.asciz	"PRG"
	stmfd	sp!,{r0-r12,lr}
	
	adr	r0,MagicBal
	mov	r1,#0
	mov	r2,#0
	adr	r9,dummy
	mov	r3,#1
	mov	r4,#2
	
BigLp:	bl	SPRITE

	bl	WtVsync
	
	bl	SPROFF
	
	add	r1,r3
	add	r2,r4
	
	cmp	r1,#0
	moveq	r3,#4	@ rsbeq	r3,r3,#0
	ldr	r5,=#304
	cmp	r1,r5
	moveq	r3,#-2	@ rsbeq	r3,r3,#0
	cmp	r2,#0
	moveq	r4,#1	@ rsbeq	r4,r4,#0
	cmp	r2,#224
	moveq	r4,#-4	@ rsbeq	r4,r4,#0
	
	bl	GETKEY
	cmp	r12,#74
	bne	BigLp
	
Fini:	ldmfd	sp!,{r0-r12,pc}
@_________________________________________________________________________

SPRITE:	@	CE: r0=pointeur vers sprite ; r9=pointeur de sauvegarde ; (r1,r2)=affichage en coord. (x,y) 
	stmfd	sp!,{r0-r12,lr}
	mov	r3,#0xc0000010
	ldr	r3,[r3]
	mov	r4,#640
	mla	r3,r4,r2,r3
	add	r3,r3,r1,lsl#1	@ r3=position à l'écran
	ldrh	r1,[r0],#2	@ r1=largeur
	sub	r4,r1,lsl#1
	ldrh	r2,[r0],#2	@ r2=hauteur
	str	r3,[r9],#4
	strh	r1,[r9],#2
	strh	r2,[r9],#2
	mov	r7,#0
sprht_lp:	mov	r10,r1
sprlg_lp:	ldrh	r8,[r3]
	strh	r8,[r9],#2
	ldrh	r6,[r0],#2
	cmp	r6,r7
	strneh	r6,[r3],#2
	addeq	r3,#2
	subs	r10,#1
	bne	sprlg_lp
	add	r3,r4
	subs	r2,#1
	bne	sprht_lp
	ldmfd	sp!,{r0-r12,pc}
@_________________________________________________________________________
	
SPROFF:	@	CE: r9=pointeur vers fond 
	stmfd	sp!,{r0-r12,lr}
	mov	r4,#640
	ldr	r3,[r9],#4
	ldrh	r1,[r9],#2	@ r1=largeur
	sub	r4,r1,lsl#1
	ldrh	r2,[r9],#2	@ r2=hauteur
sprhf_lp:	mov	r10,r1
sprlf_lp:	ldrh	r6,[r9],#2
	strh	r6,[r3],#2
	subs	r10,#1
	bne	sprlf_lp
	add	r3,r4
	subs	r2,#1
	bne	sprhf_lp
	ldmfd	sp!,{r0-r12,pc}
@_________________________________________________________________________

GETKEY:	stmfd	sp!,{r0,r2-r4,lr}		@ scrute le clavier
	mov	r12,#0
	ldr	r0,=#0x900e0010		@ en sortie: r12 contient le code-clavier (=0 si aucune touche pressée)
	b	wk_rtp
@_________________________________________________________________________

WAITKEY:	@ Attends qu'une touche soit pressée
	@ en entrée : rien ; en sortie: r12 contient un code "clavier" entre 1 et 88 ; les autres registres sont préservés
	stmfd	sp!,{r0,r2-r4,lr}	@ préserve les registres r0 ,r2 à r4 ainsi que le registre lr contenant l'adresse de retour
	ldr	r0,=#0x900e0010	@ L'état du clavier complet (hormis le TouchPad) débute en offset $10 de l'adresse $9000e0000
wk_lp:	ldm	r0,{r1-r4}	@ le tout transféré dans 4 registres: respectivement offsets $10-$12, $14-$16, $18-$1a, $1c-$1e
	orr	r1,r1,r2		@ Une touche pressée ?..
	orr	r2,r3,r4		@ Quelques "ou" logiques de tout ça nous renseigneront...
	orrs	r1,r1,r2		@ Ainsi,
	beq	wk_lp		@ On boucle tant qu'une touche n'est pas pressée (c-à-d tant que r1 or r2 or r3 or r4 = 0)	
wk_rtp:	mov	r3,#0		@ au départ , rang = 0
	mov	r4,#8		@ 8 paquets de 11 bits à analyser (bit0 à 10) par emplacement (offset)
key_lp:	mov	r2,#0
	ldrh	r2,[r0],#2	@ on démarre en offset $10
	clz	r2,r2		@ En partant du bit 31, combien de bits nuls avant de tomber sur un bit à 1 ?..
	rsbs	r2,r2,#32		@ 32-résultat =valeur entre 1 et 11 si l'une des touches est pressée (sinon=0)
	addne	r12,r2,r3		@ non nul?..Alors r1=valeur + rang
	add	r3,#11		@ avant d'analyser le paquet de 11bits suivant, incrémente le rang de 11
	subs	r4,#1		@ Encore des paquets de bits à scruter ?
	bne	key_lp		@ Alors on continue...Au final, r12 contiendra une valeur entre 1 et 88
	ldmfd	sp!,{r0,r2-r4,pc}	@ les registres r0,r2 à r5 retrouvent leurs valeurs préalables ; puis écrit le contenu du
				@ registre lr dans le registre pc pour retourner (juste après) là où la sous-routine avait été appelée
@_________________________________________________________________________		
		
