qboot: initial work
This commit is contained in:
Vince Weaver
parent
87ad2caad2
commit
f8eb0fd058
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@ -0,0 +1,19 @@
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include ../Makefile.inc
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DOS33_RAW = ../dos33fs-utils/dos33_raw
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all: boot.dsk
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boot.dsk: BOOT
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cp empty.dsk boot.dsk
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$(DOS33_RAW) boot.dsk 0 0 BOOT
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BOOT: boot_sector.o
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ld65 -o BOOT boot_sector.o -C ../linker_scripts/apple2_800.inc
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boot_sector.o: boot_sector.s stage2.s
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ca65 -o boot_sector.o boot_sector.s -l boot_sector.lst
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clean:
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rm -f *~ *.o *.lst BOOT
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@ -0,0 +1,204 @@
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; fast seek/multi-read
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; copyright (c) Peter Ferrie 2015-16
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sectors = $d1 ; user-defined
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firsttrk = $d1 ; user-defined, first track to read
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firstsec = $d1 ; user-defined, first sector to read
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address = $d1 ; user-defined
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entry = $d1d1 ; user-defined
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version = 1
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;memory usage:
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;256 bytes ($bd00-bdff) static table
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grouped = $bd00
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;106 bytes ($xx00-xx69) static table
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preshift = code_end
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zvalue = $fd ;only during init
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znibble = $fe ;only during init
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zmask = $ff ;only during init
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; $26/$27 sector read location (ROM), scratch space (RWTS)
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; $3D sector number
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; at entry (at least on AppleWin) A=1, X=60, Y=0
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; qkumba says cffa cards leave Y at $10
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; 26/27 = 00/09
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; 3D = 1
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; For Disk II booting, the firmware loads track0/sector0
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; to $800 and then jumps to $801
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.org $800
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.byte 1 ; number of sectors for ROM to load
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boot_entry:
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; this code loads two sectors up to $BE/$BF
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lsr ; check sector number
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tay
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adc #$bd
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sta $27 ; set or update address as needed
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asl
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; be, bf, c0 (1011 1011 1100)
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; so if hit $c000 we are done
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bmi not_three ; branch if not 3
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inc $3d ; increment sector (faster to find)
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; call to the read routine in proper slot
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; using rts to jump indirect to
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; $CX5C
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; this routine reads sector in $3D on track $41
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; to address in $26/$27
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; when it's done it jumps back to $801
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txa ; x is slot# << 4
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lsr
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lsr
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lsr
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lsr
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ora #$c0 ; slot to PROM base
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pha
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lda #$5b ;read-1
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pha
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rts
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not_three:
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txa
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ora #$8c ; slot to Q6L
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; Q6L?
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; 1000 1100
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patch_loop:
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iny
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ldx patchtbl-3, y
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sta code_begin, x ;replace placeholders with Q6L
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bne patch_loop
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and #$f8 ;MOTOROFF
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sta slotpatch7+1
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eor #8 ;PHASEOFF
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sta slotpatch8+1
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ldx #$3f
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stx zmask
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inx
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ldy #$7f
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bne skip_ahead ; branch always
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; pad with zeros until $839
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.res $839-*
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;*=$839
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lda #>(entry-1)
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pha
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lda #<(entry-1)
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pha
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jsr preread
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jmp $bf00 ;DOS 3.3 launcher entrypoint
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patchtbl:
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.byte <(slotpatch1+1), <(slotpatch2+1), <(slotpatch3+1), <(slotpatch4+1), <(slotpatch5+1), <(slotpatch6+1)
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indextbl: ;the 0 also terminates the patchtbl list!
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.byte 0, 2, 1, 3
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;construct denibbilisation table
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;pre-shifted for interleave read
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skip_ahead:
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loopaa:
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sty znibble
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tya
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asl
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bit znibble
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beq loopz
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ora znibble
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eor #$ff
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and #$7e
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loopa:
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bcs loopz
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lsr
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bne loopa
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dex
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txa
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asl
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asl
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sta preshift-$16, Y
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loopz:
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dey
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bne loopaa
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;construct 2-bit group table
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sty zvalue
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loopbb:
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lsr zmask
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lsr zmask
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loopb:
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lda indextbl, X
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sta grouped, Y
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inc zvalue
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lda zvalue
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and zmask
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bne loopy
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inx
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txa
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and #3
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tax
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loopy:
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iny
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iny
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iny
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iny
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cpy #3
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bcs loopb
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iny
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cpy #3
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bcc loopbb
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lda #>(entry-1)
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pha
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lda #<(entry-1)
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pha
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jsr preread
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jmp seekread
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preread:
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;copy post-read if necessary
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;push post-read address here
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; pla
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; tax
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; pla
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; tay
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; lda #>(postread-1)
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; pha
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; lda #<(postread-1)
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; pha
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; tya
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; pha
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; txa
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; pha
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lda #<(firsttrk*2)
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sta phase+1
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ldx #sectors
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lda #address
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ldy #firstsec
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rts
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end_code:
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.res $8fe-*
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; traditionally, entry point to jump to at end of loading
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; $be01 in this case
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;*=$8fe
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.byte $be, 1
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.include "stage2.s"
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Binary file not shown.
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@ -0,0 +1,257 @@
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;the following lives on sectors $0E and $0D
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; ????
