From 9fc9a49d672c0d7fd56a1d5e98300d664e2ba2bb Mon Sep 17 00:00:00 2001 From: Peter Ferrie Date: Thu, 31 Oct 2019 22:20:02 -0700 Subject: [PATCH] fast v1 --- asm/6502/decompress_fast_v1.asm | 303 ++++++++++ ...ompress_v1.asm => decompress_small_v1.asm} | 540 +++++++++--------- 2 files changed, 573 insertions(+), 270 deletions(-) create mode 100644 asm/6502/decompress_fast_v1.asm rename asm/6502/{decompress_v1.asm => decompress_small_v1.asm} (96%) mode change 100755 => 100644 diff --git a/asm/6502/decompress_fast_v1.asm b/asm/6502/decompress_fast_v1.asm new file mode 100644 index 0000000..2c58150 --- /dev/null +++ b/asm/6502/decompress_fast_v1.asm @@ -0,0 +1,303 @@ +; ----------------------------------------------------------------------------- +; Decompress raw LZSA1 block. Create one with lzsa -r +; +; in: +; * LZSA_SRC_LO and LZSA_SRC_HI contain the compressed raw block address +; * LZSA_DST_LO and LZSA_DST_HI contain the destination buffer address +; +; out: +; * LZSA_DST_LO and LZSA_DST_HI contain the last decompressed byte address, +1 +; +; ----------------------------------------------------------------------------- +; Backward decompression is also supported, use lzsa -r -b +; To use it, also define BACKWARD_DECOMPRESS=1 before including this code! +; +; in: +; * LZSA_SRC_LO/LZSA_SRC_HI must contain the address of the last byte of compressed data +; * LZSA_DST_LO/LZSA_DST_HI must contain the address of the last byte of the destination buffer +; +; out: +; * LZSA_DST_LO/LZSA_DST_HI contain the last decompressed byte address, -1 +; +; ----------------------------------------------------------------------------- +; +; Copyright (C) 2019 Emmanuel Marty, Peter Ferrie +; +; 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. +; ----------------------------------------------------------------------------- + +DECOMPRESS_LZSA1_FAST + LDY #$00 + +DECODE_TOKEN + JSR GETSRC ; read token byte: O|LLL|MMMM + PHA ; preserve token on stack + + AND #$70 ; isolate literals count + BEQ NO_LITERALS ; skip if no literals to copy + CMP #$70 ; LITERALS_RUN_LEN? + BNE PREPARE_COPY_LITERALS ; if not, count is directly embedded in token + + JSR GETSRC ; get extra byte of variable literals count + ; the carry is always set by the CMP above + ; GETSRC doesn't change it + SBC #$F9 ; (LITERALS_RUN_LEN) + BCC PREPARE_COPY_LITERALS_DIRECT + BEQ LARGE_VARLEN_LITERALS ; if adding up to zero, go grab 16-bit count + + JSR GETSRC ; get single extended byte of variable literals count + INY ; add 256 to literals count + BCS PREPARE_COPY_LITERALS_DIRECT ; (*like JMP PREPARE_COPY_LITERALS_DIRECT but shorter) + +LARGE_VARLEN_LITERALS ; handle 16 bits literals count + ; literals count = directly these 16 bits + JSR GETLARGESRC ; grab low 8 bits in X, high 8 bits in A + TAY ; put high 8 bits in Y + TXA + JMP PREPARE_COPY_LARGE_LITERALS + +PREPARE_COPY_LITERALS + TAX + LDA SHIFT_TABLE-1,X ; shift literals length into place + ; -1 because position 00 is reserved + TAX + +PREPARE_COPY_LARGE_LITERALS + BEQ COPY_LITERALS + INY + +COPY_LITERALS + JSR GETPUT ; copy one byte of literals + DEX + BNE COPY_LITERALS + DEY + BNE COPY_LITERALS + +NO_LITERALS + PLA ; retrieve token from stack + PHA ; preserve token again + BMI GET_LONG_OFFSET ; $80: 16 bit offset + + JSR GETSRC ; get 8 bit