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- | TIGCC Program Starter - Shrink92 decompression support
- | SHRINK92 - Copyright 1998, 1999 David Kuehling
- | Adaptation for TI-89/92+ - Copyright 2002, 2003, 2004, 2005 Patrick Pelissier
- | Adaptation for pstarter - Copyright 2005 Kevin Kofler
- | Additional Optimizations - By Samuel Stearley
- |
- | This file is based on the SHRINK92 Library.
- |
- | The SHRINK92 Library is free software; you can redistribute it and/or modify
- | it under the terms of the GNU Lesser General Public License as published by
- | the Free Software Foundation; either version 2.1 of the License, or (at your
- | option) any later version.
- |
- | The SHRINK92 Library is distributed in the hope that it will be useful, but
- | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
- | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
- | License for more details.
- |
- | You should have received a copy of the GNU Lesser General Public License
- | along with the SHRINK92 Library; see the file COPYING.LIB. If not, write to
- | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
- | MA 02111-1307, USA.
- | Version : 1.00.P4-tigcc-2 by Kevin Kofler Apr 23 2005
- | * adjust calling convention for pstarter changes
- | Version : 1.00.P4-tigcc-1 by Kevin Kofler Mar 18 2005
- | * change tios.h to doorsos.h
- | * delete TI-92 support
- | * delete archive pack support
- | * allocate Table of Unresolved Elements on the stack
- | * use HeapAllocPtr to allocate archive descriptor
- | * throw an error if allocating the archive descriptor fails
- | * don't allocate memory in Extract
- | * free archive descriptor at end of Extract, delete CloseArchive
- | * always extract first section
- | * read uncompressed size in OpenArchive
- | * adjust calling conventions for pstarter
- | * use nostub ROM_CALL convention
- | * convert to GNU as
- | Version : 1.00.P4 by Patrick Pelissier Feb 10 2005
- | Version : 1.00.P3 by Patrick Pelissier Nov 10 2004
- | Version : 1.00.P2 by Patrick Pelissier Nov 24 2003
- .equ RLE_ESC,256
- .equ RLE_BITS,5
- .equ REP_ESC,257
- .equ START_REP_BITS,4
- .equ START_REP_CODES,16
- .equ REP_CODES,64
- .equ MIN_REP,3
- .equ CODES,256+REP_CODES+1
- | GET_UNCOMPRESSED_SIZE inline function
- | INPUT: %a3.l: pointer to compressed data
- | OUTPUT: %d6.l: uncompressed size
- | SIDE EFFECTS: throws a Data Type error if not a valid compressed program
- | may throw a Memory error
- | may advance %a3 for later decompression
- | DESTROYS: %d0-%d2/%a0-%a1
- .macro GET_UNCOMPRESSED_SIZE
- | Get the length of the variable.
- moveq.l #0,%d6
- move.w (%a3)+,%d6
- | Get a pointer to the data type of the variable.
- lea.l -1(%a3,%d6.l),%a0
- | Check if it has type "SHRN".
- cmp.b #0xf8,(%a0)
- jbne invalid_archive
- tst.b -(%a0)
- jbne invalid_archive
- cmp.b #'N',-(%a0)
- jbne invalid_archive
- cmp.b #'R',-(%a0)
- jbne invalid_archive
- cmp.b #'H',-(%a0)
- jbne invalid_archive
- cmp.b #'S',-(%a0)
- jbne invalid_archive
- tst.b -(%a0)
- jbeq valid_archive
- invalid_archive:
- .word 0xA000+210 | ER_DATATYPE
- valid_archive:
- bsr OpenArchive
- .endm
- | MEM_TO_MEM_DECOMPRESS inline function
- | INPUT: %a3.l: pointer to compressed data
- | %a0.l: pointer to buffer for uncompressed data
- | %d6.l: uncompressed size
- | OUTPUT: %a4.l: pointer to uncompressed data
- | SIDE EFFECTS: may throw a Memory or Data Type error
- | DESTROYS: %d0-%d2/%a0-%a2
- .macro MEM_TO_MEM_DECOMPRESS
- bsr Extract
- .endm
- || **************************************************************************
- | OpenArchive
- | --------------------------------------------------------------------------
- | Input: %a3.l = pointer to archive
- | Output: %a3.l = pointer to archive descriptor
- | %d6.l = length of section
- | Destroys: %d1-%d2/%a0-%a1
- | Throws ER_MEMORY if not enough memory.