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.org $be00
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code_begin:
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.byte version
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readnib:
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slotpatch1:
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lda $c0d1 ; ???
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bpl readnib
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rts
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;fill address array for one track
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seekread:
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sty startsec+1
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sta tmpadr+1
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stx total+1
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inittrk:
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sec
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lda #$10
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sbc startsec+1
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cmp total+1
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bcs it_skip
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tax
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it_skip:
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stx partial1
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stx partial2
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jsr seek
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startsec:
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ldy #$d1
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tmpadr:
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tmpadr_loop:
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lda #$d1
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sta addrtbl, y
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inc tmpadr+1
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iny
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dec partial1
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bne tmpadr_loop
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read:
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outer_read:
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jsr readnib
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inner_read:
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cmp #$d5
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bne outer_read
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jsr readnib
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cmp #$aa
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bne inner_read
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tay ; we need Y=#$AA later
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jsr readnib
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eor #$ad ; zero A if match
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beq check_mode
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;if not #$AD, then #$96 is assumed
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ldy #2 ; volume, track, sector
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another:
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jsr readnib
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rol ; set carry
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sta sector+1
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jsr readnib
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and sector+1
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dey
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bpl another
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tay
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ldx addrtbl, Y ; fetch corresponding address
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beq read
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sta sector+1 ; store index for later
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stx adrpatch1+2
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stx adrpatch8+2
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stx adrpatch2+2
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stx adrpatch3+2
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stx adrpatch5+2
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stx adrpatch7+2
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inx
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stx adrpatch9+2
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dex
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dex
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stx adrpatch4+2
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stx adrpatch6+2
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ldy #$fe
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adrpatch1:
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loop2:
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lda $d102, Y
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pha
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iny
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bne loop2
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branch_read:
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bcs read ; branch always
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check_mode:
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cpx #0
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beq read ; loop if not expecting #$AD
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loop33:
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sta tmpval+1 ; zero rolling checksum
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slotpatch2:
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loop4:
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ldx $c0d1
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bpl loop4
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lda preshift-$96, X
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adrpatch2:
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sta $d102, Y ; store 2-bit array
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tmpval:
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eor #$d1
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iny
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bne loop33
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ldy #$aa
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slotpatch3:
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loop5:
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ldx $c0d1
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bpl loop5
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eor preshift-$96, X
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adrpatch3:
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ldx $d102, Y ; bit2tbl
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eor grouped+2, X ; first 86 nibbles use group bits 0-1
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adrpatch4:
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sta $d156, y
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iny
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bne loop5
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and #$fc
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ldy #$aa
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slotpatch4:
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loop6:
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ldx $c0d1
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bpl loop6
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eor preshift-$96, X
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adrpatch5:
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ldx $d102, Y ; bit2tbl
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eor grouped+1, X ; second 86 nibbles use group bits 2-3
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adrpatch6:
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sta $d1ac, Y
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iny
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bne loop6
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and #$fc
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ldx #$ac
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slotpatch5:
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loop7:
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ldy $c0d1
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bpl loop7
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eor preshift-$96, Y
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adrpatch7:
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ldy $d100, X ; bit2tbl
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eor grouped, Y ; last 84 nibbles use group bits 4-5
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adrpatch8:
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sta $d100, x
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inx
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bne loop7
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and #$fc
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slotpatch6:
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loop8:
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ldy $c0d1
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bpl loop8
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eor preshift-$96, Y
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cmp #1 ; carry = !zero
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ldy #1
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loop9:
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pla
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adrpatch9:
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sta $d100, Y
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dey
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bpl loop9
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branch_read2:
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bcs branch_read ; branch if checksum failure
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sector:
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ldy #$d1
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txa
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sta addrtbl, Y ; zero corresponding address
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dec total+1
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dec partial2 ; adjust remaining count (faster than looping over array)
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sec
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bne branch_read2 ; read all requested sectors in one track
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total:
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ldx #$d1
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beq driveoff
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inc phase+1
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inc phase+1 ; update current track
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jmp inittrk
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driveoff:
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slotpatch7:
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lda $c0d1
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seekret:
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rts
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seek:
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lda #0
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sta step+1
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copy_cur:
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curtrk:
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lda #0
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sta tmpval+1
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sec
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phase:
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sbc #$d1
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beq seekret
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eor #$ff
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inc curtrk+1
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cmp step+1
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bcc loop10
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step:
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lda #$d1
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loop10:
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cmp #8
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bcs loop11
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tay
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sec
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loop11:
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lda curtrk+1
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ldx step1, Y
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bne loop12
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loopmmm:
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clc
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lda tmpval+1
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ldx step2, Y
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loop12:
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stx sector+1
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and #3
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rol
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tax
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slotpatch8:
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sta $c0d1, X
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loopmm:
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ldx #$13
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loopm:
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dex
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bne loopm
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dec sector+1
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bne loopmm
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lsr
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bcs loopmmm
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inc step+1
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bne copy_cur
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step1: .byte 1, $30, $28, $24, $20, $1e, $1d, $1c
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step2: .byte $70, $2c, $26, $22, $1f, $1e, $1d, $1c
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addrtbl: .res 16
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partial1 = *
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partial2 = partial1+1
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code_end=partial2+1
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