Update normal_FAC1

src/basic/math/b8d7.normal_FAC1.s

@@ -0,0 +1,41 @@
+;; #LAYOUT# STD *       #TAKE
+;; #LAYOUT# X16 BASIC_0 #TAKE-OFFSET 2000
+;; #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 - normalize FAC1
+;
+; This is verified to be identical to the original Microsoft implementation where it was named NORMAL.
+;
+; See also:
+; - [CM64] Computes Mapping the Commodore 64 - page 113
+; - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
+; - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
+;
+
+
+normal_FAC1:
+
+    ldy #0
+    tya
+    clc
+@1:
+    ldx FAC1_mantissa+0
+    bne NORM1
+    ldx FAC1_mantissa+1     ; Shift 8 bites at a time for speed
+    stx FAC1_mantissa
+    ldx FAC1_mantissa+2
+    stx FAC1_mantissa+1
+    ldx FAC1_mantissa+3
+    stx FAC1_mantissa+2
+    ldx FACOV
+    stx FAC1_mantissa+3
+    sty FACOV
+    adc #8
+    cmp #$20
+    bne @1
+
+    ; Fallthrough to zero_FAC1

src/basic/math/normal_FAC1.s

@@ -1,101 +0,0 @@
-;; #LAYOUT# STD *       #TAKE
-;; #LAYOUT# *   BASIC_0 #TAKE
-;; #LAYOUT# *   *       #IGNORE
-
-;
-; Math package - normalize FAC1
-;
-; See also:
-; - [CM64] Computes Mapping the Commodore 64 - page 113
-; - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
-; - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
-;
-
-; XXX test this
-
-normal_FAC1_impl:
-
-	lda FAC1_exponent
-	beq normal_FAC1_end                     ; branch if our float is 0
-	
-	; FALLTROUGH
-
-normal_FAC1_check_mantissa_byte:
-
-	lda FAC1_mantissa+0
-	beq normal_FAC1_by_byte                 ; branch if we can move the whole byte
-	
-	; FALLTROUGH
-
-normal_FAC1_check_mantissa_bit:
-
-	lda FAC1_mantissa+0                     ; XXX optimize for 65CE02?
-	and #$80
-	bne normal_FAC1_end                     ; branch if already normalized
-	
-	; FALLTROUGH
-	
-normal_FAC1_by_bit:
-	
-	; Decrement the exponent
-	
-	dec FAC1_exponent
-	beq normal_FAC1_end                     ; exponent reached 0, nothing more to do
-
-	; Multiply the mantissa by 2
-
-	asl FACOV
-	rol FAC1_mantissa+3
-	rol FAC1_mantissa+2
-	rol FAC1_mantissa+1
-	rol FAC1_mantissa+0
-	
-	bcc normal_FAC1_check_mantissa_bit      ; branch if next iteration needed
-	rts
-	
-normal_FAC1_by_byte:
-
-	; First decrement the exponent by 8, but not below 0
-	
-	lda FAC1_exponent
-	sec
-	sbc #$08
-	bcs @1
-	lda #$00
-@1:
-	sta FAC1_exponent
-	beq normal_FAC1_end                      ; branch if our float reached 0
-
-	; Now multiply the mantissa by 8 by moving the whole bytes
-	
-	lda FAC1_mantissa+1
-	sta FAC1_mantissa+0
-	lda FAC1_mantissa+2
-	sta FAC1_mantissa+1
-	lda FAC1_mantissa+3
-	sta FAC1_mantissa+2
-	
-	lda FACOV
-	sta FAC1_mantissa+3
-
-	lda #$00
-	sta FACOV
-	
-	; Now check if mantissa is not 0
-	
-	ora FAC1_mantissa+0
-	ora FAC1_mantissa+1
-	ora FAC1_mantissa+2
-	ora FAC1_mantissa+3
-	
-	bne normal_FAC1_check_mantissa_byte     ; not 0 - branch to next iteration
-
-	; Our mantissa reached 0 - mark exponent as 0 and finish
-	
-	sta FAC1_exponent
-
-	; FALLTROUGH
-
-normal_FAC1_end:
-
-	rts