Update convert_Y_to_FAC1

STATUS.md

@@ -200,7 +200,7 @@ Floating point mathematical routines - not official, but well known and broadly
 | `$B1AA`   | `FACINX`               | NOT DONE | convert FAC1 to 16-bit signed integer              |
 | `$B1BF`   | `convert_FAC1_to_s16`  | NOT DONE |                                                    |
 | `$B391`   | `GIVAYF`               | PARTIAL  | not fully tested yet                               |
-| `$B3A2`   | `convert_Y_to_FAC1`    | DONE     |                                                    |
+| `$B3A2`   | `convert_Y_to_FAC1`    | DONE     | From the Microsoft BASIC, original name: SNGFLT    |
 | `$B794`   | `convert_u8_A_to_FAC1` | DONE     |                                                    |
 | `$B7B5`   | `STRVAL`               | PARTIAL  | Only for 38k memory model                          |
 | `$B7F7`   | `convert_FAC1_to_ADDR` | NOT DONE |                                                    |

src/basic/math/b3a2.convert_Y_to_FAC1.s

@@ -3,7 +3,9 @@
 ;; #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 - convert uint8 in Y to FAC1
 ;
 ; Input: Y - uint8 to convert to float
@@ -11,6 +13,8 @@
 ;
 ; Stores Y into first FAC1 mantissa byte, clears the second and calls convert_i16_to_FAC1
 ;
+; This is verified to be identical to the original Microsoft implementation where it was named SNGFLT.
+;
 ; - https://www.c64-wiki.com/wiki/BASIC-ROM
 ; - https://sta.c64.org/cbm64basconv.html
 ; - https://sourceforge.net/p/acme-crossass/code-0/38/tree/trunk/ACME_Lib/cbm/c64/float.a?force=True
@@ -18,7 +22,5 @@
 ;
 
 convert_Y_to_FAC1:
-    sty FAC1_mantissa+1
-    lda #$00
-    sta FAC1_mantissa
-    jmp convert_i16_to_FAC1
+    lda #0
+    beq GIVAYF      ; Always branches

tools/similarity.c

@@ -20,9 +20,10 @@ int matches[MAX_SIZE];
 
 int phase_mask[MAX_SIZE+MAX_SIZE];
 
-#define NUM_CHUNKS 6
+#define NUM_CHUNKS 7
 // Pairs of start, end memory addresses of known exact similarity with the open source Microsoft BASIC
 unsigned short microsoft_basic_chunks[NUM_CHUNKS * 2] = {
+    0xB3A2, 0xB3A5,
     0xB849, 0xB84F,
     0xB8D2, 0xB8D5,
     0xB947, 0xB97D,