; Loader for MIST .include "zp.inc" .include "hardware.inc" ; the TITLE program sets $05 with which thing to load ; this part of the program stays resident, so when a level ends ; it changes $05 (WHICH_LOAD) and this code loads the proper executable nibtbl = $300 ; nothing uses the bottom 128 bytes of $300, do they? bit2tbl = $380 ; bit2tbl: .res 86 ; = nibtbl+128 filbuf = $3D6 ; filbuf: .res 4 ; = bit2tbl+86 ; read any file slot 6 version ; based on FASTLD6 and RTS copyright (c) Peter Ferrie 2011-2013,2018 ; modified to assembled with ca65 -- vmw ; added code to patch it to run from current disk slot -- vmw ; WHICH_LOAD = $05 ; thing to load ; adrlo = $26 ; constant from boot prom ; adrhi = $27 ; constant from boot prom ; tmpsec = $3c ; constant from boot prom ; reqsec = $3d ; constant from boot prom ; sizelo = $44 ; sizehi = $45 ; secsize = $46 ; namlo = $f8 ; namhi = $f9 ; TEMPY = $fa ; step = $fd ; state for stepper motor ; tmptrk = $fe ; temporary copy of current track ; phase = $ff ; current phase for /seek ; OUTL = $fe ; for picking filename ; OUTH = $ff dirbuf = $c00 ; note, don't put this immediately below ; the value being read as destaddr-4 ; is temporarily overwritten during read ; process FILENAME = $280 ;=================================================== ;=================================================== ; START / INIT ;=================================================== ;=================================================== LOAD_TITLE = $0 LOAD_MIST = $1 LOAD_MECHE = $2 LOAD_SELENA = $3 LOAD_OCTAGON = $4 LOAD_STONEDSHIP = $5 LOAD_CHANNEL = $6 LOAD_ENDING = $7 loader_start: lda #LOAD_TITLE sta WHICH_LOAD jsr init ; unhook DOS, init nibble table ;=================================================== ;=================================================== ; SETUP THE FILENAME ;=================================================== ;=================================================== which_load_loop: lda WHICH_LOAD asl tay lda filenames,Y sta OUTL lda filenames+1,Y sta OUTH lda WHICH_LOAD bne load_other load_intro: lda #<$4000 sta entry_smc+1 lda #>$4000 sta entry_smc+2 jmp actual_load load_other: lda #<$1400 sta entry_smc+1 lda #>$1400 sta entry_smc+2 actual_load: ;=================================================== ;=================================================== ; SET UP DOS3.3 FILENAME ;=================================================== ;=================================================== load_file_and_execute: jsr opendir_filename entry_smc: jsr $1000 ; jump to common entry point ; hope they updated the WHICH_LOAD value jmp which_load_loop ;============================== ; setup filename then open/load opendir_filename: ; clear out the filename with $A0 (space) lda #FILENAME sta namhi ldy #29 wipe_filename_loop: lda #$A0 sta (namlo),Y dey bpl wipe_filename_loop ldy #0 copy_filename_loop: lda (OUTL),Y beq copy_filename_done ora #$80 sta (namlo),Y iny bne copy_filename_loop copy_filename_done: jsr opendir ; open and read entire file into memory rts filenames: .word intro_filename .word mist_filename,meche_filename,selena_filename,octagon_filename .word ending_filename intro_filename: .byte "MIST_TITLE",0 mist_filename: .byte "MIST",0 meche_filename: .byte "MECHE",0 selena_filename: .byte "SELENA",0 octagon_filename: .byte "OCTAGON",0 ending_filename: .byte "ENDING",0 ;=================================================== ;=================================================== ; INIT (build nibble table) ;=================================================== ;=================================================== ;unhook DOS and build nibble table init: ; patch to use current drive ; locate input paramater list jsr $3E3 ; result is in A:Y sta $FF sty $FE ldy #1 lda ($FE),y ; list+1 should have slot<<8 ora #$80 ; add in $80 ; c0e0 sta mlsmc06+1 ; c0e8 clc adc #8 sta mlsmc02+1 sta mlsmc07+1 ; c0e9 clc adc #1 sta mlsmc01+1 ; c0ec clc adc #3 sta mlsmc03+1 sta mlsmc04+1 sta mlsmc05+1 jsr $fe93 ; clear COUT jsr $fe89 ; clear KEYIN ;======================== ; Create nibble table ; Note: the table starts 16 bytes in, and is sparse ; so it doesn't entirely look like the DOS33 table at ldy #0 ldx #3 L1: stx $3c ; store tempx (3?) txa ; a=x (a=3) asl ; a*=2 (a=6) bit $3c ; a&tempx, set N/V (a=6) beq L3 ; if 0, skip to L3 ora $3c ; a|=tempx (a=7) eor #$ff ; a=~a (a=f8) and #$7e ; a&=0x7e 0111 1110 (a=78) L2: bcs L3 ; this set way back at asl?? lsr ; a>>1 a=3c c=0 ; a=1e c=0 ; a=0f c=0 ; a=07 c=1 bne L2 ; if a!=0 goto l2 tya ; if a==0, a=y sta nibtbl, x ; write out to table iny ; increment y L3: inx ; increment x x=4, a=0f bpl L1 ; loop while high bit not set rts ;=================================================== ;=================================================== ; file not found ;=================================================== ;=================================================== file_not_found: mlsmc07:lda $c0e8 ; turn off drive motor? jsr TEXT jsr HOME ldy #0 lda #disk_string sta OUTH quick_print: lda (OUTL),Y beq quick_print_done jsr COUT1 iny jmp quick_print quick_print_done: ; rts ; jsr quick_print fnf_keypress: lda KEYPRESS bpl fnf_keypress bit KEYRESET jmp which_load_loop disk_string: .byte "INSERT OTHER DISK, PRESS RETURN",0 ;=================================================== ;=================================================== ; OPENDIR: actually load the file ;=================================================== ;=================================================== ; turn on drive and read volume table of contents opendir: mlsmc01:lda $c0e9 ; turn slot#6 drive on ldx #0 stx adrlo ; zero out adrlo stx secsize ; zero out secsize lda #$11 ; a=$11 (VTOC) jsr readdirsec firstent: lda dirbuf+1 ; lock if entry not found entry_not_found: beq file_not_found ; read directory sector ldx dirbuf+2 jsr seekread1 ldy #7 ;number of directory entries in a sector ldx #$2b ;offset of filename in directory entry nextent: tya pha ; was **phy** txa pha ; was **phx** ldy #$1d ; match name backwards (slower but smaller) L4: lda (namlo), y cmp dirbuf, x beq foundname pla ; move to next directory in this block, if possible clc adc #$23 tax pla tay ; was **ply** dey bne nextent beq firstent ; was **bra** foundname: dex dey bpl L4 pla tay ; was **ply** pla ; read track/sector list lda dirbuf-32, y ldx dirbuf-31, y jsr seekread1 ; read load offset and length info only, initially lda #filbuf jsr seekread ; reduce load offset by 4, to account for offset and length sec lda filbuf sbc #4 sta adrlo lda filbuf+1 sbc #0 sta adrhi ; save on stack bytes that will be overwritten by extra read ldy #3 L5: lda (adrlo), y pha dey bpl L5 lda adrhi pha lda adrlo pha ; increase load size by 4, to account for offst and length lda filbuf+2 adc #3 sta sizelo sta secsize lda filbuf+3 adc #0 sta sizehi beq readfirst lda #0 ; was **stz secsize** sta secsize readfirst: ldy #$0c ; read a file sector readnext: tya pha lda dirbuf, y ; A = track ldx dirbuf+1, y ; x = sector jsr seekread1 pla tay ; if low count is non-zero then we are done ; (can happen only for partial last block) lda secsize bne readdone ; continue if more than $100 bytes left dec sizehi bne L6 ; set read size to min(length, $100) lda sizelo beq readdone sta secsize L6: inc adrhi iny iny bne readnext ; save current address for after t/s read lda adrhi pha lda adrlo pha lda #0 sta adrlo ; was **stz adrlo** ; read next track/sector sector lda dirbuf+1 ldx dirbuf+2 jsr readdirsec clc ; restore current address readdone: pla sta adrlo ; code originally had this backwards pla sta adrhi bcc readfirst mlsmc02:lda $c0e8 ; restore from stack bytes that were overwritten by extra read ldx #3 ldy #0 L7: pla sta (adrlo), y iny dex bpl L7 rts ;====================== ; readdirsec ;====================== ; a = track? ; x = sector? readdirsec: ldy #>dirbuf seekread: sty adrhi seekread1: sta phase lda sectbl, x sta reqsec jsr readadr ; if track does not match, then seek cpx phase beq checksec jsr seek ;========================================= ; re merge in with qkumba's recent changes ; to fix seek problem? ;========================================= ; [re-]read sector re_read_addr: jsr readadr checksec: cmp reqsec bne re_read_addr ;========================= ; read sector data ;========================= readdata: jsr readd5aa eor #$ad ; zero A if match bne re_read_addr L12: mlsmc03:ldx $c0ec ; read until valid data (high bit set) bpl L12 eor nibtbl-$80, x sta bit2tbl-$aa, y iny bne L12 L13: mlsmc04:ldx $c0ec ; read until valid data (high bit set) bpl L13 eor nibtbl-$80, x sta (adrlo), y ; the real address iny cpy secsize bne L13 ldy #0 L14: ldx #$a9 L15: inx beq L14 lda (adrlo), y lsr bit2tbl-$aa, x rol lsr bit2tbl-$aa, x rol sta (adrlo), y iny cpy secsize bne L15 rts ; no tricks here, just the regular stuff ;======================= ; readaddr -- read the address field ;======================= ; Find address field, put track in cutrk, sector in tmpsec readadr: jsr readd5aa cmp #$96 bne readadr ldy #3 ; three? ; first read volume/volume ; then track/track ; then sector/sector? adr_read_two_bytes: tax jsr readnib rol sta tmpsec jsr readnib and tmpsec dey bne adr_read_two_bytes rts ;======================== ; make sure we see the $D5 $AA pattern readd5aa: L16: jsr readnib L17: cmp #$d5 bne L16 jsr readnib cmp #$aa bne L17 tay ; we need Y=#$AA later readnib: mlsmc05:lda $c0ec ; read until valid (high bit set) bpl readnib seekret: rts ;===================== ; SEEK ;===================== ; current track in X? ; desired track in phase seek: ldy #0 sty step asl phase ; multiply by two txa ; current track? asl ; mul by two copy_cur: tax sta tmptrk sec sbc phase beq L22 bcs L18 eor #$ff inx bcc L19 L18: sbc #1 dex L19: cmp step bcc L20 lda step L20: cmp #8 bcs L21 tay sec L21: txa pha ldx step1, y L22: php bne L24 L23: clc lda tmptrk ldx step2, y L24: stx tmpsec and #3 rol tax lsr mlsmc06:lda $c0e0, x L25: ldx #$12 L26: dex bpl L26 dec tmpsec bne L25 bcs L23 plp beq seekret pla inc step bne copy_cur step1: .byte $01, $30, $28, $24, $20, $1e, $1d, $1c step2: .byte $70, $2c, $26, $22, $1f, $1e, $1d, $1c sectbl: .byte $00,$0d,$0b,$09,$07,$05,$03,$01,$0e,$0c,$0a,$08,$06,$04,$02,$0f ; From $BA96 of DOS33 ;nibtbl: .res 128 ; = * ; .byte $00,$01,$98,$99,$02,$03,$9C,$04 ; $BA96 ; 00 ; .byte $05,$06,$A0,$A1,$A2,$A4,$A4,$A5 ; $BA9E ; 08 ; .byte $07,$08,$A8,$A9,$AA,$09,$0A,$0B ; $BAA6 ; 10 ; .byte $0C,$0D,$B0,$B1,$0E,$0F,$10,$11 ; $BAAE ; 18 ; .byte $12,$13,$B8,$14,$15,$16,$17,$18 ; $BAB6 ; 20 ; .byte $19,$1A,$C0,$C1,$C2,$C3,$C4,$C5 ; $BABE ; 28 ; .byte $C6,$C7,$C8,$C9,$CA,$1B,$CC,$1C ; $BAC6 ; 30 ; .byte $1D,$1E,$D0,$D1,$D2,$1E,$D4,$D5 ; $BACE ; 38 ; .byte $20,$21,$D8,$22,$23,$24,$25,$26 ; $BAD6 ; 40 ; .byte $27,$28,$E0,$E1,$E2,$E3,$E4,$29 ; $BADE ; 48 ; .byte $2A,$2B,$E8,$2C,$2D,$2E,$2F,$30 ; $BAE6 ; 50 ; .byte $31,$32,$F0,$F1,$33,$34,$35,$36 ; $BAEE ; 58 ; .byte $37,$38,$F8,$39,$3A,$3B,$3C,$3D ; $BAF6 ; 60 ; .byte $3E,$3F,$13,$00,$01,$02,$01,$00 ; $BAFE ; 68 ; .byte $00,$00,$00,$00,$00,$00,$00,$00 ; .byte $00,$00,$00,$00,$00,$00,$00,$00 ;bit2tbl: .res 86 ; = nibtbl+128 ;filbuf: .res 4 ; = bit2tbl+86 ;dataend = filbuf+4 loader_end: .assert (3, error, "loader too big"