Update add_FAC2_FAC1

STATUS.md

@@ -209,7 +209,7 @@ Floating point mathematical routines - not official, but well known and broadly
 | `$B853`   | `sub_FAC2_FAC1`        | DONE     | From the Microsoft BASIC, original name: FSUBT     |
 | `$B862`   | `add_align_exponents`  | DONE     | From the Microsoft BASIC, original name: FADD5     |
 | `$B867`   | `add_MEM_FAC1`         | DONE     | From the Microsoft BASIC, original name: FADD      |
-| `$B86A`   | `add_FAC2_FAC1`        | DONE     |                                                    |
+| `$B86A`   | `add_FAC2_FAC1`        | DONE     | From the Microsoft BASIC, original name: FADDT     |
 | `$B8D2`   | `abs_and_normal_FAC`   | DONE     | From the Microsoft BASIC, original name: FADFLT    |
 | `$B8D7`   | `normal_FAC1`          | DONE     | From the Microsoft BASIC, original name: NORMAL    |
 | `$B8F7`   | `zero_FAC1`            | DONE     | From the Microsoft BASIC, original name: ZEROFC    |

src/basic/math/add_FAC2_FAC1_sub.s

@@ -1,97 +0,0 @@
-;; #LAYOUT# STD *       #TAKE
-;; #LAYOUT# X16 BASIC_0 #TAKE-OFFSET 2000
-;; #LAYOUT# *   BASIC_0 #TAKE
-;; #LAYOUT# *   *       #IGNORE
-
-;
-; Math package - add FAC2 to FAC1, subtraction part
-;
-
-; XXX test this
-
-add_FAC2_FAC1_sub:
-
-	; First verify that |FAC1| > |FAC2|, branch to proper variant if it is not
-	; We ignore FACOV here. Note, that exponents are already equalized
-
-	lda FAC1_mantissa+0
-	cmp FAC2_mantissa+0
-	bcc add_FAC2_FAC1_sub_rev          ; if FAC1 < FAC2, branch
-	bne @1                             ; if FAC1 > FAC2, branch
-
-	lda FAC1_mantissa+1
-	cmp FAC2_mantissa+1
-	bcc add_FAC2_FAC1_sub_rev          ; if FAC1 < FAC2, branch
-	bne @1                             ; if FAC1 > FAC2, branch
-
-	lda FAC1_mantissa+2
-	cmp FAC2_mantissa+2
-	bcc add_FAC2_FAC1_sub_rev          ; if FAC1 < FAC2, branch
-	bne @1                             ; if FAC1 > FAC2, branch
-
-	lda FAC1_mantissa+3
-	cmp FAC2_mantissa+3
-	bcc add_FAC2_FAC1_sub_rev          ; if FAC1 < FAC2, branch
-	bne @1                             ; if FAC1 > FAC2, branch
-
-	; If we are here, than FAC1 is equal to FAC2 - so just set FAC1 to 0
-	
-	lda #$00
-	sta FAC1_exponent
-	rts
-@1:
-	; Perform the subtration, FAC1 = FAC1 - FAC2
-
-	sec
-	lda FAC1_mantissa+3
-	sbc FAC2_mantissa+3
-	sta FAC1_mantissa+3
-
-	lda FAC1_mantissa+2
-	sbc FAC2_mantissa+2
-	sta FAC1_mantissa+2
-	
-	lda FAC1_mantissa+1
-	sbc FAC2_mantissa+1
-	sta FAC1_mantissa+1	
-
-	lda FAC1_mantissa+0
-	sbc FAC2_mantissa+0
-	sta FAC1_mantissa+0	
-	
-	; Exponent should never need adaptation here
-	
-	jmp normal_FAC1
-
-add_FAC2_FAC1_sub_rev:
-
-	; Since |FAC1| < |FAC2|, toggle FAC1 sign before subtraction
-
-	jsr toggle_sign_FAC1_skipcheck
-
-	; Perform the subtration, FAC1 = FAC2 - FAC1
-	
-	sec
-	lda #$00
-	sbc FACOV
-	sta FACOV
-	
-	lda FAC2_mantissa+3
-	sbc FAC1_mantissa+3
-	sta FAC1_mantissa+3
-
-	lda FAC2_mantissa+2
-	sbc FAC1_mantissa+2
-	sta FAC1_mantissa+2
-	
-	lda FAC2_mantissa+1
-	sbc FAC1_mantissa+1
-	sta FAC1_mantissa+1	
-
-	lda FAC2_mantissa+0
-	sbc FAC1_mantissa+0
-	sta FAC1_mantissa+0
-	
-	; Exponent should never need adaptation here
-
-	jmp normal_FAC1

src/basic/math/b86a.add_FAC2_FAC1.s

@@ -3,14 +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 - add FAC2 to FAC1
 ;
 ; Input:
 ; - .A - must load FAC1 exponent ($61) beforehand to set the zero flag
 ;
-; Note:
+; This is verified to be identical to the original Microsoft implementation where it was named FADDT.
-; - load FAC2 after FAC1, or mimic the Kernals sign comparison (XXX do we need it?)
+;
 ;
 ; See also:
 ; - [CM64] Computes Mapping the Commodore 64 - page 112
@@ -18,79 +20,65 @@
 ; - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
 ;
 
