disz80.asm

	SECTION	code_clib
	PUBLIC	disz80
	PUBLIC	_disz80
	PUBLIC	___disz80
	EXTERN	fputc_cons


;  This code is been found in a ZX Spectrum tool called UTILITY3 v1.3


.disz80
._disz80
.___disz80
	pop	hl
	pop	bc
	pop	de
	push	de
	push	bc
	push	hl
	push	ix	;save callers ix
	
	ld	a,d	;Supplying -1 as the address means we disassemble the following opcode
	and	e
	inc	a
	jr	nz,dizloop
	ld	hl,2
	add	hl,sp
	ld	e,(hl)
	inc	hl
	ld	d,(hl)
	
.dizloop
	push	bc
	call	DISASM
	pop	bc
	ld	a,13
	call	CHROP
	dec	bc
	ld	a,b
	or	c
	jr	nz,dizloop
	ld	h,d	;Address of next instruction
	ld	l,e
	pop	ix	;restore callers ix
	ret

; ====================
; DIS-Z80 was published in the SUBSET column of Personal Computer World 1987.
; The routine disassembles a single Z80 instruction at address DE. 
; It is required to be followed by a routine called CHROP that outputs a 
; single ASCII character.
; It was originally developed for CP/M on an Amstrad CPC128.

; The original ORG was $0100. I have added $5000 to all addresses.
; The stated aim was to write a Z80 disassembly routine in as short a space
; as possible and, at just over 1K (1090 bytes), it is a rather incredible 
; program. 

; The SUBSET editor David Barrow was able to trim only one byte from John 
; Kerr's compact code. I've forgotten where so there's a challenge.
; ====================