- | /
- OpenArchive: movem.l %d0/%d3-%d5/%d7/%a2/%a4/%a6,-(%a7)
- movea.l %a7,%a6 | %a6 = saved SP for removing stack arguments later
- movea.l %a3,%a2 | %a2 = pointer to archive (%a2 isn't modified by ROM functions)
- || ***** Initialize The Table Of The Unresolved Leaves/Junctions| /
- | Table's format: <weight (word)> <address (word)> ...
- | <address>: pointer,relative to the huffman tree's begin
- | if the MSB is set: it represents a compression CODE (character)
- | /
- || allocate memory for the table| /
- lea -(CODES*4)(%a7),%a7
- movea.l %a7,%a3
-
- || uncompress frequency table from archive's begin into that table| /
- | %a2 = pointer to archive begin (RLE compressed freqency table| each byte is a frequency) -- input
- | %a3 = pointer to Unresolved Table -- output
- move.w #0x8000,%d7 | %d7 = <address>-counter (code | 0x8000)
- movea.l %a3,%a1 | %a1 = output-pointer (is increased whereas %a3 points to the table's begin)
- clr.w %d1 | %d1.w = one byte (high byte has to be cleared)
- moveq #-1,%d3 | %d3.w = number of entries in table - 1
- OAExtrFreqLoop: clr.w %d0 | %d0 = RLE repetition length - 1 (0 = ONE character -- no RLE)
- move.b (%a2)+,%d1 | %d1 = current byte / RLE ESC byte
- cmpi.w #0xE0,%d1 | is it an RLE ESC character ?
- blt.s OA__RLEloop | (if it isn't: cylcle one time through RLE loop)
- andi.w #0x001F,%d1 | extract RLE length from RLE ESC byte
- move.w %d1,%d0
- move.b (%a2)+,%d1 | read RLE byte
- OA__RLEloop: tst.w %d1 | don't add entries with a frequency of zero
- beq.s OA____Skip
- move.w %d1,(%a1)+ | copy frequency and <address> (%d7) to output table (%a1)
- move.w %d7,(%a1)+
- addq.w #1,%d3 | (%d3 = number of table entries)
- OA____Skip: addq.w #1,%d7
- dbra %d0,OA__RLEloop
- cmpi.w #CODES+0x8000,%d7
- blt.s OAExtrFreqLoop
- || align input address on even address| /
- move.l %a2,%d1
- addq.l #1,%d1
- bclr.b #0,%d1
- movea.l %d1,%a2
- || ***** Create Archive Descriptor,Containing the Huffman Tree| /
- | %d3 = number of entries in Table of Unresolved Elements - 1
- | %a2 = aligned pointer directly after the RLE compressed frequency table in the input archive
- | %a3 = pointer to first entry in Table of Unresolved Elements
- || allocate memory for archive descriptor| /
- move.w (%a2)+,-(%a7) | at the current position in the archive the size of the descriptor is stored
- clr.w -(%a7) | it is a long value
- move.l 0xa2*4(%a5),%a0 | HeapAllocPtr
- jsr (%a0)
- move.l %a0,%d5 | %a0 = %d5 = pointer to archive descriptor
- beq.s OAError
- move.l %a2,(%a0)+ | store archive address into descriptor
- movea.l %a0,%a1 | %a1 = working pointer| %a0 = pointer to huffman tree
- clr.w (%a1)+ | leave space for root pointer
- moveq #0,%d6 | extend 2(%a2) to longword in %d6
- move.w 2(%a2),%d6 | %d6 = length of section
- || create the huffman tree| /
- OAHuffTreeLoop: || find the two elements with the lowest weight| /
- bsr.s OAGetMinWeight | %a2 = pointer to min element| %d0 = its weight
- move.w %d0,%d2 | %d2 = lowest weight 1
- move.w 2(%a2),%d4 | %d4 = relative pointer to lowest elm 1
- move.l (%a3)+,(%a2) | "delete" element from unresolved list (replace it by first elm)
- subq.w #1,%d3 | decrease number of entries
- bmi.s OAHuffTreeEnd | if number of entries was #1: end of Huffman Tree creation
- bsr.s OAGetMinWeight | %a2 = pointer to min element| %d0 = it's weight
-
- || replace that element by a newly created junction of the two min elements| /
- | %d2 = lowest weight1
- | %d4 = relative pointer to lowest elm 1
- | %a2 = pointer to entry of loweset elm1 in unresolved table: (%a2) = weight| 2(%a2) = pointer
- add.w %d2,(%a2)+ | weight of min2 += weight of min1
- move.l %a1,%d1 | %d1 = relative address of new junction
- sub.l %a0,%d1
- move.w %d4,(%a1)+ | new Huffman Tree element: set left branch of junction
- move.w (%a2),(%a1)+ | set right branch of junction
- move.w %d1,(%a2) | entry in Unresolved Table: set the pointer to the Huffman Tree element
- bra.s OAHuffTreeLoop | continue...
