Update MUL10

src/basic/math/bae2.mul10_FAC1.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 - multiply FAC1 by 10
 ;
+; This is verified to be identical to the original Microsoft implementation where it was named MUL10
+;
 ; See also:
 ; - [CM64] Computes Mapping the Commodore 64 - page 114
 ; - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
@@ -14,28 +18,17 @@
 
 mul10_FAC1:
 
-	; Handle special case of FAC1 equal 0
+MUL10:	
 
-	lda FAC1_exponent
-	beq mul10_FAC1_done
-
-	; Start by multiplying FAC1 by 2
-
-	jsr mul10_FAC1_mul2
-
-	; Move FAC1 to FAC2, so that FAC1 = FAC2 = 2 * initial
-
-	jsr mov_FAC1_FAC2
-
-	; Multiply FAC1 by 4
-
-	jsr mul10_FAC1_mul2
-	jsr mul10_FAC1_mul2
-
-	; Now we have FAC1 = 8 * initial and FAC2 = 2 * initial; so just add these 2 values
-
-	jmp add_FAC2_FAC1
-
-mul10_FAC1_done:
-
-	rts
+        jsr mov_r_FAC1_FAC2
+        tax
+        beq MUL10R
+        clc
+        adc #2
+        bcs GOOVER      ; Closest jmp to overflow
+FINML6: ldx #0
+        stx ARISGN
+        jsr FADDC
+        inc FAC1_exponent
+        beq GOOVER
+MUL10R: rts