decompress.asm

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; decompress.asm
;   Data decompression
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;.include "../macros.asm"

.macro  dcmp_fetch_byte
        lda         [dcmp_srcadd],y
        iny
        bne         :+
        jsr         dcmp_nextbank
:
        ; next code
.endmac

.macro  dcmp_chk_lz_end
        pha
        lda         dcmp_lzcctr
        beq         :+
        jsr         dcmp_declzcctr
:
        pla
.endmac

label_80a116:
        php
        phb
        regsize     2, 2
        ldy         dcmp_srcadd
        stz         dcmp_srcadd
        regsize     1, NULL
        stz         dcmp_lzcctr
        lda         dcmp_dstbnk
        pha
        plb
        ldx         dcmp_dstadd
        jmp         dcmp_main

dcmp_fetch:
        dcmp_fetch_byte
        dcmp_chk_lz_end
        rts

dcmp_declzcctr:
        dec
        sta         dcmp_lzcctr
        bne         :+
        lda         dcmp_bnkstr
        sta         dcmp_srcbnk
        ldy         dcmp_addstr
:
        rts

dcmp_nextbank:
        inc         dcmp_srcbnk
        ldy         #$8000
        rts

dcmp_nibl30:
        sta         dcmp_work
        asl
        bpl         dcmp_nibl50
        and         #$20
        beq         dcmp_nibl40
        lda         dcmp_work
        asl
        asl
        asl
        asl
        ora         #$0f
        sta         a:$0000,x
        inx
        lda         #$1f
        bra         dcmp_nibl10
dcmp_nibl40:
        lda         dcmp_work
        and         #$0f
        ora         #$f0
        sta         a:$0000,x
        inx
        lda         #$0f
        bra         dcmp_nibl10
dcmp_nibl50:
        and         #$20
        beq         dcmp_nibl60
        lda         dcmp_work
        asl
        asl
        asl
        asl
        sta         a:$0000,x
        inx
        lda         #$10
        bra         dcmp_nibl10
dcmp_nibl60:
        lda         dcmp_work
        and         #$0f
        sta         a:$0000,x
        inx
        lda         #$00
        bra         dcmp_nibl10
dcmp_nibl:
        and         #$0f
        inc
        sta         dcmp_work+2
        jsr         dcmp_fetch
        cmp         #$80
        bcs         dcmp_nibl30
dcmp_nibl10:
        cmp         #$10
        bcc         dcmp_nibl20
        and         #$0f
        sta         dcmp_work
dcmp_nibl15:
        jsr         dcmp_fetch
        sta         dcmp_work+1
        and         #$f0
        ora         dcmp_work
        sta         a:$0000,x
        inx
        dec         dcmp_work+2
        bmi         dcmp_niblr
        lda         dcmp_work+1
        asl
        asl
        asl
        asl
        ora         dcmp_work
        sta         a:$0000,x
        inx
        dec         dcmp_work+2
        bpl         dcmp_nibl15
        jmp         dcmp_main

dcmp_nibl20:
        asl
        asl
        asl
        asl
        sta         dcmp_work
dcmp_nibl25:
        jsr         dcmp_fetch
        sta         dcmp_work+1
        lsr
        lsr
        lsr
        lsr
        ora         dcmp_work
        sta         a:$0000,x
        inx
        dec         dcmp_work+2
        bmi         dcmp_niblr
        lda         dcmp_work+1
        and         #$0f
        ora         dcmp_work
        sta         a:$0000,x
        inx
        dec         dcmp_work+2
        bpl         dcmp_nibl25
dcmp_niblr:
        jmp         dcmp_main

dcmp_chkcmdmsk10:
        cmp         #%01010000
        bcc         dcmp_nibl
        and         #$0f
        sta         dcmp_work+2
dcmp_rep2:
        dcmp_fetch_byte
        dcmp_chk_lz_end
        sta         a:$0000,x
        inx
        sta         a:$0000,x
        inx
        dec         dcmp_work+2
        bpl         dcmp_rep2
        jmp         dcmp_main

dcmp_chkcmdmsk:
        lsr
        cmp         #%01100000
        bcc         dcmp_chkcmdmsk10
        xba
        dcmp_fetch_byte
        dcmp_chk_lz_end
        sta         dcmp_work
        xba
        cmp         #%01110000
        and         #$0f
        inc
        sta         dcmp_work+2
        bcs         dcmp_alt2
dcmp_alt1:
        lda         dcmp_work
        sta         a:$0000,x
        inx
        dcmp_fetch_byte
        dcmp_chk_lz_end
        sta         a:$0000,x
        inx
        dec         dcmp_work+2
        bpl         dcmp_alt1
        bra         dcmp_main