.DISASM	CALL 	ADRSP
       	LD 	BC,$0900
       	LD 	HL,$2020

.BUFFER	PUSH 	HL
       	DJNZ 	BUFFER
       	LD 	H,B
       	LD 	L,C
       	ADD 	HL,SP

       	PUSH 	BC
       	EX 	(SP),IX
       	PUSH 	BC
       	PUSH 	BC
       	ADD 	IX,SP

       	PUSH 	HL
       	LD 	HL,GROUP3

.TRYNDX	CALL 	FETCH

       	LD 	B,C
       	CP 	$ED
       	JR 	Z,CONFLG

       	INC 	B
       	CP 	$DD
       	JR 	Z,CONFLG

       	INC 	B
       	CP 	$FD
       	JR 	NZ,NOTNDX

.CONFLG	LD 	(IX+1),B
       	INC 	B
       	DJNZ 	TRYNDX

       	JR 	NXBYTE

.NOTNDX	LD 	C,A
       	LD 	A,(IX+1)
       	OR 	A
       	JR 	Z,NODISP

       	LD 	A,C
       	CP 	$CB
       	JR 	Z,GETDIS

       	AND 	$44
       	CP 	4
       	JR 	Z,GETDIS

       	LD 	A,C
       	AND 	$C0
       	CP 	$40
       	JR 	NZ,NODISP

.GETDIS	CALL 	FETCH
       	LD 	(IX+2),A

.NODISP	LD 	HL,GROUP1
       	LD 	A,C
       	CP 	$CB
       	JR 	NZ,NEWMSK

       	LD 	HL,GROUP2

.NXBYTE	CALL 	FETCH
       	LD 	C,A

.NEWMSK	LD 	A,(HL)
       	OR 	A
       	JR 	Z,TABEND

       	AND 	C
       	INC 	HL

.NEWMOD	LD 	B,(HL)
       	INC 	HL
       	INC 	B
       	JR 	Z,NEWMSK

.TRYMAT	CP 	(HL)
       	INC 	HL
       	JR 	Z,GETNDX

       	BIT 	7,(HL)
       	INC 	HL
       	JR 	Z,TRYMAT

       	JR 	NEWMOD

.GETNDX	LD 	A,(HL)
       	AND 	$7F
       	DEC 	B

.TABEND	POP 	HL
       	PUSH 	DE
       	PUSH 	HL

       	EX 	DE,HL
       	LD 	HL,MONICS
       	CALL 	XTRACT

       	POP 	HL
       	LD 	DE,5
       	ADD 	HL,DE
       	POP 	DE

       	LD 	A,B
       	AND 	$F0
       	JR 	Z,SECOND

       	RRA
       	RRA
       	RRA
       	RRA
       	PUSH 	BC

       	LD 	B,A
       	LD 	A,C
       	CALL 	OPRND1

       	POP 	BC
       	LD 	A,B
       	AND 	$0F
       	JR 	Z,OPDONE

       	LD 	(HL),44  		;,
       	INC 	HL

.SECOND	LD 	A,B
       	AND 	$0F

       	LD 	B,A
       	LD 	A,C
       	CALL 	NZ,OPRND2

.OPDONE	LD 	A,3
       	SUB 	(IX+0)

       	POP 	HL
       	POP 	HL
       	POP 	IX

       	JR 	C,OUTEXT

       	INC 	A
       	LD 	B,A
       	ADD 	A,B
       	ADD 	A,B
       	LD 	B,A

.SPACES	LD 	A,$20
       	CALL 	CHROP
       	DJNZ 	SPACES
       	
.OUTEXT	LD 	B,18

.PUTOUT	DEC 	SP
       	POP 	HL
       	LD 	A,H
       	CALL 	CHROP
       	DJNZ 	PUTOUT

       	RET

;***********************

.GROUP2	defb 	$C0,$36,$40
	defb 	$04,$80,$2D,$C0,$BE
	defb 	$FF,$F8,$06,$00,$33
	defb 	$08,$38,$10,$35,$18
	defb 	$3A,$20,$3F,$28,$40
	defb 	$30,$00,$38,$C1


.GROUP1	defb 	$FF,$00,$00
	defb 	$24,$07,$32,$0F,$37
	defb 	$17,$31,$1F,$36,$27
	defb 	$0D,$2F,$0B,$37,$3D
	defb 	$3F,$06,$76,$14,$C9
	defb 	$30,$D9,$12,$F3,$0F
	defb 	$FB,$91,$72,$C6,$02
	defb 	$CE,$01,$DE,$BC,$02
	defb 	$D6,$42,$E6,$03,$EE
	defb 	$43,$F6,$25,$FE,$8C
	defb 	$04,$08,$93,$01,$10
	defb 	$10,$18,$9D,$AF,$22
	defb 	$A2,$FA,$2A,$A2,$A7
	defb 	$32,$A2,$7A,$3A,$A2
	defb 	$03,$C3,$1C,$CD,$85
	defb 	$97,$D3,$AA,$79,$DB
	defb 	$9B,$5F,$E3,$93,$0E
	defb 	$E9,$9C,$05,$EB,$93
	defb 	$DF,$F9,$A2,$FF,$C0
	defb 	$B6,$40,$A2,$FF,$F8
	defb 	$76,$80,$02,$88,$01
	defb 	$98,$BC,$06,$90,$42
	defb 	$A0,$03,$A8,$43,$B0
	defb 	$25,$B8,$8C,$FF,$C7
	defb 	$0B,$04,$16,$05,$8E
	defb 	$B2,$06,$A2,$20,$C0
	defb 	$B0,$23,$C2,$1C,$C4
	defb 	$85,$10,$C7,$BB,$FF
	defb 	$CF,$D3,$01,$A2,$0D
	defb 	$03,$16,$0B,$8E,$FD
	defb 	$09,$82,$60,$C1,$2B
	defb 	$C5,$AC,$FF,$E7,$21
	defb 	$20,$9D,$FF,$EF,$E7
	defb 	$02,$A2,$7E,$0A,$A2


