Update convert_A_to_FAC1

STATUS.md

@@ -236,7 +236,7 @@ Floating point mathematical routines - not official, but well known and broadly
 | `$BC1B`   | `round_FAC1`           | PARTIAL  | not fully tested yet                               |
 | `$BC2B`   | `sgn_FAC1_A`           | DONE     | From the Microsoft BASIC, original name: SIGN      |
 | `$BC39`   | `sgn_FAC1`             | DONE     | From the Microsoft BASIC, original name: SGN       |
-| `$BC3C`   | `convert_A_to_FAC1`    | DONE     |                                                    |
+| `$BC3C`   | `convert_A_to_FAC1`    | DONE     | From the Microsoft BASIC, original name: FLOAT     |
 | `$BC44`   | `convert_i16_to_FAC1`  | DONE     |                                                    |
 | `$BC58`   | `abs_FAC1`             | DONE     | From the Microsoft BASIC, original name: ABS       |
 | `$BC5B`   | `FCOMP`                | DONE     |                                                    |

src/basic/math/bc3c.convert_A_to_FAC1.s

@@ -3,22 +3,26 @@
 ;; #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 int8 in A to FAC1
 ;
 ; Input: A - int8 to convert to float
 ; Result: FAC1
 ;
+; This is verified to be identical to the original Microsoft implementation where it was named FLOAT.
+;
 ; Sets first byte of FAC1 to A, sign extends A into tge second byte and falls through to convert_i16_to_FAC1
 ;
 ; - https://codebase64.org/doku.php?id=base:asm_include_file_for_basic_routines
 ; - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
 ;
 
-
 convert_A_to_FAC1:
+    sta FAC1_mantissa+0
+    lda #0
     sta FAC1_mantissa+1
-    jsr sign_extend_A_to_Y
-    sty FAC1_mantissa
-    +nop                    ; To not leave a gap to the fallthrough
+    ldx #$88
+
     ; Fall through to convert_i16_to_FAC1

src/basic/math/sign_extend_A_to_Y.s

@@ -1,13 +0,0 @@
-;; #LAYOUT# STD *       #TAKE
-;; #LAYOUT# *   BASIC_0 #TAKE
-;; #LAYOUT# *   *       #IGNORE
-
-;
-; Math package - helper function to sign extend accumulator into Y
-
-sign_extend_A_to_Y:
-    cmp #$80                ; Copy sign into carry
-    ldy #$00                ; Y = $00
-    bcc @1                  ; Branch if not negative
-    dey                     ; Y = $FF
-@1: rts

tools/similarity.c

@@ -28,7 +28,7 @@ unsigned short microsoft_basic_chunks[NUM_CHUNKS * 2] = {
     0xB947, 0xB97D,
     0xB983, 0xB9BB,
     0xBBA2, 0xBC1A,
-    0xBC2B, 0xBC3B,
+    0xBC2B, 0xBC43,
     0xBC58, 0xBC5A,
     0xBC9B, 0xBCF2,
 };