offset from stream in A + TAX ; save for later + LDA #$FF ; high 8 bits + BNE GOT_OFFSET ; go prepare match + ; (*like JMP GOT_OFFSET but shorter) + +SHORT_VARLEN_MATCHLEN + JSR GETSRC ; get single extended byte of variable match len + INY ; add 256 to match length + +PREPARE_COPY_MATCH + TAX +PREPARE_COPY_MATCH_Y + TXA + BEQ COPY_MATCH_LOOP + INY + +COPY_MATCH_LOOP + LDA $AAAA ; get one byte of backreference + JSR PUTDST ; copy to destination + +!ifdef BACKWARD_DECOMPRESS { + + ; Backward decompression -- put backreference bytes backward + + LDA COPY_MATCH_LOOP+1 + BEQ GETMATCH_ADJ_HI +GETMATCH_DONE + DEC COPY_MATCH_LOOP+1 + +} else { + + ; Forward decompression -- put backreference bytes forward + + INC COPY_MATCH_LOOP+1 + BEQ GETMATCH_ADJ_HI +GETMATCH_DONE + +} + + DEX + BNE COPY_MATCH_LOOP + DEY + BNE COPY_MATCH_LOOP + BEQ DECODE_TOKEN ; (*like JMP DECODE_TOKEN but shorter) + +!ifdef BACKWARD_DECOMPRESS { + +GETMATCH_ADJ_HI + DEC COPY_MATCH_LOOP+2 + JMP GETMATCH_DONE + +} else { + +GETMATCH_ADJ_HI + INC COPY_MATCH_LOOP+2 + JMP GETMATCH_DONE + +} + +GET_LONG_OFFSET ; handle 16 bit offset: + JSR GETLARGESRC ; grab low 8 bits in X, high 8 bits in A + +GOT_OFFSET + +!ifdef BACKWARD_DECOMPRESS { + + ; Backward decompression - substract match offset + + STA OFFSHI ; store high 8 bits of offset + STX OFFSLO + + SEC ; substract dest - match offset + LDA PUTDST+1 +OFFSLO = *+1 + SBC #$AA ; low 8 bits + STA COPY_MATCH_LOOP+1 ; store back reference address + LDA PUTDST+2 +OFFSHI = *+1 + SBC #$AA ; high 8 bits + STA COPY_MATCH_LOOP+2 ; store high 8 bits of address + SEC + +} else { + + ; Forward decompression - add match offset + + STA OFFSHI ; store high 8 bits of offset + TXA + + CLC ; add dest + match offset + ADC PUTDST+1 ; low 8 bits + STA COPY_MATCH_LOOP+1 ; store back reference address +OFFSHI = *+1 + LDA #$AA ; high 8 bits + + ADC PUTDST+2 + STA COPY_MATCH_LOOP+2 ; store high 8 bits of address + +} + + PLA ; retrieve token from stack again + AND #$0F ; isolate match len (MMMM) + ADC #$02 ; plus carry which is always set by the high ADC + CMP #$12 ; MATCH_RUN_LEN? + BCC PREPARE_COPY_MATCH ; if not, count is directly embedded in token + + JSR GETSRC ; get extra byte of variable match length + ; the carry is always set by the CMP above + ; GETSRC doesn't change it + SBC #$EE ; add MATCH_RUN_LEN and MIN_MATCH_SIZE to match length + BCC PREPARE_COPY_MATCH + BNE SHORT_VARLEN_MATCHLEN + + ; Handle 16 bits match length + JSR GETLARGESRC ; grab low 8 bits in X, high 8 bits in A + TAY ; put high 8 bits in Y + ; large match length with zero high byte? + BNE PREPARE_COPY_MATCH_Y ; if not, continue + +DECOMPRESSION_DONE + RTS + +SHIFT_TABLE + DB 00h,00h,00h,00h,00h,00h,00h,00h,00h,00h,00h,00h,00h,00h,00h + DB 01h,01h,01h,01h,01h,01h,01h,01h,01h,01h,01h,01h,01h,01h,01h,01h + DB 02h,02h,02h,02h,02h,02h,02h,02h,02h,02h,02h,02h,02h,02h,02h,02h + DB 03h,03h,03h,03h,03h,03h,03h,03h,03h,03h,03h,03h,03h,03h,03h,03h + DB 04h,04h,04h,04h,04h,04h,04h,04h,04h,04h,04h,04h,04h,04h,04h,04h + DB 05h,05h,05h,05h,05h,05h,05h,05h,05h,05h,05h,05h,05h,05h,05h,05h + DB 06h,06h,06h,06h,06h,06h,06h,06h,06h,06h,06h,06h,06h,06h,06h,06h + DB 07h,07h,07h,07h,07h,07h,07h,07h,07h,07h,07h,07h,07h,07h,07h,07h + +!ifdef BACKWARD_DECOMPRESS { + + ; Backward decompression -- get and put bytes