.GROUP3	defb 	$FF,$00,$44
	defb 	$23,$45,$2F,$4D,$2E
	defb 	$4E,$00,$67,$39,$6F
	defb 	$34,$70,$00,$71,$00
	defb 	$A0,$21,$A1,$0A,$A2
	defb 	$1A,$A3,$29,$A8,$1F
	defb 	$A9,$08,$AA,$18,$AB
	defb 	$28,$B0,$20,$B1,$09
	defb 	$B2,$19,$B3,$27,$B8
	defb 	$1E,$B9,$07,$BA,$17
	defb 	$BB,$A6,$FF,$C7,$B8
	defb 	$40,$9B,$8B,$41,$AA
	defb 	$FF,$CF,$FD,$42,$3C
	defb 	$4A,$81,$AD,$43,$A2
	defb 	$DA,$4B,$A2,$FF,$E7
	defb 	$40,$46,$95,$FF,$F7
	defb 	$C7,$47,$A2,$7C,$57
	defb 	$A2,$FF,$00

;_______________

.MONICS	defb 	$BF
	defb 	'A','D','C'+$80   	; ADC 
	defb 	'A','D','D'+$80   	; ADD 
	defb 	'A','N','D'+$80   	; AND 
	defb 	'B','I','T'+$80   	; BIT 
	defb 	'C','A','L','L'+$80	; CALL 
	defb 	'C','C','F'+$80   	; CCF
	defb 	'C','P','D','R'+$80	; CPDR
	defb 	'C','P','D'+$80   	; CPD
	defb 	'C','P','I','R'+$80	; CPIR
	defb 	'C','P','I'+$80   	; CPI
	defb 	'C','P','L'+$80   	; CPL
	defb 	'C','P'+$80      	; CP 
	defb 	'D','A','A'+$80   	; DAA
	defb 	'D','E','C'+$80   	; DEC 
	defb 	'D','I'+$80      	; DI
	defb 	'D','J','N','Z'+$80	; DJNZ 
	defb 	'E','I'+$80      	; EI
	defb 	'E','X','X'+$80   	; EXX
	defb 	'E','X'+$80      	; EX 
	defb 	'H','A','L','T'+$80	; HALT
	defb 	'I','M'+$80      	; IM 
	defb 	'I','N','C'+$80   	; INC 
	defb 	'I','N','D','R'+$80	; INDR
	defb 	'I','N','D'+$80   	; IND
	defb 	'I','N','I','R'+$80	; INIR
	defb 	'I','N','I'+$80   	; INI
	defb 	'I','N'+$80      	; IN 
	defb 	'J','P'+$80      	; JP 
	defb 	'J','R'+$80      	; JR 
	defb 	'L','D','D','R'+$80	; LDDR
	defb 	'L','D','D'+$80   	; LDD
	defb 	'L','D','I','R'+$80	; LDIR
	defb 	'L','D','I'+$80   	; LDI
	defb 	'L','D'+$80      	; LD 
	defb 	'N','E','G'+$80   	; NEG
	defb 	'N','O','P'+$80   	; NOP
	defb 	'O','R'+$80      	; OR 
	defb 	'O','T','D','R'+$80	; OTDR
	defb 	'O','T','I','R'+$80	; OTIR
	defb 	'O','U','T','D'+$80	; OUTD
	defb 	'O','U','T','I'+$80	; OUTI
	defb 	'O','U','T'+$80   	; OUT 
	defb 	'P','O','P'+$80   	; POP 
	defb 	'P','U','S','H'+$80	; PUSH 
	defb 	'R','E','S'+$80   	; RES 
	defb 	'R','E','T','I'+$80	; RETI
	defb 	'R','E','T','N'+$80	; RETN
	defb 	'R','E','T'+$80   	; RET
	defb 	'R','L','A'+$80   	; RLA
	defb 	'R','L','C','A'+$80	; RLCA
	defb 	'R','L','C'+$80   	; RLC 
	defb 	'R','L','D'+$80   	; RLD
	defb 	'R','L'+$80      	; RL 
	defb 	'R','R','A'+$80   	; RRA
	defb 	'R','R','C','A'+$80	; RA
	defb 	'R','R','C'+$80   	; RRC 
	defb 	'R','R','D'+$80   	; RRD
	defb 	'R','R'+$80      	; RR 
	defb 	'R','S','T'+$80   	; RST 
	defb 	'S','B','C'+$80   	; SBC 
	defb 	'S','C','F'+$80   	; SCF
	defb 	'S','E','T'+$80   	; SET 
	defb 	'S','L','A'+$80   	; SLA 
	defb 	'S','R','A'+$80   	; SRA 
	defb 	'S','R','L'+$80   	; SRL 
	defb 	'S','U','B'+$80   	; SUB 
	defb 	'X','O','R'+$80   	; XOR 



