tfv: optimize the multiply some more

gr-sim/tfv_flying_6502.c

@@ -43,8 +43,6 @@
 #define SPEED		0x7b
 #define SPLASH_COUNT	0x7c
 #define OVER_WATER	0x7d
-#define TEMP2_I		0x7e
-#define TEMP2_F		0x7f
 
 #define SHIPY		0xE4
 
@@ -57,6 +55,10 @@
 
 #define CONST_SHIPX	15
 
+#define CONST_LOWRES_HALF_I	0xec	// -20 (LOWRES_W/2)
+#define CONST_LOWRES_HALF_F	0x0
+
+
 /* Mode7 code based on code from: */
 /* http://www.helixsoft.nl/articles/circle/sincos.htm */
 
@@ -562,7 +564,7 @@ y_positive:
 
 //	return (product[3]<<24)|(product[2]<<16)|(product[1]<<8)|product[0];
 						// rts			; 6
-					cycles.multiply+=6;
+					cycles.multiply+=12;
 }
 
 
@@ -786,9 +788,9 @@ void draw_background_mode7(void) {
 	hlin_double(ram[DRAW_PAGE], 0, 40, 6);
 						cycles.mode7+=14+63+(16*40);
 
-						cycles.mode7+=28;
+						cycles.mode7+=30;
 	/* FIXME: only do this if SPACEZ changes? */
-// mul
+// mul1
 	fixed_mul(ram[SPACEZ_I],ram[SPACEZ_F],
 		CONST_BETA_I,CONST_BETA_F,
 		&ram[FACTOR_I],&ram[FACTOR_F],0);
@@ -804,7 +806,7 @@ void draw_background_mode7(void) {
 //		fixed_to_double(ram[SPACEZ_I],ram[SPACEZ_F],),
 //		fixed_to_double(&BETA),
 //		fixed_to_double(ram[FACTOR_I],ram[FACTOR_F]));
-							cycles.mode7+=22;
+							cycles.mode7+=12;
 
 	for (ram[SCREEN_Y] = 8; ram[SCREEN_Y] < LOWRES_H; ram[SCREEN_Y]+=2) {
 
@@ -825,11 +827,11 @@ void draw_background_mode7(void) {
 			ram[HORIZ_SCALE_I],ram[HORIZ_SCALE_F]);
 		}
 
-//mul		// calculate the distance of the line we are drawing
+//mul2		// calculate the distance of the line we are drawing
 		fixed_mul(ram[HORIZ_SCALE_I],ram[HORIZ_SCALE_F],
 			CONST_SCALE_I,CONST_SCALE_F,
 			&ram[DISTANCE_I],&ram[DISTANCE_F],0);
-							cycles.mode7+=44;
+							cycles.mode7+=34;
 		if (!displayed) {
 			printf("DISTANCE %x:%x\n",ram[DISTANCE_I],ram[DISTANCE_F]);
 		}
@@ -840,11 +842,11 @@ void draw_background_mode7(void) {
 		ram[DX_F]=fixed_sin[(ram[ANGLE]+8)&0xf].f;	// -sin()
 							cycles.mode7+=29;
 
-// mul
+// mul3
 		fixed_mul(ram[HORIZ_SCALE_I],ram[HORIZ_SCALE_F],
 			ram[DX_I],ram[DX_F],
 			&ram[DX_I],&ram[DX_F],1);
-							cycles.mode7+=48;
+							cycles.mode7+=26;
 		if (!displayed) {
 			printf("DX %x:%x\n",ram[DX_I],ram[DX_F]);
 		}
@@ -853,11 +855,11 @@ void draw_background_mode7(void) {
 		ram[DY_I]=fixed_sin[(ram[ANGLE]+4)&0xf].i;	// cos()
 		ram[DY_F]=fixed_sin[(ram[ANGLE]+4)&0xf].f;	// cos()
 							cycles.mode7+=29;
-// mul
+// mul4
 		fixed_mul(ram[HORIZ_SCALE_I],ram[HORIZ_SCALE_F],
 			ram[DY_I],ram[DY_F],
 			&ram[DY_I],&ram[DY_F],1);
-							cycles.mode7+=48;
+							cycles.mode7+=28;
 		if (!displayed) {
 			printf("DY %x:%x\n",ram[DY_I],ram[DY_F]);
 		}
@@ -874,11 +876,11 @@ void draw_background_mode7(void) {
 		ram[TEMP_I]=fixed_sin[(ram[ANGLE]+4)&0xf].i; // cos
 		ram[TEMP_F]=fixed_sin[(ram[ANGLE]+4)&0xf].f; // cos
 							cycles.mode7+=29;
-// mul
+// mul5
 		fixed_mul(ram[SPACEX_I],ram[SPACEX_F],
 			ram[TEMP_I],ram[TEMP_F],
 			&ram[SPACEX_I],&ram[SPACEX_F],0);
-							cycles.mode7+=48;
+							cycles.mode7+=38;
 
