Z80 Routines:Other:IonCompress - Revision history

Dan Englender: Added untested code template. I probably messed something up. Feel free to fix

2006-04-07T15:01:42Z

Added untested code template. I probably messed something up. Feel free to fix

Saibot84: trying to add the category...crude special thanks...

2006-04-07T04:08:40Z

trying to add the category...crude special thanks...

Saibot84: untested ioncompress routine

2006-04-07T04:01:47Z

untested ioncompress routine

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<nowiki>;Ion Compression Routines
;These routines are <supposed to> compress data in the format used by
;the IonDecompress routine. I, Saibot84, have only reverse-engineered
;the compression algorithm based on the IonDecompress routine.
;
;Just a note: The way I consider this, there is a routine that does
;the work, and then there may be a routine that modifies slightly the
;inputs and outputs of the first routine. This modifying routine, I
;call the MetaLibrary routine as an analogy to how physics is under
;metaphysics. ;-)
;
;I know it's not good to post untested bits of code, but I just
;stumbled upon this on my computer and remembered I wanted to
;release it.
;
;IonCompress
;Inputs:
; hl->where to read the data from
; de->where to store the compressed output
; b = number of bytes to copmpress
; c = compression factor (see IonDecompress)
;Outputs:
; hl->end of where to read
; de->end of where to store
; carry flag: set->error res->all is well
;
;MetaLib_IonCompress
;Inputs:
; hl->where to read the data from
; de->where to store the compressed output
; bc = number of bytes to copmpress
; a = compression factor (see IonDecompress)
;Outputs:
; hl->end of where to read
; de->end of where to store
; bc = new length
; carry flag: set->error res->all is well

IonCompress:
;016-7-2005
;=>hl->read
;=>de->sto
;=>b=len
;=>c=comp factor
;<=hl->read+len
;<=de->sto+len(new)
;<=cf=error
ld a,c
cp 2
jr nc, IC_Next1
srl b
IC_Next1:
cp 4
jr nc,IC_Next2
srl b
IC_Next2:
srl b
push ix
IC_Loop:
push bc
ld ixh,0
ld ixl,8
ld a,c
ld b,8
cp 1
jr z,IC_cmp1
ld b,4
cp 3
jr z,IC_cmp1
ld b,2
IC_cmp1:
push bc
ld a,c
ld b,1
cp 1
jr z,IC_cmp2
inc b
cp 3
jr z,IC_cmp2
ld b,4
IC_cmp2:
ld a,ixl
sub b
ld b,a
ld ixl,a
ld a,c
cp (hl)
jr c,IC_Error
ld a,(hl)
IC_cmp3:
sla a
djnz IC_cmp3
or ixh
inc hl
pop bc
djnz IC_cmp1
inc de
pop bc
djnz IC_Loop
IC_Exit:
pop ix
ret
IC_Error:
pop bc
pop bc
jr IC_Exit

MetaLib_IonCompress:
;016-7-2005
;=>hl->read
;=>de->sto
;=>bc=len
;=>a=comp factor
;<=hl->read+len
;<=de->sto+len(new)
;<=bc=new length
;<=cf=error
push de
push af
push bc
ld b,a
ld a,c
or a
ld a,b
pop bc
jr z,ML_IC_Loop
inc b
ML_IC_Loop:
push bc
push af
ld b,c
ld c,a
call IonCompress
ret c
pop af
pop bc
ld c,0
djnz ML_IC_Loop
pop af
ex (sp),hl
ex de,hl
push hl
or a
sbc hl,de
pop de
push hl
pop bc
pop hl
ret</nowiki>

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 [[Category:Z80 Routines:Other|IonCompress]]
 [[Category:Z80 Routines|IonCompress]]
   <nowiki>;Ion Compression Routines
 ;These routines are <supposed to> compress data in the format used by