;*****************

.OPRND1	DJNZ 	CONDIT

.RSTADR	AND 	$38
       	JR 	DA

.OPRND2	DJNZ 	DAT8

.RELADR	CALL 	FETCH
       	LD 	C,A
       	RLA
       	SBC 	A,A
       	LD 	B,A
       	EX 	DE,HL
       	PUSH 	HL
       	ADD 	HL,BC
       	JR 	DHL

.CONDIT	RRA
       	RRA
       	RRA
       	DJNZ 	BITNUM

       	BIT 	4,A
       	JR 	NZ,ABS

       	AND 	3
	
.ABS   	AND 	7
       	ADD 	A,$14
       	JR 	PS1

.DAT8  	DJNZ 	DAT16

.D8    	CALL 	FETCH
       	JR 	DA

.BITNUM	DJNZ 	INTMOD
       	AND 	7

.DA    	LD 	C,A
       	SUB 	A
       	JR 	DAC

.DAT16 	DJNZ 	EXAF
	
.D16   	CALL 	FETCH
       	LD 	C,A
       	CALL 	FETCH

.DAC   	EX 	DE,HL
       	PUSH 	HL
       	LD 	H,A
       	LD 	L,C

.DHL   	LD 	C,$F8
       	PUSH 	HL
       	CALL 	CONVHL
       	POP 	HL
       	LD 	BC,$000A
       	OR 	A
       	SBC 	HL,BC
       	POP 	HL
       	EX 	DE,HL
       	RET 	C

       	LD 	(HL),'H'
       	INC 	HL
       	RET


.INTMOD	DJNZ 	STKTOP
       	AND 	3
       	ADD 	A,$1C
	
.PS1   	JR 	PS3

.STKTOP	LD 	C,$13
       	DEC 	B
       	JR 	Z,PS2

.REG16P	DJNZ 	COMMON
       	RRA
       	AND 	3
       	CP 	3
       	JR 	NZ,RX

       	DEC 	A
       	JR 	RNX

.EXAF  	LD 	C,$0A
       	DEC 	B
       	JR 	Z,PS2

.EXDE  	INC 	C
       	DEC 	B
       	JR 	Z,PS2

.REG8S 	DJNZ 	ACCUM

.R8    	AND 	7
       	CP 	6
       	JR 	NZ,PS3

       	LD 	(HL),'('
       	INC 	HL
       	CALL 	REGX
       	LD 	A,(IX+2)
       	OR 	A
       	JR 	Z,RP

       	LD 	(HL),43 		;+
       	RLCA
       	RRCA
       	JR 	NC,POS

       	LD 	(HL),45			;-
       	NEG

.POS   	INC 	HL
       	EX 	DE,HL
       	PUSH 	HL
       	LD 	H,B
       	LD 	L,A
       	LD 	C,$FB
       	CALL 	CONVHL
       	POP 	HL
       	EX 	DE,HL
       	JR 	RP

.ACCUM 	RRA
       	RRA
       	RRA

.COMMON	LD 	C,7
       	DEC 	B
       	JR 	Z,PS2

.PORTC 	DEC 	C
       	DJNZ 	IDAT8

.PS2   	LD 	A,C
.PS3   	JR 	PS4

.IDAT8 	DJNZ 	IDAT16
       	LD 	(HL),'('
       	INC 	HL
       	CALL 	D8
       	JR 	RP

.IDAT16	DJNZ 	REG8
       	LD 	(HL),'('
       	INC 	HL
       	CALL 	D16
       	JR 	RP

.REG8  	DEC 	B
       	JR 	Z,R8

.IPAREF 	DJNZ 	REG16
       	AND 	9
       	JR 	PS4

.REG16 	RRA
       	DJNZ 	IREG16

.R16   	AND 	3
.RX    	CP  	2
       	JR 	Z,REGX

.RNX   	ADD 	A,$0C
       	JR 	PS4

.IREG16	DJNZ 	REGX
       	LD 	(HL),'('
       	INC 	HL
       	CALL 	R16

.RP    	LD 	(HL),')'
       	INC 	HL
       	RET

.REGX  	LD 	A,(IX+1)
       	ADD 	A,$10

.PS4   	EX 	DE,HL
       	PUSH 	HL
       	LD 	HL,RGSTRS
       	CALL 	XTRACT
       	POP 	HL
       	EX 	DE,HL
       	RET