backward + +GETPUT + JSR GETSRC +PUTDST +LZSA_DST_LO = *+1 +LZSA_DST_HI = *+2 + STA $AAAA + LDA PUTDST+1 + BEQ PUTDST_ADJ_HI +PUTDST_DONE + DEC PUTDST+1 + RTS + +PUTDST_ADJ_HI + DEC PUTDST+2 + JMP PUTDST_DONE + +GETLARGESRC + JSR GETSRC ; grab low 8 bits + TAX ; move to X + ; fall through grab high 8 bits + +GETSRC +LZSA_SRC_LO = *+1 +LZSA_SRC_HI = *+2 + LDA $AAAA + PHA + LDA GETSRC+1 + BEQ GETSRC_ADJ_HI +GETSRC_DONE + DEC GETSRC+1 + PLA + RTS + +GETSRC_ADJ_HI + DEC GETSRC+2 + JMP GETSRC_DONE + +} else { + + ; Forward decompression -- get and put bytes forward + +GETPUT + JSR GETSRC +PUTDST +LZSA_DST_LO = *+1 +LZSA_DST_HI = *+2 + STA $AAAA + INC PUTDST+1 + BEQ PUTDST_ADJ_HI + RTS + +PUTDST_ADJ_HI + INC PUTDST+2 + RTS + +GETLARGESRC + JSR GETSRC ; grab low 8 bits + TAX ; move to X + ; fall through grab high 8 bits + +GETSRC +LZSA_SRC_LO = *+1 +LZSA_SRC_HI = *+2 + LDA $AAAA + INC GETSRC+1 + BEQ GETSRC_ADJ_HI + RTS + +GETSRC_ADJ_HI + INC GETSRC+2 + RTS +} diff --git a/asm/6502/decompress_v1.asm b/asm/6502/decompress_small_v1.asm old mode 100755 new mode 100644 similarity index 96% rename from asm/6502/decompress_v1.asm rename to asm/6502/decompress_small_v1.asm index e49a595..ca4863b --- a/asm/6502/decompress_v1.asm +++ b/asm/6502/decompress_small_v1.asm @@ -1,270 +1,270 @@ -; ----------------------------------------------------------------------------- -; Decompress raw LZSA1 block. Create one with lzsa -r -; -; in: -; * LZSA_SRC_LO and LZSA_SRC_HI contain the compressed raw block address -; * LZSA_DST_LO and LZSA_DST_HI contain the destination buffer address -; -; out: -; * LZSA_DST_LO and LZSA_DST_HI contain the last decompressed byte address, +1 -; -; ----------------------------------------------------------------------------- -; Backward decompression is also supported, use lzsa -r -b -; To use it, also define BACKWARD_DECOMPRESS=1 before including this code! -; -; in: -; * LZSA_SRC_LO/LZSA_SRC_HI must contain the address of the last byte of compressed data -; * LZSA_DST_LO/LZSA_DST_HI must contain the address of the last byte of the destination buffer -; -; out: -; * LZSA_DST_LO/LZSA_DST_HI contain the last decompressed byte address, -1 -; -; ----------------------------------------------------------------------------- -; -; Copyright (C) 2019 Emmanuel Marty -; -; 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. -; ----------------------------------------------------------------------------- - -DECOMPRESS_LZSA1 - LDY #$00 - -DECODE_TOKEN - JSR GETSRC ; read token byte: O|LLL|MMMM - PHA ; preserve token on stack - - AND #$70 ; isolate literals count - BEQ NO_LITERALS ; skip if no literals to copy - LSR ; shift literals count into place - LSR - LSR - LSR - CMP #$07 ; LITERALS_RUN_LEN? - BCC PREPARE_COPY_LITERALS ; if not, count is directly embedded in token - - JSR GETSRC ; get extra byte of variable literals count - ; the carry is always set by the CMP above - ; GETSRC doesn't change it - SBC #$F9 ; (LITERALS_RUN_LEN) - BCC PREPARE_COPY_LITERALS - BEQ LARGE_VARLEN_LITERALS ; if adding up to zero, go grab 16-bit count - - JSR GETSRC ; get single extended byte of variable literals count - INY ; add 256 to literals count - BCS PREPARE_COPY_LITERALS ; (*like JMP PREPARE_COPY_LITERALS but shorter) - -LARGE_VARLEN_LITERALS ; handle 16 bits