From 256a976a1a6fbc402e6d0fcd47fd4abc4a525fe0 Mon Sep 17 00:00:00 2001
From: Rikard Nordgren <hrn@posteo.net>
Date: Wed, 1 Apr 2026 21:26:57 +0200
Subject: [PATCH] Update div10

---
 STATUS.md                          |  2 +-
 src/basic/math/bafe.div10_FAC1_p.s | 19 ++++++++++++-------
 tools/similarity.c                 |  2 +-
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/STATUS.md b/STATUS.md
index 2b398dc9..a152359b 100644
--- a/STATUS.md
+++ b/STATUS.md
@@ -224,7 +224,7 @@ Floating point mathematical routines - not official, but well known and broadly
 | `$BA8C`   | `mov_MEM_FAC2`         | DONE     | From the Microsoft BASIC, original name: CONUPK    |
 | `$BA90`   | `get_FAC2_via_INDEX`   | DONE     | From the Microsoft BASIC, no label                 |
 | `$BAE2`   | `mul10_FAC1`           | DONE     | From the Microsoft BASIC, original name: MUL10     |
-| `$BAFE`   | `div10_FAC1_p`         | DONE     |                                                    |
+| `$BAFE`   | `div10_FAC1_p`         | DONE     | From the Microsoft BASIC, original name: DIV10     |
 | `$BB0F`   | `div_MEM_FAC1`         | DONE     |                                                    |
 | `$BB12`   | `div_FAC2_FAC1`        | DONE     |                                                    |
 | `$BB8F`   | `mov_RES_FAC1`         | DONE     | From the Microsoft BASIC, original name: MOVFR     |
diff --git a/src/basic/math/bafe.div10_FAC1_p.s b/src/basic/math/bafe.div10_FAC1_p.s
index 4a83d10f..6dee63d3 100644
--- a/src/basic/math/bafe.div10_FAC1_p.s
+++ b/src/basic/math/bafe.div10_FAC1_p.s
@@ -3,11 +3,16 @@
 ;; #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 - divide FAC1 by 10, result is always positive
 ;
+;
+; This is verified to be identical to the original Microsoft implementation where it was named DIV10.
+;
 ; Notes:
-; - moves FAC1 to FAC2, loads FAC1 with the constant 10, jumps to the division routine
+; - moves FAC1 to FAC2, loads FAC1 with the constant 10, falls through to the division routine
 
 ;
 ; See also:
@@ -18,9 +23,9 @@
 
 div10_FAC1_p:
 
-    jsr mov_FAC1_FAC2
-    ldy #>const_TEN
-    lda #<const_TEN
-    jsr mov_MEM_FAC1
+    	jsr	mov_r_FAC1_FAC2
+        lda #<const_TEN
+        ldy #>const_TEN
+	    ldx #0      		    ; SIGNS ARE BOTH POSITIVE.
 
-    jmp div_FAC2_FAC1
+        ; Fallthrough to div_FAC2_MEM
diff --git a/tools/similarity.c b/tools/similarity.c
index d0c89ff1..29a88c97 100644
--- a/tools/similarity.c
+++ b/tools/similarity.c
@@ -27,7 +27,7 @@ unsigned short microsoft_basic_chunks[NUM_CHUNKS * 2] = {
     0xB3A2, 0xB3A5,
     0xB849, 0xB97D,
     0xB983, 0xB9BB,
-    0xBA28, 0xBAFD,
+    0xBA28, 0xBB06,
     0xBB8F, 0xBCF2,
 };