From 2682bc5d1d864341aaeb42a449db73c3ecd16d70 Mon Sep 17 00:00:00 2001
From: "Juan J. Martinez" <jjm@usebox.net>
Date: Wed, 30 Dec 2020 19:07:31 +0000
Subject: Initial import

---
 tools/rasm/decrunch/aplib_z80_todo.asm | 190 +++++++++++++++++++++++++++++++++
 1 file changed, 190 insertions(+)
 create mode 100644 tools/rasm/decrunch/aplib_z80_todo.asm

(limited to 'tools/rasm/decrunch/aplib_z80_todo.asm')

diff --git a/tools/rasm/decrunch/aplib_z80_todo.asm b/tools/rasm/decrunch/aplib_z80_todo.asm
new file mode 100644
index 0000000..6843a14
--- /dev/null
+++ b/tools/rasm/decrunch/aplib_z80_todo.asm
@@ -0,0 +1,190 @@
+;Z80 Version by Dan Weiss
+;Call depack.
+;hl = source
+;de = dest
+
+ap_bits: .db 0
+ap_byte: .db 0
+lwm:	.db 0
+r0:	.dw 0
+
+ap_getbit:
+	push bc
+		ld bc,(ap_bits)
+		rrc c
+		jr nc,ap_getbit_continue
+		ld b,(hl)
+		inc hl
+ap_getbit_continue:
+		ld a,c
+		and b
+		ld (ap_bits),bc
+	pop bc
+	ret
+
+ap_getbitbc: ;doubles BC and adds the read bit
+	sla c
+	rl b
+	call ap_getbit
+	ret z
+	inc bc
+	ret
+
+ap_getgamma:
+	ld bc,1
+ap_getgammaloop:
+	call ap_getbitbc
+	call ap_getbit
+	jr nz,ap_getgammaloop
+	ret
+
+
+depack:
+	;hl = source
+	;de = dest
+	ldi
+	xor a
+	ld (lwm),a
+	inc a
+	ld (ap_bits),a
+	
+aploop:
+	call ap_getbit
+	jp z, apbranch1
+	call ap_getbit
+	jr z, apbranch2
+	call ap_getbit
+	jr z, apbranch3
+	;LWM = 0
+	xor a
+	ld (lwm),a
+	;get an offset
+	ld bc,0
+	call ap_getbitbc
+	call ap_getbitbc
+	call ap_getbitbc
+	call ap_getbitbc
+	ld a,b
+	or c
+	jr nz,apbranch4
+	xor a  ;write a 0
+	ld (de),a
+	inc de
+	jr aploop
+apbranch4:
+	ex de,hl ;write a previous bit (1-15 away from dest)
+	push hl
+		sbc hl,bc
+		ld a,(hl)
+	pop hl
+	ld (hl),a
+	inc hl
+	ex de,hl
+	jr aploop
+apbranch3:
+	;use 7 bit offset, length = 2 or 3
+	;if a zero is encountered here, it's EOF
+	ld c,(hl)
+	inc hl
+	rr c
+	ret z
+	ld b,2
+	jr nc,ap_dont_inc_b
+	inc b
+ap_dont_inc_b:
+	;LWM = 1
+	ld a,1
+	ld (lwm),a
+	
+	push hl
+		ld a,b
+		ld b,0
+		;R0 = c
+		ld (r0),bc
+		ld h,d
+		ld l,e
+		or a
+		sbc hl,bc
+		ld c,a
+		ldir
+	pop hl
+	jr aploop
+apbranch2:
+	;use a gamma code * 256 for offset, another gamma code for length
+	call ap_getgamma
+	dec bc
+	dec bc
+	ld a,(lwm)
+	or a
+	jr nz,ap_not_lwm
+	;bc = 2?
+	ld a,b
+	or c
+	jr nz,ap_not_zero_gamma
+	;if gamma code is 2, use old r0 offset, and a new gamma code for length
+	call ap_getgamma
+	push hl
+		ld h,d
+		ld l,e
+		push bc
+			ld bc,(r0)
+			sbc hl,bc
+		pop bc
+		ldir
+	pop hl
+	jr ap_finishup
+	
+ap_not_zero_gamma:
+	dec bc
+ap_not_lwm:
+	;do I even need this code?
+	;bc=bc*256+(hl), lazy 16bit way
+	ld b,c
+	ld c,(hl)
+	inc hl
+	ld (r0),bc
+	push bc
+		call ap_getgamma
+		ex (sp),hl
+		;bc = len, hl=offs
+		push de
+			ex de,hl
+			;some comparison junk for some reason
+			ld hl,31999
+			or a
+			sbc hl,de
+			jr nc,skip1
+			inc bc
+skip1:
+			ld hl,1279
+			or a
+			sbc hl,de
+			jr nc,skip2
+			inc bc
+skip2:
+			ld hl,127
+			or a
+			sbc hl,de
+			jr c,skip3
+			inc bc
+			inc bc
+skip3:
+			;bc = len, de = offs, hl=junk
+		pop hl
+		push hl
+			or a
+			sbc hl,de
+		pop de
+		;hl=dest-offs, bc=len, de = dest
+		ldir
+	pop hl
+ap_finishup:
+	ld a,1
+	ld (lwm),a
+	jp aploop
+
+apbranch1:
+	ldi
+	xor a
+	ld (lwm),a
+	jp aploop
-- 
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