;*************

.RGSTRS	defb 	'B'				+$80
	defb 	'C'       			+$80
	defb 	'D'       			+$80
	defb 	'E'       			+$80
	defb 	'H'       			+$80
	defb 	'L'       			+$80
	defb 	'(','C',')' 			+$80
	defb 	'A'       			+$80
	defb 	'I'       			+$80
	defb 	'R'       			+$80
	defb 	'A','F',',','A','F','\''		+$80
	defb 	'D','E',',','H','L'    		+$80
	defb 	'B','C'             		+$80
	defb 	'D','E'             		+$80
	defb 	'A','F'             		+$80
	defb 	'S','P'             		+$80
	defb 	'H','L'             		+$80
	defb 	'I','X'             		+$80
	defb 	'I','Y'             		+$80
	defb 	'(','S','P',')'       		+$80
	defb 	'N','Z'             		+$80
	defb 	'Z'                		+$80
	defb 	'N','C'             		+$80
	defb 	'C'                		+$80
	defb 	'P','O'             		+$80
	defb 	'P','E'             		+$80
	defb 	'P'                		+$80
	defb 	'M'                		+$80
	defb 	'0'    				+$80
	defb 	'?'    				+$80
	defb 	'1'    				+$80
	defb 	'2'    				+$80

;********************

.CONVHL	SUB 	A

.CVHL1 	PUSH 	AF
       	SUB 	A
       	LD 	B,16

.CVHL2 	ADD 	A,C
       	JR 	C,CVHL3
       	SUB 	C

.CVHL3 	ADC 	HL,HL
       	RLA
       	DJNZ 	CVHL2

       	JR 	NZ,CVHL1

       	CP 	10
       	INC 	B
       	JR 	NC,CVHL1

.CVHL4 	CP 	10
       	SBC 	A,$69
       	DAA
       	LD 	(DE),A
       	INC 	DE
       	POP 	AF
       	JR 	NZ,CVHL4

       	RET

;****************

.XTRACT	OR 	A
       	JR 	Z,COPY

.SKIP  	BIT 	7,(HL)
       	INC 	HL
       	JR 	Z,SKIP

       	DEC 	A
       	JR 	NZ,SKIP

.COPY  	LD 	A,(HL)
       	RLCA
       	SRL 	A
       	LD 	(DE),A

       	INC 	DE
       	INC 	HL
       	JR 	NC,COPY

       	RET

;*******************

.FETCH 	LD 	A,(DE)
       	INC 	DE
       	INC 	(IX+0)
       	PUSH 	AF
       	CALL 	BYTSP
       	POP 	AF
       	RET

.ADRSP 	LD 	A,D
       	CALL 	BYTOP
       	LD 	A,E

.BYTSP 	CALL 	BYTOP
       	LD 	A,$20
       	JR 	CHROP

.BYTOP 	PUSH 	AF
       	RRA
       	RRA
       	RRA
       	RRA
       	CALL 	HEXOP
       	POP 	AF

.HEXOP 	AND 	$0F
       	CP 	10
       	SBC 	A,$69
       	DAA

; -----------------------------------
;
; End of John Kerr's DIS-Z80 routine.
; 
; The next routine outputs a character.
;
; -------------------------------------

.CHROP 	PUSH 	HL
       	PUSH 	DE
       	PUSH 	BC

	ld	h,0
	ld	l,a
	push	hl		; parameter passing
       	call 	fputc_cons	; This calls the Z88DK "put char" function
	pop	hl

       	POP 	BC
       	POP 	DE
       	POP 	HL

       	RET