WtVsync:	stmfd	sp!,{r0-r1,lr}        
	mov        	r0,#0xC0000008                
	str        	r0,[r0,#32]
wvs_lp:	ldr        	r1,[r0,#24]
	ands        r1,r0
	beq	wvs_lp
	ldmfd	sp!,{r0-r1,pc}
@_________________________________________________________________________		
		
	.align
MagicBal:	.short	16,16
	.short	0x0000,0x0000,0x0000,0x0000,0x0000,0xb014,0xa815,0xa814,0xa814,0xb014,0xb814,0x0000,0x0000,0x0000,0x0000,0x0000
	.short	0x0000,0x0000,0x0000,0xb012,0x9015,0x9015,0x9816,0xa897,0xb0f8,0xb918,0xb8d6,0xb855,0xb012,0x0000,0x0000,0x0000
	.short	0x0000,0x0000,0x8814,0x8016,0x8817,0x7016,0xa2b9,0xbbfa,0x91b7,0x99d7,0xa9d8,0xc1b9,0xb8d6,0xb013,0x0000,0x0000
	.short	0x0000,0x9813,0x7015,0x7018,0x5816,0x6937,0x8259,0x8a79,0x79b8,0x81b8,0x91b7,0x99d7,0xb1b8,0xb076,0xb013,0x0000
	.short	0x0000,0x6815,0x6018,0x4016,0x4877,0x61d8,0x5998,0x6198,0x69b8,0x71b8,0x79b8,0x8997,0xb359,0xcafa,0xa814,0x0000
	.short	0x6816,0x5016,0x4879,0x38b9,0x4118,0x5239,0x4a19,0x49f9,0x51b9,0x5998,0x69b8,0x7998,0xa319,0xb319,0xa836,0xa813
	.short	0x5016,0x4017,0x40fa,0x41fc,0x3a5a,0x4b7b,0x4b9b,0x4b9b,0x5b5b,0x62ba,0x59d9,0x69b8,0x7998,0x91b7,0xa077,0xa014
	.short	0x4016,0x3818,0x2078,0x19fa,0x2b9b,0x4cdd,0x44dd,0x4cbd,0x9e1e,0xadbd,0x5a7a,0x5998,0x71b8,0x81b8,0x9037,0x9814
	.short	0x3816,0x2818,0x1979,0x131b,0x1c7d,0x45be,0x45fe,0x55fe,0x863e,0x95bd,0x5b5b,0x51b9,0x69d8,0x7137,0x8017,0x9015
	.short	0x3016,0x2058,0x1a1a,0x13dc,0x0d1e,0x4e7e,0x875e,0x66be,0x45de,0x4cdd,0x435b,0x5239,0x5978,0x5836,0x8017,0x8815
	.short	0x3815,0x2097,0x1a5b,0x13fc,0x155e,0x56fe,0x97de,0x7f3e,0x45fe,0x44fd,0x4b9b,0x4199,0x48b7,0x5876,0x7817,0x8815
	.short	0x0000,0x2098,0x1a1c,0x13bc,0x151e,0x569e,0x5efe,0x365e,0x1d3e,0x23fc,0x225a,0x1817,0x5958,0x7959,0x6815,0xf80f
	.short	0x0000,0x1815,0x1979,0x1b1d,0x1c5d,0x6e5f,0x2d9e,0x0cfe,0x0c3d,0x12fb,0x1959,0x2017,0x4017,0x6016,0x7016,0x0000
	.short	0x0000,0x0000,0x20d8,0x19da,0x1b1d,0x1bdd,0x13fc,0x13bc,0x131b,0x19d9,0x2078,0x3818,0x5017,0x6015,0x0000,0x0000
	.short	0x0000,0x0000,0x0000,0x2015,0x19ba,0x1a1a,0x1a5c,0x1a1c,0x215b,0x2079,0x3017,0x4017,0x5016,0x0000,0x0000,0x0000
