N EQU 13

				AREA 	imageArea, DATA, READONLY
image			DCB 0x01, 0x01, 0x01, 0x02, 0x03, 0x01, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x02

				AREA	zipArea, DATA, READWRITE
compressed		SPACE 2*N

                AREA    |.text|, CODE, READONLY


; Reset Handler

Reset_Handler   PROC
                EXPORT  Reset_Handler             [WEAK]

				LDR R0, =image
				LDR R1, =compressed
				PUSH {R0, R1}
				BL compression
				POP {R0, R1}

				LDR R0, =N
				LDR R1, =compressed
				PUSH {R0, R1}
				BL compressionStats
				POP {R0, R1}

				LDR R0, =5   ; res: 3
				LDR R1, =compressed
				PUSH {R0, R1}
				BL findSymbol
				POP {R0, R1}

				LDR R0, =13  ; res :2
				LDR R1, =compressed
				PUSH {R0, R1}
				BL findSymbol
				POP {R0, R1}

				LDR R0, =6   ; res: 1
				LDR R1, =compressed
				PUSH {R0, R1}
				BL findSymbol
				POP {R0, R1}


stop			B stop
                ENDP
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;  ++ R1, R0, .. ----
compression		PROC
				PUSH {r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, lr}
				LDR R0, [SP, #48]
				LDR R1, [SP, #52]
				EOR R5, R5, R5   ; contatore
				EOR R4, R4, R4   ; flag uguale
				EOR R6, R6, R6   ; totale

				SUB R0, R0, #1
				SUB R1, R1, #1
preleva
				EOR R5, R5, R5
				ADD R7, R0, #1   ; salvo R0+1 in una var temporanea
				LDRB R2, [R0, #1]!
				LDRB R3, [R0, #1]!
				ADD R5, R5, #1
				CMP R2, R3
				BNE contadiverse
contauguali
				LDRB R2, [R0, #1]!
				ADD R5, R5, #1
				CMP R2, R3
				BNE finesequg
				B contauguali
contadiverse2
				MOV R3, R2
contadiverse
				LDRB R2, [R0, #1]!
				ADD R5, R5, #1
				CMP R2, R3
				BEQ fineseqdiv
				B contadiverse2
finesequg
				SUB R5, R5, #1
				STRB R5, [R1, #1]!
				STRB R3, [R1, #1]!
				ADD R9, R5, #1   ; per salvarlo nel contatore
				B next
fineseqdiv
				SUB R5, R5, #3  ; gli ultimi due che preleva sono uguali + 1 per l'algoritmo
				ORR R5, R5, #0x00000080
				STRB R5, [R1, #1]!
				AND R5, R5, #0xFFFFFF7F
				ADD R5, R5, #1 ; per la stampa
				MOV R9, R5
salvaseqdiv
				LDRB R8, [R7, #1]!
				STRB R8, [R1,#1]!
				SUB R5, R5, #1
				CMP R5, #0
				BHI	salvaseqdiv
next
				SUB R0, R0, #2
				ADD R6, R6, R9
				CMP R6, #N
				BLO preleva

				POP {r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, pc}
				ENDP
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

compressionStats	PROC
				PUSH {r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, lr}
				LDR R0, [SP, #48]	; numero originale di byte
				LDR R1, [SP, #52]	; puntatore vettore

				SUB R1, R1, #1

contbyte
				LDRB R3, [R1, #1]!
				ADD  R2, R2, #1
				CMP R3, #0
				BNE contbyte

				SUB R2, R2, #1  ; numero bute vettore compresso
				LDR R6, =100
				MUL R5, R2, R6
				UDIV R5, R5, R0			; R5 = nbyte/N
				SUB R4, R6, R5		; fattore compressione

				STR R4, [SP, #48]
				POP {r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, pc}
				ENDP
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

findSymbol		PROC
				PUSH {r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, lr}
				LDR R0, [SP, #48]  ; i-esimo simbolo della immagine
				LDR R1, [SP, #52]  ; compressa

				EOR R3, R3, R3		; indice reale nel vettore originale
				; considero una posizione umana (si parte da 1)
leggi
				MOV R7, R1
				LDRB R2, [R1]
				CMP R2, #0x00000080
				BHS divseq
eqseq
				ADD R2, R2, #1
				ADD R1, R1, #2
				ADD R3, R3, R2
				B try
divseq
				AND R2, R2, #0x0000007F
				ADD R2, R2, #1
				ADD R3, R3, R2
				ADD R1, R1, R2
				ADD R1, R1, #1
				ADD R2, R2, #0x00000080
try
				CMP R0, R3
				BLS	found
				B leggi
found
				CMP R2, #0x00000080
				BLO findeq
finddiv
				AND R2, R2, #0x0000007F
				SUB R3, R3, R2
cicla
				ADD R7, R7, #1
				ADD R3, R3, #1
				CMP R3, R0
				BNE cicla
				LDRB R5, [R7]
				B then
findeq
				LDRB R5, [R7, #1]

then
				STR R5, [SP, #48]
				POP {r0, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10, pc}
				ENDP