 		fixed_add(ram[SPACEX_I],ram[SPACEX_F],
 			ram[CX_I],ram[CX_F],
@@ -888,25 +890,22 @@ void draw_background_mode7(void) {
 		ram[TEMP_I]=fixed_sin[ram[ANGLE]&0xf].i;
 		ram[TEMP_F]=fixed_sin[ram[ANGLE]&0xf].f;
 							cycles.mode7+=25;
-// mul
+// mul6
 		fixed_mul(ram[SPACEY_I],ram[SPACEY_F],
 			ram[TEMP_I],ram[TEMP_F],
 			&ram[SPACEY_I],&ram[SPACEY_F],0);
-							cycles.mode7+=48;
+							cycles.mode7+=38;
+
 		fixed_add(ram[SPACEY_I],ram[SPACEY_F],
 			ram[CY_I],ram[CY_F],
 			&ram[SPACEY_I],&ram[SPACEY_F]);
 
 
-		ram[TEMP2_I]=0xec;	// -20 (LOWRES_W/2)
-		ram[TEMP2_F]=0;
-							cycles.mode7+=30;
-
-// mul
-		fixed_mul(ram[TEMP2_I],ram[TEMP2_F],
+// mul7
+		fixed_mul(CONST_LOWRES_HALF_I,CONST_LOWRES_HALF_F,
 			ram[DX_I],ram[DX_F],
 			&ram[TEMP_I],&ram[TEMP_F],0);
-							cycles.mode7+=48;
+							cycles.mode7+=38;
 
 		fixed_add(ram[SPACEX_I],ram[SPACEX_F],
 			ram[TEMP_I],ram[TEMP_F],
@@ -917,15 +916,11 @@ void draw_background_mode7(void) {
 			ram[SPACEX_I],ram[SPACEX_F]);
 		}
 
-
-//		ram[TEMP_I]=0xec;	// -20 (LOWRES_W/2)
-//		ram[TEMP_F]=0;
-							cycles.mode7+=30;
-// mul
-		fixed_mul(ram[TEMP2_I],ram[TEMP2_F],
+// mul8
+		fixed_mul(CONST_LOWRES_HALF_I,CONST_LOWRES_HALF_F,
 			ram[DY_I],ram[DY_F],
 			&ram[TEMP_I],&ram[TEMP_F],1);
-							cycles.mode7+=48;
+							cycles.mode7+=26;
 		fixed_add(ram[SPACEY_I],ram[SPACEY_F],
 			ram[TEMP_I],ram[TEMP_F],
 			&ram[SPACEY_I],&ram[SPACEY_F]);
@@ -983,16 +978,16 @@ int flying(void) {
 	memset(&cycles,0,sizeof(cycles));
 	fixed_mul(0x1,0x0,
 		0x2,0x0,
-		&ram[FACTOR_I],&ram[FACTOR_F],0);
+		&ram[TEMP_I],&ram[TEMP_F],0);
 	printf("Multiplying 1.0 * 2.0 = %d.%d, took %d cycles\n",
-		ram[FACTOR_I],ram[FACTOR_F],cycles.multiply);
+		ram[TEMP_I],ram[TEMP_F],cycles.multiply);
 
 	memset(&cycles,0,sizeof(cycles));
 	fixed_mul(0xff,0xff,
 		0xff,0xff,
-		&ram[FACTOR_I],&ram[FACTOR_F],0);
+		&ram[TEMP_I],&ram[TEMP_F],0);
 	printf("Multiplying ff.ff * ff.ff = %d.%d, took %d cycles\n",
-		ram[FACTOR_I],ram[FACTOR_F],cycles.multiply);
+		ram[TEMP_I],ram[TEMP_F],cycles.multiply);
 
 	gr();
 	clear_bottom(PAGE0);

tfv/OPTIMIZATION

@@ -42,3 +42,19 @@ Update to use "fast multiply" w 2kB squares table lookup:
 	=================================
 	Total =                  139,833
 	Frame Rate = 7.15 fps
+
+Update to optimize fast multiply (reusing NUM1H, return results in register)
+	Multiplying 1.0 * 2.0 = 2.0, took 234 cycles
+	Multiplying ff.ff * ff.ff = 0.0, took 278 cycles
+
+	Cycles: flying=              162
+	Cycles: getkey=               46
+        Cycles: page_flip=            26
+        Cycles: multiply=         24,935
+        Cycles: mode7=            73,925
+        Cycles: lookup_map=       33,920
+        Cycles: put_sprite=        2,561
+	=================================
+        Total =                  135,575
+	Frame Rate = 7.38 fps
+

tfv/TODO

@@ -4,6 +4,8 @@ mode7 speed fixes:
 	+ faster multiply routine
 	+ If result is AABBCCDD we only need BBCC for fixed point
 		result
+	+ Pass NUM1H in A? no because used multiple places
+	+ inline hlin_setup? (save 12 cycles)
 