	.short	0x0000,0x0000,0x0000,0x0000,0x0000,0x2057,0x20f9,0x2098,0x2017,0x2817,0x4017,0x0000,0x0000,0x0000,0x0000,0x0000
	.align
dummy:	.long	0x00000000
	.short	16,16
	.short	0x0000,0x0000,0x0000,0x0000,0x0000,0xb014,0xa815,0xa814,0xa814,0xb014,0xb814,0x0000,0x0000,0x0000,0x0000,0x0000
	.short	0x0000,0x0000,0x0000,0xb012,0x9015,0x9015,0x9816,0xa897,0xb0f8,0xb918,0xb8d6,0xb855,0xb012,0x0000,0x0000,0x0000
	.short	0x0000,0x0000,0x8814,0x8016,0x8817,0x7016,0xa2b9,0xbbfa,0x91b7,0x99d7,0xa9d8,0xc1b9,0xb8d6,0xb013,0x0000,0x0000
	.short	0x0000,0x9813,0x7015,0x7018,0x5816,0x6937,0x8259,0x8a79,0x79b8,0x81b8,0x91b7,0x99d7,0xb1b8,0xb076,0xb013,0x0000
	.short	0x0000,0x6815,0x6018,0x4016,0x4877,0x61d8,0x5998,0x6198,0x69b8,0x71b8,0x79b8,0x8997,0xb359,0xcafa,0xa814,0x0000
	.short	0x6816,0x5016,0x4879,0x38b9,0x4118,0x5239,0x4a19,0x49f9,0x51b9,0x5998,0x69b8,0x7998,0xa319,0xb319,0xa836,0xa813
	.short	0x5016,0x4017,0x40fa,0x41fc,0x3a5a,0x4b7b,0x4b9b,0x4b9b,0x5b5b,0x62ba,0x59d9,0x69b8,0x7998,0x91b7,0xa077,0xa014
	.short	0x4016,0x3818,0x2078,0x19fa,0x2b9b,0x4cdd,0x44dd,0x4cbd,0x9e1e,0xadbd,0x5a7a,0x5998,0x71b8,0x81b8,0x9037,0x9814
	.short	0x3816,0x2818,0x1979,0x131b,0x1c7d,0x45be,0x45fe,0x55fe,0x863e,0x95bd,0x5b5b,0x51b9,0x69d8,0x7137,0x8017,0x9015
	.short	0x3016,0x2058,0x1a1a,0x13dc,0x0d1e,0x4e7e,0x875e,0x66be,0x45de,0x4cdd,0x435b,0x5239,0x5978,0x5836,0x8017,0x8815
	.short	0x3815,0x2097,0x1a5b,0x13fc,0x155e,0x56fe,0x97de,0x7f3e,0x45fe,0x44fd,0x4b9b,0x4199,0x48b7,0x5876,0x7817,0x8815
	.short	0x0000,0x2098,0x1a1c,0x13bc,0x151e,0x569e,0x5efe,0x365e,0x1d3e,0x23fc,0x225a,0x1817,0x5958,0x7959,0x6815,0xf80f
	.short	0x0000,0x1815,0x1979,0x1b1d,0x1c5d,0x6e5f,0x2d9e,0x0cfe,0x0c3d,0x12fb,0x1959,0x2017,0x4017,0x6016,0x7016,0x0000
	.short	0x0000,0x0000,0x20d8,0x19da,0x1b1d,0x1bdd,0x13fc,0x13bc,0x131b,0x19d9,0x2078,0x3818,0x5017,0x6015,0x0000,0x0000
	.short	0x0000,0x0000,0x0000,0x2015,0x19ba,0x1a1a,0x1a5c,0x1a1c,0x215b,0x2079,0x3017,0x4017,0x5016,0x0000,0x0000,0x0000
	.short	0x0000,0x0000,0x0000,0x0000,0x0000,0x2057,0x20f9,0x2098,0x2017,0x2817,0x4017,0x0000,0x0000,0x0000,0x0000,0x0000