-; XXX test this
-
 add_FAC2_FAC1:
 
-	; Check if FAC2 is 0; if so leave FAC1 without changes
+    bne @1              ; If FAC1=0 result is in FAC2
+    jmp mov_FAC2_FAC1
+@1:
+    ldx FACOV
+    stx OLDOV
+    ldx #FAC2_exponent
+    lda FAC2_exponent
+FADDC:
+    tay
+    beq FADDC;ZERRTS
+    sec
+    sbc FAC1_exponent
+    beq FADD4           ; No shifting
+    bcc @1              ; Branch if FAC2_exponent < FAC1_exponent
+    sty FAC1_exponent   ; Resulting exponent
+    ldy FAC2_sign       ; Since FAC2 is larger, its
+    sty FAC1_sign       ; sign is sign of result
+    eor #$FF            ; Shift a negative number of places
+    adc #0              ; Complete negation  C=1
+    ldy #0
+    sty OLDOV
+    ldx #FAC1_exponent
+    bne @2
+@1:
+    ldy #0
+    sty FACOV
+@2:
+    cmp #$F9
+    bmi add_align_exponents
+    tay
+    lda FACOV
+    lsr 1,X
+    jsr short_shift_FAC
+FADD4:
+    bit ARISGN
+    bpl add_mantissas_FAC2_FAC1
+    ldy #FAC1_exponent
+    cpx #FAC2_exponent      ; FAC1 is bigger
+    beq @1
+    ldy #FAC2_exponent      ; FAC2 is bigger
+@1:
+    sec
+    eor #$FF
+    adc OLDOV
+    sta FACOV
+    lda 4,Y
+    sbc 4,X
+    sta FAC1_mantissa+3
+    lda 3,Y
+    sbc 3,X
+    sta FAC1_mantissa+2
+    lda 2,Y
+    sbc 2,X
+    sta FAC1_mantissa+1
+    lda 1,Y
+    sbc 1,X
+    sta FAC1_mantissa+0    
 
-	lda FAC2_exponent
+    ; Fallthrough to abs_and_normalize_FAC1
-	beq add_FAC2_FAC1_done
 
-	; If FAC1 is 0, if so just copy FAC2 to FAC1
-
-	lda FAC1_exponent
-	+beq mov_FAC2_FAC1
-
-	; Make sure the exponents are aligned
-
-	jsr add_align_exponents
-
-	; Check whether signs are the same
-
-	lda FAC1_sign
-	eor FAC2_sign
-
-	+bmi add_FAC2_FAC1_sub           ; branch if signs are opposite
-
-	; Perform the addition
-	
-	clc
-	lda FAC2_mantissa+3
-	adc FAC1_mantissa+3
-	sta FAC1_mantissa+3
-
-	lda FAC2_mantissa+2
-	adc FAC1_mantissa+2
-	sta FAC1_mantissa+2
-	
-	lda FAC2_mantissa+1
-	adc FAC1_mantissa+1
-	sta FAC1_mantissa+1	
-
-	lda FAC2_mantissa+0
-	adc FAC1_mantissa+0
-	sta FAC1_mantissa+0	
-	
-	+bcc normal_FAC1                 ; end if no need to adapt the exponent
-
-	inc FAC1_exponent
-	bne add_FAC2_FAC1_adapt_mantissa   ; end if no overflow
-	
-	; FALLTROUGH
-
-set_FAC1_max:                          ; entry used by other routines too
-
-	lda #$FF
-	sta FAC1_exponent
-	sta FAC1_mantissa+3
-	sta FAC1_mantissa+2
-	sta FAC1_mantissa+1
-	sta FAC1_mantissa+0	
-
-	; FALLTROUGH
-
-add_FAC2_FAC1_done:
-
-	rts
-
-add_FAC2_FAC1_adapt_mantissa:
-
-	sec
-	ror FAC1_mantissa+0
-	ror FAC1_mantissa+1
-	ror FAC1_mantissa+2
-	ror FAC1_mantissa+3
-	ror FACOV
-	
-	rts

tools/similarity.c

@@ -20,13 +20,12 @@ int matches[MAX_SIZE];
 
 int phase_mask[MAX_SIZE+MAX_SIZE];
 
-#define NUM_CHUNKS 8
+#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] = {
     0xB391, 0xB39D,
     0xB3A2, 0xB3A5,
-    0xB849, 0xB869,
+    0xB849, 0xB97D,
-    0xB8D2, 0xB97D,
     0xB983, 0xB9BB,
     0xBA8C, 0xBAB6,
     0xBBA2, 0xBC1A,