 	+ re-arrange variables to better take advantage of self-modifying code
 	+ only doing the spacez calculation if it has changed

tfv/tfv_flying.s

@@ -11,7 +11,8 @@ CONST_BETA_I	EQU	$ff
 CONST_BETA_F	EQU	$80
 CONST_SCALE_I	EQU	$14
 CONST_SCALE_F	EQU	$00
-
+CONST_LOWRES_HALF_I	EQU	$ec	; -(LOWRES_W/2)
+CONST_LOWRES_HALF_F	EQU	$00	
 
 flying_start:
 
@@ -553,7 +554,7 @@ sky_loop:				; draw line across screen
 	bne	sky_loop						; 3/2nt
 								;=============
 								; (23+63+(X*16))*5
-	; Draw Horizon
+	; Draw Hazy Horizon
 
 	lda	#COLOR_BOTH_GREY	; Horizon is Grey		; 2
 	sta	COLOR							; 3
@@ -564,8 +565,9 @@ sky_loop:				; draw line across screen
 	jsr	hlin_double		; hlin	0,40 at 6	; 63+(X*16)
 								;===========
 								; 63+(X*16)+14
+	; FIXME: only do this if Z changes?
 	; fixed_mul(&space_z,&BETA,&factor);
-
+;mul1
 	lda	SPACEZ_I						; 3
 	sta	NUM1H							; 3
 	lda	SPACEZ_F						; 3
@@ -581,10 +583,8 @@ sky_loop:				; draw line across screen
 								;===========
 								;        30
 
-	lda	RESULT+2						; 4
-	sta	FACTOR_I						; 4
-	lda	RESULT+1						; 4
-	sta	FACTOR_F						; 4
+	sta	FACTOR_I						; 3
+	stx	FACTOR_F						; 3
 
 	;; SPACEZ=78  * ff80 = FACTOR=66
 
@@ -595,7 +595,7 @@ sky_loop:				; draw line across screen
 	lda	#8							; 2
 	sta	SCREEN_Y						; 4
 								;=============
-								;	 22
+								;	 12
 screeny_loop:
 	ldy	#0							; 2
 	jsr	hlin_setup		; y-coord in a, x-coord in y	; 41
@@ -629,25 +629,23 @@ screeny_loop:
 								;============
 								;	 44
 	;; brk ASM, horiz_scale = 00:73
-
+; mul2
 	; calculate the distance of the line we are drawing
 	; fixed_mul(&horizontal_scale,&scale,&distance);
 	lda	HORIZ_SCALE_I						; 3
-	sta	NUM1H							; 4
+	sta	NUM1H							; 3
 	lda	HORIZ_SCALE_F						; 3
-	sta	NUM1L							; 4
+	sta	NUM1L							; 3
 	lda	#CONST_SCALE_I	; SCALE_I				; 2
-	sta	NUM2H							; 4
+	sta	NUM2H							; 3
 	lda	#CONST_SCALE_F	; SCALE_F				; 2
-	sta	NUM2L							; 4
+	sta	NUM2L							; 3
 	sec								; 2
 	jsr	multiply						; 6
-	lda	RESULT+2						; 4
 	sta	DISTANCE_I						; 2
-	lda	RESULT+1						; 4
-	sta	DISTANCE_F						; 2
+	stx	DISTANCE_F						; 2
 								;==========
-								;	 46
+								;	 34
 	;; brk ASM, distance = 08:fc
 
