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authorJuan J. Martinez <jjm@usebox.net>2020-12-30 19:07:31 +0000
committerJuan J. Martinez <jjm@usebox.net>2020-12-30 19:23:41 +0000
commit2682bc5d1d864341aaeb42a449db73c3ecd16d70 (patch)
tree9116764364b4ee0ce7f6037305077807b57776de /tools/rasm/decrunch/aplib_z80_todo.asm
downloadubox-msx-lib-2682bc5d1d864341aaeb42a449db73c3ecd16d70.tar.gz
ubox-msx-lib-2682bc5d1d864341aaeb42a449db73c3ecd16d70.zip
Initial import1.0
Diffstat (limited to 'tools/rasm/decrunch/aplib_z80_todo.asm')
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1 files changed, 190 insertions, 0 deletions
diff --git a/tools/rasm/decrunch/aplib_z80_todo.asm b/tools/rasm/decrunch/aplib_z80_todo.asm
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+;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