dcmp_alt2:
        dcmp_fetch_byte
        dcmp_chk_lz_end
        sta         a:$0000,x
        inx
        lda         dcmp_work
        sta         a:$0000,x
        inx
        dec         dcmp_work+2
        bpl         dcmp_alt2
        bra         dcmp_main

dcmp_bitmskcmd:
        bmi         dcmp_chkcmdmsk
        lsr
        sta         dcmp_work+2
dcmp_rawd:
        dcmp_fetch_byte
        dcmp_chk_lz_end
        sta         a:$0000,x
        inx
        dec         dcmp_work+2
        bpl         dcmp_rawd
dcmp_main:
        dcmp_fetch_byte
        dcmp_chk_lz_end
        asl
        bcc         dcmp_bitmskcmd
        bmi         dcmp_prefixcmd
        lsr
        pha
        lsr
        lsr
        inc
        sta         dcmp_work+2
        pla
        and         #$03
        xba
label_80a2c2:
        dcmp_fetch_byte
        phy
        regsize     2, NULL
        sta         dcmp_work
        txa
        sec
        sbc         dcmp_work
        tay
        regsize     1, NULL
label_80a2d6:
        lda         a:$0000,y
        sta         a:$0000,x
        iny
        inx
        dec         dcmp_work+2
        bpl         label_80a2d6
        ply
label_80a2e3:
        lda         dcmp_lzcctr
        beq         dcmp_main
        jsr         dcmp_declzcctr
        bra         dcmp_main

dcmp_prefixcmd:
        ror
        cmp         #%11100000
        bcs         dcmp_rle1
        and         #$1f
        xba
        dcmp_fetch_byte
        dcmp_chk_lz_end
        regsize     2, NULL
        asl
        regsize     1, NULL
        lsr
        xba
        inc
        sta         dcmp_work+2
        bra         label_80a2c2

dcmp_rle1:
        cmp         #%11110000
        bcs         dcmp_rle2
        and         #%00001111
        sta         dcmp_work+1
        dcmp_fetch_byte
        dcmp_chk_lz_end
        sta         dcmp_work
        dcmp_fetch_byte
        phy
        pha
        pha
        regsize     2, NULL
        lda         dcmp_work
        clc
        adc         #3
        lsr
        tay
        pla
dcmp_rle1_10:
        sta         a:$0000,x
        inx
        inx
        dey
        bne         dcmp_rle1_10
        regsize     1, NULL
        bcc         dcmp_rle1_20
        sta         a:$0000,x
        inx
dcmp_rle1_20:
        ply
        bra         label_80a2e3
dcmp_rle2:
        cmp         #%11111000
        bcs         dcmp_lzcf
        and         #%00000111
        adc         #2
        sta         dcmp_work+2
        dcmp_fetch_byte
label_80a367:
        sta         a:$0000,x
        inx
        dec         dcmp_work+2
        bpl         label_80a367
        jmp         label_80a2e3

dcmp_lzcf:
        cmp         #%11111100
        bcs         dcmp_lzcn
        and         #%00000011
        xba
        dcmp_fetch_byte
        regsize     2, NULL
        asl
        asl
        asl
        regsize     1, NULL
        lsr
        lsr
        lsr
        xba
        pha
        dcmp_fetch_byte
        regsize     2, NULL
        clc
        adc         #3
dcmp_lzc_calc:
        sty         dcmp_addstr
        sta         dcmp_work
        regsize     1, NULL
        lda         dcmp_srcbnk
        sta         dcmp_bnkstr
        regsize     2, NULL
        tya
        sec
        sbc         dcmp_work
        bmi         label_80a3b3
        clc
        adc         #$8000
        dec         dcmp_srcbnk
label_80a3b3:
        tay
        regsize     1, NULL
        pla
        clc
        adc         #3
        sta         dcmp_lzcctr
        jmp         dcmp_main

dcmp_lzcn:
        cmp         #%11111110
        bcs         dcmpret
        and         #%00000001
        xba
        dcmp_fetch_byte
        regsize     2, NULL
        asl
        asl
        regsize     1, NULL
        xba
        pha
        xba
        lsr
        lsr
        regsize     2, NULL
        and         #%0000000000111111
        inc
        inc
        bra         dcmp_lzc_calc
dcmpret:
        plb
        plp
        rtl