 	; calculate the dx and dy of points in space when we step
@@ -666,24 +664,22 @@ screeny_loop:
 	sta	DX_F							; 3
 								;==========
 								;	 29
-
+;mul3
 	; fixed_mul(&dx,&horizontal_scale,&dx);
-	lda	HORIZ_SCALE_I						; 3
-	sta	NUM1H							; 4
-	lda	HORIZ_SCALE_F						; 3
-	sta	NUM1L							; 4
+;	lda	HORIZ_SCALE_I
+;	sta	NUM1H
+;	lda	HORIZ_SCALE_F
+;	sta	NUM1L
 	lda	DX_I							; 3
-	sta	NUM2H							; 4
+	sta	NUM2H							; 3
 	lda	DX_F							; 3
-	sta	NUM2L							; 4
-	sec								; 2
+	sta	NUM2L							; 3
+	clc			; reuse HORIZ_SCALE in NUM1		; 2
 	jsr	multiply						; 6
-	lda	RESULT+2						; 4
 	sta	DX_I							; 3
-	lda	RESULT+1						; 4
-	sta	DX_F							; 3
+	stx	DX_F							; 3
 								;==========
-								;	 48
+								;	 26
 	;; ANGLE
 	;; brk ASM, dx = 00:00
 
@@ -700,23 +696,22 @@ screeny_loop:
 	sta	DY_F							; 3
 								;==========
 								;	 29
+;mul4
 	; fixed_mul(&dy,&horizontal_scale,&dy);
-	lda	HORIZ_SCALE_I						; 3
-	sta	NUM1H							; 4
-	lda	HORIZ_SCALE_F						; 3
-	sta	NUM1L							; 4
+;	lda	HORIZ_SCALE_I
+;	sta	NUM1H
+;	lda	HORIZ_SCALE_F
+;	sta	NUM1L
 	lda	DY_I							; 3
 	sta	NUM2H							; 4
 	lda	DY_F							; 3
 	sta	NUM2L							; 4
-	sec								; 2
+	clc			; reuse horiz_scale in num1		; 2
 	jsr	multiply						; 6
-	lda	RESULT+2						; 4
 	sta	DY_I							; 3
-	lda	RESULT+1						; 4
-	sta	DY_F							; 3
+	stx	DY_F							; 3
 								;==========
-								;	 48
+								;	 28
 	;; brk ASM, dy = 00:73
 
 	; calculate the starting position
@@ -749,23 +744,22 @@ screeny_loop:
 								;==========
 								;	 29
 
+; mul5
 	; fixed_mul(&space_x,&temp,&space_x);
 	lda	SPACEX_I						; 3
-	sta	NUM1H							; 4
+	sta	NUM1H							; 3
 	lda	SPACEX_F						; 3
-	sta	NUM1L							; 4
+	sta	NUM1L							; 3
 	lda	TEMP_I							; 3
-	sta	NUM2H							; 4
+	sta	NUM2H							; 3
 	lda	TEMP_F							; 3
-	sta	NUM2L							; 4
+	sta	NUM2L							; 3
 	sec								; 2
 	jsr	multiply						; 6
-	lda	RESULT+2						; 4
 	sta	SPACEX_I						; 3
-	lda	RESULT+1						; 4
-	sta	SPACEX_F						; 3
+	stx	SPACEX_F						; 3
 								;==========
-								;	 48
+								;	 38
 
 	clc			; fixed_add(&space_x,&cx,&space_x);	; 2
 	lda	SPACEX_F						; 3
@@ -775,41 +769,7 @@ screeny_loop:
 	adc	CX_I							; 3
 	sta	SPACEX_I						; 3
 
-	lda	#$ec		; temp.i=0xec;	// -20 (LOWRES_W/2)	; 2
-	sta	TEMP_I							; 3
-	lda	#0		; temp.f=0;				; 2
-	sta	TEMP_F							; 3
-								;==========
-								;	 30
-	; fixed_mul(&temp,&dx,&temp);
-	lda	TEMP_I							; 3
-	sta	NUM1H							; 4
-	lda	TEMP_F							; 3
-	sta	NUM1L							; 4
-	lda	DX_I							; 3
-	sta	NUM2H							; 4
-	lda	DX_F							; 3
-	sta	NUM2L							; 4
-	sec								; 2
-	jsr	multiply						; 6
-	lda	RESULT+2						; 4
-	sta	TEMP_I							; 3
-	lda	RESULT+1						; 4
-	sta	TEMP_F							; 3
-								;==========
-								;	 48
 
-
-
-	clc		; fixed_add(&space_x,&temp,&space_x);		; 2
-	lda	SPACEX_F						; 3
-	adc	TEMP_F							; 3
-	sta	SPACEX_F						; 3
-	lda	SPACEX_I						; 3
-	adc	TEMP_I							; 3
-	sta	SPACEX_I						; 3
-								;==========
-								;	 20
 	; brk	; space_x = 06:bc
 
 	lda	ANGLE	; temp.i=fixed_sin[angle&0xf].i;		; 3
@@ -824,23 +784,22 @@ screeny_loop:
 								;==========
 								;	 25
 
