Extra libs: ap.lib

aPLib support with apultra.

1 files changed, 258 insertions, 0 deletions

diff --git a/tools/apultra/asm/Z80/unaplib_small.asm b/tools/apultra/asm/Z80/unaplib_small.asm
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+;

+;  Size-optimized ApLib decompressor by spke & uniabis (ver.04 01-07/06/2020, 139 bytes)

+;

+;  The original Z80 decompressor for ApLib was written by Dan Weiss (Dwedit),

+;  then tweaked by Francisco Javier Pena Pareja (utopian),

+;  and optimized by Jaime Tejedor Gomez (Metalbrain).

+;

+;  This version was heavily re-optimized for size by spke.

+;  (It is 17 bytes shorter and 22% faster than the 156b version by Metalbrain.)

+;

+;  ver.00 by spke (21/08/2018-01/09/2018, 141 bytes);

+;  ver.01 by spke (spring 2019, 140(-1) bytes, slightly faster);

+;  ver.02 by spke (05-07/01/2020, added full revision history, support for long offsets

+;                  and an option to use self-modifying code instead of IY)

+;  ver.03 by spke (18-29/05/2020, +0.5% speed, added support for backward compression)

+;  ver.04 by uniabis (01-07/06/2020, 139(-1) bytes, +1% speed, added support for HD64180)

+;

+;  The data must be compressed using any compressor for ApLib capable of generating raw data.

+;  At present, two best available compressors are:

+;

+;  "APC" by Sven-Ake Dahl: https://github.com/svendahl/cap or

+;  "apultra" by Emmanuel Marty: https://github.com/emmanuel-marty/apultra

+;

+;  The compression can be done as follows:

+;

+;  apc.exe e <sourcefile> <outfile>

+;  or

+;  apultra.exe <sourcefile> <outfile>

+;

+;  A decent compressor was written by r57shell (although it is worse than compressors above):

+;  http://gendev.spritesmind.net/forum/viewtopic.php?p=32548#p32548

+;  The use of the official ApLib compressor by Joergen Ibsen is not recommended.

+;

+;  The decompression is done in the standard way:

+;

+;  ld hl,FirstByteOfCompressedData

+;  ld de,FirstByteOfMemoryForDecompressedData

+;  call DecompressApLib

+;

+;  Backward decompression is also supported; you can compress files backward using:

+;

+;  apultra.exe -b <sourcefile> <outfile>

+;

+;  uncomment option "DEFINE BackwardDecompression" and decompress the resulting files using:

+;

+;  ld hl,LastByteOfCompressedData

+;  ld de,LastByteOfMemoryForDecompressedData

+;  call DecompressApLib

+;

+;  The decompressor modifies AF, AF', BC, DE, HL, IX.

+;

+;  Of course, ApLib compression algorithms are (c) 1998-2014 Joergen Ibsen,

+;  see http://www.ibsensoftware.com/ for more information

+;

+;  Drop me an email if you have any comments/ideas/suggestions: zxintrospec@gmail.com

+;

+;  This software is provided 'as-is', without any express or implied

+;  warranty.  In no event will the authors be held liable for any damages

+;  arising from the use of this software.

+;

+;  Permission is granted to anyone to use this software for any purpose,

+;  including commercial applications, and to alter it and redistribute it

+;  freely, subject to the following restrictions:

+;

+;  1. The origin of this software must not be misrepresented; you must not

+;     claim that you wrote the original software. If you use this software

+;     in a product, an acknowledgment in the product documentation would be

+;     appreciated but is not required.

+;  2. Altered source versions must be plainly marked as such, and must not be

+;     misrepresented as being the original software.

+;  3. This notice may not be removed or altered from any source distribution.

+

+;	DEFINE FasterGetBit					; 16% speed-up at the cost of extra 4 bytes

+;	DEFINE SupportLongOffsets				; +4 bytes for long offset support. slows decompression down by 1%, but may be needed to decompress files >=32K

+;	DEFINE BackwardDecompression				; decompress data compressed backwards, -5 bytes, speeds decompression up by 3%

+

+

+	IFDEF FasterGetBit

+		MACRO	GET_BIT

+			add a : call z,ReloadByte

+		ENDM

+	ELSE

+		MACRO	GET_BIT

+			call GetOneBit

+		ENDM

+	ENDIF

+

+	IFNDEF BackwardDecompression

+

+		MACRO NEXT_HL

+		inc hl

+		ENDM

+

+		MACRO COPY_1

+		ldi

+		ENDM

+

+		MACRO COPY_BC

+		ldir

+		ENDM

+

+	ELSE

+

+		MACRO NEXT_HL

+		dec hl

+		ENDM

+

+		MACRO COPY_1

+		ldd

+		ENDM

+

+		MACRO COPY_BC

+		lddr

+		ENDM

+

+	ENDIF

+

+@DecompressApLib:	ld a,128

+

+;

+;  case "0"+BYTE: copy a single literal

+

+CASE0:			COPY_1					; first byte is always copied as literal

+ResetLWM:		ld b,-1					; LWM = 0 (LWM stands for "Last Was Match"; a flag that we did not have a match)

