| 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:
... |
: 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 =
-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
(%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