-
- OAHuffTreeEnd: move.w %d4,(%a0) | store root pointer to archive descriptor
- movea.l %d5,%a3 | %a3 = pointer to archive descriptor
- movea.l %a6,%a7 | restore stored %a7 -- remove all stack elements
- movem.l (%a7)+,%d0/%d3-%d5/%d7/%a2/%a4/%a6 | restore registers
- rts
- OAError:
- .word 0xa000+670 |ER_MEMORY
- |
- | Get the element witht the minimum weight in the table of unresolved tree elements.
- | Input: %a3 = pointer to first table entry
- | %d3 = number of entries - 1
- | Output: %a2 = pointer to element with the minimum weight < 32767 or NULL if no such elements are left
- | %d0 = minimum weight
- | %a4/%d1 destroyed!
- | /
- OAGetMinWeight: moveq #-1,%d0 | %d0 = minimum weight = 32768 (unsigned)
- move.w %d3,%d1 | %d1 = counter
- movea.l %a3,%a4 | %a4 = scanning pointer
- OACmpLoop: cmp.w (%a4),%d0 | current element's weight less than minimum weight ?
- bls.s OA__NotLess
- movea.l %a4,%a2 | minimum element found: update %a2 and %d0
- move.w (%a4),%d0
- OA__NotLess: addq.l #4,%a4 | go to next element
- dbra %d1,OACmpLoop
- rts
- || *************************************************************************************************
- | Bitwise Input
- | /
- || *************************************************************************************************
- | ReadBit
- | --------------------------------------------------------------------------------------------------
- | Input: %a2.l = pointer to next byte
- | %d0.b = contents of current byte
- | %d1.b = last bit number
- | Output: zeroflag set or cleared,depending on value of bit,
- | %a2,%d0,%d1 adjusted to current bit
- | /
- ReadBit:
- subq.b #1,%d1 | increase bit number -- go to current bit
- bne.s RBSameByte
- move.b (%a2)+,%d0 | read new byte,begin again with bit #0
- moveq #8,%d1
- RBSameByte: lsr.b #1,%d0 | test bit -- set carry/extend flag accordingly
- rts
- || *************************************************************************************************
- | ReadNBits
- | --------------------------------------------------------------------------------------------------
- | Input: %a2.l = pointer to next byte
- | %d0.b = contents of current byte
- | %d1.b = last bit number
- | %d7.w = number of bits to read
- | Output: %a2,%d0,%d1 adjusted to last bit of bits read
- | %d7 = -1
- | %d3 = read bits (first read bit is high bit)
- | /
- ReadNBits: subq.w #1,%d7 | %d7 = counter
- moveq #0,%d3 | %d3 = bits
- RNBReadLoop: bsr.s ReadBit | read a bit
- addx.l %d3,%d3 | move in the bit
- RNB__ZeroBit: dbra %d7,RNBReadLoop
- rts
-
- || *************************************************************************************************
- | Extract
- | --------------------------------------------------------------------------------------------------
- | Input: %a3.l = pointer to archive descriptor
- | %a0.l = address of extraction destination
- | %d6.l = length of section
- | Output: %a4.l = address of extraction destination
- | Throws ER_DATATYPE for an invalid archive.