literals count - ; literals count = directly these 16 bits - JSR GETLARGESRC ; grab low 8 bits in X, high 8 bits in A - TAY ; put high 8 bits in Y - TXA - -PREPARE_COPY_LITERALS - TAX - BEQ COPY_LITERALS - INY - -COPY_LITERALS - JSR GETPUT ; copy one byte of literals - DEX - BNE COPY_LITERALS - DEY - BNE COPY_LITERALS - -NO_LITERALS - PLA ; retrieve token from stack - PHA ; preserve token again - BMI GET_LONG_OFFSET ; $80: 16 bit offset - - JSR GETSRC ; get 8 bit offset from stream in A - TAX ; save for later - LDA #$FF ; high 8 bits - BNE GOT_OFFSET ; go prepare match - ; (*like JMP GOT_OFFSET but shorter) - -SHORT_VARLEN_MATCHLEN - JSR GETSRC ; get single extended byte of variable match len - INY ; add 256 to match length - -PREPARE_COPY_MATCH - TAX -PREPARE_COPY_MATCH_Y - TXA - BEQ COPY_MATCH_LOOP - INY - -COPY_MATCH_LOOP - LDA $AAAA ; get one byte of backreference - JSR PUTDST ; copy to destination - -!ifdef BACKWARD_DECOMPRESS { - - ; Backward decompression -- put backreference bytes backward - - LDA COPY_MATCH_LOOP+1 - BNE GETMATCH_DONE - DEC COPY_MATCH_LOOP+2 -GETMATCH_DONE - DEC COPY_MATCH_LOOP+1 - -} else { - - ; Forward decompression -- put backreference bytes forward - - INC COPY_MATCH_LOOP+1 - BNE GETMATCH_DONE - INC COPY_MATCH_LOOP+2 -GETMATCH_DONE - -} - - DEX - BNE COPY_MATCH_LOOP - DEY - BNE COPY_MATCH_LOOP - BEQ DECODE_TOKEN ; (*like JMP DECODE_TOKEN but shorter) - -GET_LONG_OFFSET ; handle 16 bit offset: - JSR GETLARGESRC ; grab low 8 bits in X, high 8 bits in A - -GOT_OFFSET - -!ifdef BACKWARD_DECOMPRESS { - - ; Backward decompression - substract match offset - - STA OFFSHI ; store high 8 bits of offset - STX OFFSLO - - SEC ; substract dest - match offset - LDA PUTDST+1 -OFFSLO = *+1 - SBC #$AA ; low 8 bits - STA COPY_MATCH_LOOP+1 ; store back reference address - LDA PUTDST+2 -OFFSHI = *+1 - SBC #$AA ; high 8 bits - STA COPY_MATCH_LOOP+2 ; store high 8 bits of address - SEC - -} else { - - ; Forward decompression - add match offset - - STA OFFSHI ; store high 8 bits of offset - TXA - - CLC ; add dest + match offset - ADC PUTDST+1 ; low 8 bits - STA COPY_MATCH_LOOP+1 ; store back reference address -OFFSHI = *+1 - LDA #$AA ; high 8 bits - - ADC PUTDST+2 - STA COPY_MATCH_LOOP+2 ; store high 8 bits of address - -} - - PLA ; retrieve token from stack again - AND #$0F ; isolate match len (MMMM) - ADC #$02 ; plus carry which is always set by the high ADC - CMP #$12 ; MATCH_RUN_LEN? - BCC PREPARE_COPY_MATCH ; if not, count is directly embedded in token - - JSR GETSRC ; get extra byte of variable match length - ; the carry is always set by the CMP above - ; GETSRC doesn't change it - SBC #$EE ; add MATCH_RUN_LEN and MIN_MATCH_SIZE to match length - BCC PREPARE_COPY_MATCH - BNE SHORT_VARLEN_MATCHLEN - - ; Handle 16 bits match length - JSR GETLARGESRC ; grab low 8 bits in X, high 8 bits in A - TAY ; put high 8 bits in Y - ; large match length with zero high byte? - BNE PREPARE_COPY_MATCH_Y ; if not, continue - -DECOMPRESSION_DONE - RTS - -!ifdef BACKWARD_DECOMPRESS { - - ; Backward decompression -- get and put bytes backward - -GETPUT - JSR GETSRC -PUTDST -LZSA_DST_LO = *+1 -LZSA_DST_HI = *+2 - STA $AAAA - LDA PUTDST+1 - BNE PUTDST_DONE - DEC PUTDST+2 -PUTDST_DONE - DEC PUTDST+1 - RTS - -GETLARGESRC - JSR GETSRC ; grab low 8 bits - TAX ; move to X - ; fall through grab high 8 bits - -GETSRC -LZSA_SRC_LO = *+1 -LZSA_SRC_HI = *+2 - LDA $AAAA - PHA - LDA GETSRC+1 - BNE GETSRC_DONE - DEC GETSRC+2 -GETSRC_DONE - DEC GETSRC+1 - PLA - RTS - -} else { - - ; Forward decompression -- get and put bytes forward - -GETPUT - JSR GETSRC -PUTDST -LZSA_DST_LO = *+1 -LZSA_DST_HI = *+2 - STA $AAAA - INC PUTDST+1 - BNE PUTDST_DONE - INC PUTDST+2 -PUTDST_DONE - RTS - -GETLARGESRC - JSR GETSRC ; grab low 8 bits - TAX ; move to X - ; fall through grab high 8 bits - -GETSRC -LZSA_SRC_LO = *+1 -LZSA_SRC_HI = *+2 - LDA $AAAA - INC GETSRC+1 - BNE GETSRC_DONE - INC GETSRC+2 -GETSRC_DONE - RTS - -} +; ----------------------------------------------------------------------------- +; Decompress raw LZSA1 block. Create one with lzsa -r +; +; in: +; * LZSA_SRC_LO and LZSA_SRC_HI contain the compressed raw block address +; * LZSA_DST_LO and LZSA_DST_HI contain the destination buffer address +; +; out: +; * LZSA_DST_LO and LZSA_DST_HI contain the last decompressed byte address, +1 +; +; ----------------------------------------------------------------------------- +; Backward decompression is also supported, use lzsa -r -b +; To use it, also define BACKWARD_DECOMPRESS=1 before including this code! +; +; in: +; * LZSA_SRC_LO/LZSA_SRC_HI must contain the address of the last byte of compressed data +; * LZSA_DST_LO/LZSA_DST_HI must contain the address of the last byte of the destination buffer +; +; out: +; * LZSA_DST_LO/LZSA_DST_HI contain the last decompressed byte address, -1 +; +; ----------------------------------------------------------------------------- +; +; Copyright (C) 2019 Emmanuel Marty +; +; 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. +; ----------------------------------------------------------------------------- + +DECOMPRESS_LZSA1 + LDY #$00 + +DECODE_TOKEN + JSR GETSRC ; read token byte: O|LLL|MMMM + PHA ; preserve token on stack + + AND #$70 ; isolate literals count + BEQ NO_LITERALS ; skip if no literals to copy + LSR ; shift literals count into place + LSR + LSR + LSR + CMP #$07 ; LITERALS_RUN_LEN? + BCC PREPARE_COPY_LITERALS ; if not, count is directly embedded in token + + JSR GETSRC ; get extra byte of variable literals count + ; the carry is always set by the CMP above + ; GETSRC doesn't change it + SBC #$F9 ; (LITERALS_RUN_LEN) + BCC PREPARE_COPY_LITERALS + BEQ LARGE_VARLEN_LITERALS ; if adding up to zero, go grab 16-bit count + + JSR GETSRC ; get single extended byte of variable literals count + INY ; add 256 to literals count + BCS PREPARE_COPY_LITERALS ; (*like JMP PREPARE_COPY_LITERALS but shorter) + +LARGE_VARLEN_LITERALS ; handle 16 bits literals count + ; literals count = directly these 16 bits + JSR GETLARGESRC ; grab low 8 bits in X, high 8 bits in A + TAY ; put high 8 bits in Y + TXA + +PREPARE_COPY_LITERALS + TAX + BEQ COPY_LITERALS + INY + +COPY_LITERALS + JSR GETPUT ; copy one byte of literals + DEX + BNE COPY_LITERALS + DEY + BNE COPY_LITERALS + +NO_LITERALS + PLA ; retrieve token from stack + PHA ; preserve token again + BMI GET_LONG_OFFSET ; $80: 16 bit offset + + JSR GETSRC ; get 8 bit offset from stream in A + TAX ; save for later + LDA #$FF ; high 8 bits + BNE GOT_OFFSET ; go prepare match + ; (*like JMP GOT_OFFSET but shorter) + +SHORT_VARLEN_MATCHLEN + JSR