tfv: use the re-arranged multiply register results to optimize

cycle count actually gets worse, but that was due to a bug in
the cycle counting missing two of the add routines

gr-sim/tfv_flying_6502.c

@@ -756,11 +756,12 @@ static void draw_background_mode7(void) {
 		fixed_mul(ram[SPACEX_I],ram[SPACEX_F],
 			ram[TEMP_I],ram[TEMP_F],
 			&ram[SPACEX_I],&ram[SPACEX_F],0);
-							cycles.mode7+=26;
+							cycles.mode7+=20;
 
 		fixed_add(ram[SPACEX_I],ram[SPACEX_F],
 			ram[CX_I],ram[CX_F],
 			&ram[SPACEX_I],&ram[SPACEX_F]);
+							cycles.mode7+=16;
 
 
 		ram[TEMP_I]=fixed_sin[ram[ANGLE]&0xf].i;
@@ -770,11 +771,12 @@ static void draw_background_mode7(void) {
 		fixed_mul(ram[SPACEY_I],ram[SPACEY_F],
 			ram[TEMP_I],ram[TEMP_F],
 			&ram[SPACEY_I],&ram[SPACEY_F],0);
-							cycles.mode7+=26;
+							cycles.mode7+=20;
 
 		fixed_add(ram[SPACEY_I],ram[SPACEY_F],
 			ram[CY_I],ram[CY_F],
 			&ram[SPACEY_I],&ram[SPACEY_F]);
+							cycles.mode7+=16;
 
 
 // mul7

tfv/OPTIMIZATION

@@ -210,6 +210,21 @@ Move spacez updates out of line and also do some self modifying code
 	Total =                 181,077
 	Frame Rate = 5.52 fps
 
+Re-arranged multiply result register to allow more optimization.
+This looks like a pessimization, but it's because the cycle counting code
+	had been undercounting and missed a few add routines :(
+
+	Cycles: flying=             187
+	Cycles: getkey=              46
+	Cycles: page_flip=           26
+	Cycles: multiply=        40,680
+	Cycles: mode7=          115,470
+	Cycles: lookup_map=      22,747
+	Cycles: put_sprite=       2,561
+	================================
+	Total =                 181,717
+	Frame Rate = 5.50 fps
+
 
 Each cycle removed from inner X loop saves
 	32*40=1280 cycles

tfv/tfv_flying.s

@@ -828,34 +828,35 @@ spacez_shifted:
 			; NUM2H:NUM2L already set above
 	sec		; don't reuse previous NUM1			; 2
 	jsr	multiply						; 6
-	stx	SPACEX_I						; 3
+			; SPACEX_I in X					;
-	sta	SPACEX_F						; 3
+			; SPACEX_F in A					;
 								;==========
-								;	 26
+								;	 20
 
 	; fixed_add(&space_x,&cx,&space_x);
 	clc								; 2
-	lda	SPACEX_F						; 3
+			; SPACEX_F still in A				;
 	adc	CX_F							; 3
 	sta	SPACEX_F						; 3
-	lda	SPACEX_I						; 3
+	txa		; SPACEX_I was in X				; 2
 	adc	CX_I							; 3
 	sta	SPACEX_I						; 3
+								;===========
+								;	 16
 
 
-	; brk	; space_x = 06:bc
+	; temp.i=fixed_sin[angle&0xf].i; // sin()
-
+	lda	ANGLE							; 3
-	lda	ANGLE	; temp.i=fixed_sin[angle&0xf].i;		; 3
 	and	#$f							; 2
 	asl								; 2
 	tay								; 2
 	lda	fixed_sin,Y						; 4
-;	sta	TEMP_I							; 
+	sta	NUM2H		; store for next mul			; 3
-	sta	NUM2H							; 3
+
-	iny		; fixed_temp.f=fixed_sin[angle&0xf].f;		; 2
+	; fixed_temp.f=fixed_sin[angle&0xf].f; // sin()
+	iny								; 2
 	lda	fixed_sin,Y						; 4
-	sta	TEMP_F							;
+	sta	NUM2L		; store for next mul			; 3
-	sta	NUM2L							; 3
 								;==========
 								;	 25
 
@@ -865,25 +866,24 @@ spacez_shifted:
 	sta	NUM1H							; 3
 	lda	SPACEY_F						; 3
 	sta	NUM1L							; 3
-;	lda	TEMP_I							;
+				; NUM2H:NUM2L already set
-;	sta	NUM2H							;
+	sec			; don't reuse previous num1		; 2
-;	lda	TEMP_F							;
-;	sta	NUM2L							;
-	sec								; 2
 	jsr	multiply						; 6
-	stx	SPACEY_I						; 3
+				; SPACEY_I in X				;
-	sta	SPACEY_F						; 3
+				; SPACEY_F in A				;
 								;==========
-								;	 26
+								;	 20
 
-	clc			; fixed_add(&space_y,&cy,&space_y);	; 2
+	; fixed_add(&space_y,&cy,&space_y);
-	lda	SPACEY_F						; 3
+	clc								; 2
+				; SPACEY_F in A
 	adc	CY_F							; 3
 	sta	SPACEY_F						; 3
-	lda	SPACEY_I						; 3
+	txa			; SPACEY_I in X				; 2
 	adc	CY_I							; 3
 	sta	SPACEY_I						; 3
-
+								;==========
+								;	 16
 ; mul7
 	; fixed_mul(&temp,&dx,&temp);
 	lda	#CONST_LOWRES_HALF_I					; 3