
 ;
@@ -15,8 +19,17 @@
 ; - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
 ;
 
-; XXX provide implementation
+!ifdef CONFIG_TRANSCENDENTAL_FUNCTIONS {
+
 
 sqr_FAC2:
 
-	+STUB_IMPLEMENTATION
+        lda #<const_HALF
+        ldy #>const_HALF
+
+        ; FALLLTROUGH to pwr_FAC2_MEM
+
+
+} else {
+    jmp do_NOT_IMPLEMENTED_error
+}
diff --git a/tools/similarity.c b/tools/similarity.c
index 15cb5bc3..ec251c1c 100644
--- a/tools/similarity.c
+++ b/tools/similarity.c
@@ -31,7 +31,7 @@ unsigned short microsoft_basic_chunks[NUM_CHUNKS * 2] = {
     0xBD7E, 0xBD90,
     0xBDB3, 0xBDC1,
     0xBDDD, 0xBF51,
-    0xBF71, 0xBF73,
+    0xBF71, 0xBF77,
     0xBFB4, 0xBFEC,
     0xE043, 0xE08C,
     0xE264, 0xE2C2,     // Two byte gap here is an optimization