GETSRC ; get single extended byte of variable match len + INY ; add 256 to match length + +PREPARE_COPY_MATCH + TAX +PREPARE_COPY_MATCH_Y + TXA + BEQ COPY_MATCH_LOOP + INY + +COPY_MATCH_LOOP + LDA $AAAA ; get one byte of backreference + JSR PUTDST ; copy to destination + +!ifdef BACKWARD_DECOMPRESS { + + ; Backward decompression -- put backreference bytes backward + + LDA COPY_MATCH_LOOP+1 + BNE GETMATCH_DONE + DEC COPY_MATCH_LOOP+2 +GETMATCH_DONE + DEC COPY_MATCH_LOOP+1 + +} else { + + ; Forward decompression -- put backreference bytes forward + + INC COPY_MATCH_LOOP+1 + BNE GETMATCH_DONE + INC COPY_MATCH_LOOP+2 +GETMATCH_DONE + +} + + DEX + BNE COPY_MATCH_LOOP + DEY + BNE COPY_MATCH_LOOP + BEQ DECODE_TOKEN ; (*like JMP DECODE_TOKEN but shorter) + +GET_LONG_OFFSET ; handle 16 bit offset: + JSR GETLARGESRC ; grab low 8 bits in X, high 8 bits in A + +GOT_OFFSET + +!ifdef BACKWARD_DECOMPRESS { + + ; Backward decompression - substract match offset + + STA OFFSHI ; store high 8 bits of offset + STX OFFSLO + + SEC ; substract dest - match offset + LDA PUTDST+1 +OFFSLO = *+1 + SBC #$AA ; low 8 bits + STA COPY_MATCH_LOOP+1 ; store back reference address + LDA PUTDST+2 +OFFSHI = *+1 + SBC #$AA ; high 8 bits + STA COPY_MATCH_LOOP+2 ; store high 8 bits of address + SEC + +} else { + + ; Forward decompression - add match offset + + STA OFFSHI ; store high 8 bits of offset + TXA + + CLC ; add dest + match offset + ADC PUTDST+1 ; low 8 bits + STA COPY_MATCH_LOOP+1 ; store back reference address +OFFSHI = *+1 + LDA #$AA ; high 8 bits + + ADC PUTDST+2 + STA COPY_MATCH_LOOP+2 ; store high 8 bits of address + +} + + PLA ; retrieve token from stack again + AND #$0F ; isolate match len (MMMM) + ADC #$02 ; plus carry which is always set by the high ADC + CMP #$12 ; MATCH_RUN_LEN? + BCC PREPARE_COPY_MATCH ; if not, count is directly embedded in token + + JSR GETSRC ; get extra byte of variable match length + ; the carry is always set by the CMP above + ; GETSRC doesn't change it + SBC #$EE ; add MATCH_RUN_LEN and MIN_MATCH_SIZE to match length + BCC PREPARE_COPY_MATCH + BNE SHORT_VARLEN_MATCHLEN + + ; Handle 16 bits match length + JSR GETLARGESRC ; grab low 8 bits in X, high 8 bits in A + TAY ; put high 8 bits in Y + ; large match length with zero high byte? + BNE PREPARE_COPY_MATCH_Y ; if not, continue + +DECOMPRESSION_DONE + RTS + +!ifdef BACKWARD_DECOMPRESS { + + ; Backward decompression -- get and put bytes backward + +GETPUT + JSR GETSRC +PUTDST +LZSA_DST_LO = *+1 +LZSA_DST_HI = *+2 + STA $AAAA + LDA PUTDST+1 + BNE PUTDST_DONE + DEC PUTDST+2 +PUTDST_DONE + DEC PUTDST+1 + RTS + +GETLARGESRC + JSR GETSRC ; grab low 8 bits + TAX ; move to X + ; fall through grab high 8 bits + +GETSRC +LZSA_SRC_LO = *+1 +LZSA_SRC_HI = *+2 + LDA $AAAA + PHA + LDA GETSRC+1 + BNE GETSRC_DONE + DEC GETSRC+2 +GETSRC_DONE + DEC GETSRC+1 + PLA + RTS + +} else { + + ; Forward decompression -- get and put bytes forward + +GETPUT + JSR GETSRC +PUTDST +LZSA_DST_LO = *+1 +LZSA_DST_HI = *+2 + STA $AAAA + INC PUTDST+1 + BNE PUTDST_DONE + INC PUTDST+2 +PUTDST_DONE + RTS + +GETLARGESRC + JSR GETSRC ; grab low 8 bits + TAX ; move to X + ; fall through grab high 8 bits + +GETSRC +LZSA_SRC_LO = *+1 +LZSA_SRC_HI = *+2 + LDA $AAAA + INC GETSRC+1 + BNE GETSRC_DONE + INC GETSRC+2 +GETSRC_DONE + RTS + +}