+

+;

+;  main decompressor loop

+

+MainLoop:		GET_BIT : jr nc,CASE0			; "0"+BYTE = copy literal

+			GET_BIT : jr nc,CASE10			; "10"+gamma(offset/256)+BYTE+gamma(length) = the main matching mechanism

+

+			ld bc,%11100000

+			GET_BIT : jr nc,CASE110			; "110"+[oooooool] = matched 2-3 bytes with a small offset

+

+;

+;  case "111"+"oooo": copy a byte with offset -1..-15, or write zero to dest

+

+CASE111:

+ReadFourBits		GET_BIT					; read short offset (4 bits)

+			rl c : jr c,ReadFourBits

+			ex de,hl : jr z,WriteZero		; zero offset means "write zero" (NB: B is zero here)

+

+			; "write a previous byte (1-15 away from dest)"

+			push hl					; BC = offset, DE = src, HL = dest

+	IFNDEF BackwardDecompression

+			sbc hl,bc				; HL = dest-offset (SBC works because branching above ensured NC)

+	ELSE

+			add hl,bc				; HL = dest-offset (SBC works because branching above ensured NC)

+	ENDIF

+			ld c,(hl) : pop hl

+

+WriteZero		ld (hl),c : NEXT_HL

+			ex de,hl : jr ResetLWM			; write one byte, reset LWM

+

+;

+;  branch "110"+[oooooool]: copy two or three bytes (bit "l") with the offset -1..-127 (bits "ooooooo"), or stop

+

+CASE110:		; "use 7 bit offset, length = 2 or 3"

+			; "if a zero is found here, it's EOF"

+			ld c,(hl) : rr c : ret z		; process EOF

+			NEXT_HL

+

+			push hl					; save src

+			ld h,b : ld l,c				; HL = offset

+

+			; flag NC means len=2, flag C means len=3

+			ld c,1 : rl c : jr SaveLWMOffset

+			

+;

+;  branch "10"+gamma(offset/256)+BYTE+gamma(length): the main matching mechanism

+

+CASE10:			; save state of LWM into A'

+			exa : ld a,b : exa

+

+			; "use a gamma code * 256 for offset, another gamma code for length"

+			call GetGammaCoded

+

+			; the original decompressor contains

+			;

+			; if ((LWM == 0) && (offs == 2)) { ... }

+			; else {

+			;	if (LWM == 0) { offs -= 3; }

+			;	else { offs -= 2; }

+			; }

+			;

+			; so, the idea here is to use the fact that GetGammaCoded returns (offset/256)+2,

+			; and to split the first condition by noticing that C-1 can never be zero

+			exa : add c : ld c,a : exa

+

+			; "if gamma code is 2, use old r0 offset"

+			dec c : jr z,KickInLWM

+			dec c

+			ld b,c : ld c,(hl) : NEXT_HL		; BC = offset

+

+			push bc					; (SP) = offset

+			call GetGammaCoded			; BC = len*

+			ex (sp),hl				; HL = offset, (SP) = src

+

+			; interpretation of length value is offset-dependent

+			exa : ld a,h

+	IFDEF	SupportLongOffsets

+			; NB offsets over 32000 require an additional check, which is skipped in most

+			; Z80 decompressors (seemingly as a performance optimization)

+			cp 32000/256 : jr nc,.Add2

+	ENDIF

+			cp 5 : jr nc,.Add1

+			or a : jr nz,.Add0

+			bit 7,l : jr nz,.Add0

+.Add2			inc bc

+.Add1			inc bc

+.Add0			exa

+

+SaveLWMOffset:

+			push hl : pop ix			; save offset for future LWMs

+

+CopyMatch:		; this assumes that BC = len, DE = dest, HL = offset

+			; and also that (SP) = src, while having NC

+	IFNDEF BackwardDecompression

+			push de

+			ex de,hl : sbc hl,de			; HL = dest-offset

+			pop de					; DE = dest

+	ELSE

+			add hl,de				; HL = dest+offset

+	ENDIF

+

+			COPY_BC

+			pop hl					; recover src

+			jr MainLoop

+

+;

+;  the re-use of the previous offset (LWM magic)

+

+KickInLWM:		; "and a new gamma code for length"

+			call GetGammaCoded			; BC = len

+			push ix : ex (sp),hl			; DE = dest, HL = prev offset

+			jr CopyMatch

+

+;

+;  interlaced gamma code reader

+;  x0 -> 1x

+;  x1y0 -> 1xy

+;  x1y1z0 -> 1xyz etc

+;  (technically, this is a 2-based variation of Exp-Golomb-1)

+

+GetGammaCoded:		ld bc,1

+ReadGamma		GET_BIT : rl c : rl b

+			GET_BIT : ret nc

+			jr ReadGamma

+

+;

+;  pretty usual getbit for mixed datastreams

+

+	IFNDEF FasterGetBit

+GetOneBit:		add a : ret nz

+	ENDIF

+ReloadByte:		ld a,(hl) : NEXT_HL

+			rla : ret

+