- | Destroys: %d0-%d2/%a0-%a2
- | /
- Extract: movem.l %d3-%d7/%a3/%a6,-(%a7)
- || Prepare Extraction...| /
- move.l (%a3),%a2 | %a2 = pointer to archive data (after frequency table)
- adda.w (%a2),%a2 | %a2 = address of first section (expect offset <32768)
- |SNS changed it to a 1
- moveq #1,%d1 | %d1 = bit number (1 forces 'ReadBit' to read new byte into %d0)
- moveq #0,%d4 | %d4 = input offset
- movea.l %a0,%a1 | %a1 = working destination pointer
- | %a0 = address of destination memory block
- | %a1 = address of destination memory block (working pointer that is increased during extraction)
- | %a2 = address of archive section begin (is increased during extraction)
- | %a3 = pointer to huffman tree begin (within descriptor)
- | %d0 = current byte
- | %d1 = bit number within current byte '%d0'
- | %d2 = handle of allocated destination block or original value
- | %d6 = length of section
- | %d4 = current input offset
- || ***** Extraction Loop| /
- EXExtractLoop:
- || check whether end of file| /
- cmp.l %d6,%d4
- beq.s EXExtractEnd
- bgt.s EXError
-
- || read a Huffman code| /
- moveq #0,%d7
- EX__HuffLoop: move.w 4(%a3, %d7.w),%d7| %d7 = relative pointer to root element
- | if bit #15 in "address" is set -> it is a leaf| %d7 contains the code
- bmi.s EX__HuffDone | %d7 points to current element| (%d7) = left branch 2(%d7) = right branch
- bsr.s ReadBit
- bcc.s EX__HuffLoop
- addq.w #2,%d7 | continue with right branch
- bra.s EX__HuffLoop
- |SNS: unlike the previous version it has not yet cleared the high bit of d7
- EX__HuffDone: | %d7.w = current code
- cmp.w #256+32768,%d7 | check code
- beq.s EX__RLE | code = 256: RLE
- bgt.s EX__Rep | code > 256: Rep
- || 'code' (%d7) is a character| /
- move.b %d7,(%a1)+ | copy code to destination
- addq.l #1,%d4
- bra.s EXExtractLoop
- || RLE| /
- EX__RLE: move.b -1(%a1),%d5 | %d5 = RLE repeating character
- moveq #RLE_BITS,%d7 | read length of RLE sequence
- bsr ReadNBits
- addq.w #1,%d3 | %d3 = RLE repetition length - 1
- add.l %d3,%d4
- addq.l #1,%d4
- EX____RLEloop: move.b %d5,(%a1)+ | output characters...
- dbra %d3,EX____RLEloop
- bra.s EXExtractLoop
- || Repetition encoding| /
- EX__Rep: sub.w #32768+REP_ESC-MIN_REP+1,%d7 | %d7 = length of repetition - 1
- move.w %d7,-(%a7) | store it on the stack
- moveq #START_REP_BITS-1,%d7 | get the number of bits that is required for coding an offset
- moveq #START_REP_CODES/2,%d3
- EX____IncrBitN: addq.l #1,%d7
- add.l %d3,%d3
- move.l %d3,%d5
- addq.l #MIN_REP,%d5
- cmp.l %d4,%d5 | codable range is too small ? --> increase bit number and try again
- bls.s EX____IncrBitN
- | %d7 = number of bits
- bsr ReadNBits | %d3 = repetition offset
- move.w (%a7)+,%d7 | %d7 = length of repetition - 1
- lea 0(%a0,%d3.l),%a4 | %a4 = pointer to repetition
- add.l %d7,%d4
- addq.l #1,%d4
- EX____RepCopyLp: move.b (%a4)+,(%a1)+ | copy repetition to current output position...
- dbra %d7,EX____RepCopyLp
- bra.s EXExtractLoop
- EXError: suba.l %a0,%a0 | %a0 = zero (indicates error)
- EXExtractEnd: movea.l %a0,%a4
- pea.l (%a3) | Free Archive Descriptor
- move.l 0xa3*4(%a5),%a0 | HeapFreePtr
- jsr (%a0)
- addq.l #4,%a7
- move.l %a4,%d0
- beq invalid_archive
- movem.l (%a7)+,%d3-%d7/%a3/%a6
- rts
|