+;mul6
 	; fixed_mul(&space_y,&fixed_temp,&space_y);
 	lda	SPACEY_I						; 3
-	sta	NUM1H							; 4
+	sta	NUM1H							; 3
 	lda	SPACEY_F						; 3
-	sta	NUM1L							; 4
+	sta	NUM1L							; 3
 	lda	TEMP_I							; 3
-	sta	NUM2H							; 4
+	sta	NUM2H							; 3
 	lda	TEMP_F							; 3
-	sta	NUM2L							; 4
+	sta	NUM2L							; 3
 	sec								; 2
 	jsr	multiply						; 6
-	lda	RESULT+2						; 4
 	sta	SPACEY_I						; 3
-	lda	RESULT+1						; 4
-	sta	SPACEY_F						; 3
+	stx	SPACEY_F						; 3
 								;==========
-								;	 48
+								;	 38
 
 	clc			; fixed_add(&space_y,&cy,&space_y);	; 2
 	lda	SPACEY_F						; 3
@@ -850,29 +809,68 @@ screeny_loop:
 	adc	CY_I							; 3
 	sta	SPACEY_I						; 3
 
-	lda	#$ec		; temp.i=0xec;	// -20 (LOWRES_W/2)	; 2
-	sta	TEMP_I							; 3
-	lda	#0		; temp.f=0;				; 2
-	sta	TEMP_F							; 3
-								;==========
-								;	 30
-	; fixed_mul(&fixed_temp,&dy,&fixed_temp);
-	lda	TEMP_I							; 3
-	sta	NUM1H							; 4
-	lda	TEMP_F							; 3
-	sta	NUM1L							; 4
-	lda	DY_I							; 3
-	sta	NUM2H							; 4
-	lda	DY_F							; 3
-	sta	NUM2L							; 4
+
+;	lda	#$ec		; temp.i=0xec;	// -20 (LOWRES_W/2)	; 2
+;	sta	TEMP_I							; 3
+;	lda	#0		; temp.f=0;				; 2
+;	sta	TEMP_F							; 3
+;								;==========
+;
+								;	  0
+; mul7
+	; fixed_mul(&temp,&dx,&temp);
+	lda	#CONST_LOWRES_HALF_I					; 3
+	sta	NUM1H							; 3
+	lda	#CONST_LOWRES_HALF_F					; 3
+	sta	NUM1L							; 3
+	lda	DX_I							; 3
+	sta	NUM2H							; 3
+	lda	DX_F							; 3
+	sta	NUM2L							; 3
 	sec								; 2
 	jsr	multiply						; 6
-	lda	RESULT+2						; 4
 	sta	TEMP_I							; 3
-	lda	RESULT+1						; 4
-	sta	TEMP_F							; 3
+	stx	TEMP_F							; 3
 								;==========
-								;	 48
+								;	 38
+
+
+
+	clc		; fixed_add(&space_x,&temp,&space_x);		; 2
+	lda	SPACEX_F						; 3
+	adc	TEMP_F							; 3
+	sta	SPACEX_F						; 3
+	lda	SPACEX_I						; 3
+	adc	TEMP_I							; 3
+	sta	SPACEX_I						; 3
+								;==========
+								;	 20
+
+
+
+
+;	lda	#$ec		; temp.i=0xec;	// -20 (LOWRES_W/2)	; 2
+;	sta	TEMP_I							; 3
+;	lda	#0		; temp.f=0;				; 2
+;	sta	TEMP_F							; 3
+								;==========
+								;	 30
+;mul8
+	; fixed_mul(&fixed_temp,&dy,&fixed_temp);
+;	lda	#CONST_LOWRES_HALF_I
+;	sta	NUM1H
+;	lda	#CONST_LOWRES_HALF_F
+;	sta	NUM1L
+	lda	DY_I							; 3
+	sta	NUM2H							; 3
+	lda	DY_F							; 3
+	sta	NUM2L							; 3
+	clc	; reuse LOWRES_HALF_I from last time			; 2
+	jsr	multiply						; 6
+	sta	TEMP_I							; 3
+	stx	TEMP_F							; 3
+								;==========
+								;	 26
 
 	clc		; fixed_add(&space_y,&fixed_temp,&space_y);	; 2
 	lda	SPACEY_F						; 3

tfv/tfv_multiply.s

@@ -329,8 +329,10 @@ x_positive:
 								;	 19
 
 y_positive:
-;	*z_i=product[2];
-;	*z_f=product[1];
+	lda	RESULT+2	;	*z_i=product[2];		; 3
+	ldx	RESULT+1	;	*z_f=product[1];		; 3
 
-	rts								; 6
+
+
+	rts								; 12