mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-11-18 21:06:31 +00:00
222 lines
3.6 KiB
ArmAsm
222 lines
3.6 KiB
ArmAsm
; fast seek/multi-read
|
|
; copyright (c) Peter Ferrie 2015-16
|
|
|
|
sectors = 33 ; user-defined
|
|
firsttrk = 3 ; user-defined, first track to read
|
|
firstsec = 0 ; user-defined, first sector to read
|
|
address = $1f ; user-defined
|
|
entry = $1f00 ; user-defined
|
|
version = 1
|
|
|
|
;memory usage:
|
|
;256 bytes ($bd00-bdff) static table
|
|
grouped = $bd00
|
|
;106 bytes ($xx00-xx69) static table
|
|
preshift = code_end
|
|
zvalue = $fd ; only during init
|
|
znibble = $fe ; only during init
|
|
zmask = $ff ; only during init
|
|
|
|
|
|
; $26/$27 sector read location (ROM)
|
|
; $3D sector number (ROM)
|
|
|
|
|
|
; at entry (at least on AppleWin) A=1, X=60, Y=0
|
|
; qkumba says cffa cards leave Y at $10
|
|
; 26/27 = 00/09
|
|
; 3D = 1
|
|
|
|
; For Disk II booting, the firmware loads track0/sector0
|
|
; to $800 and then jumps to $801
|
|
|
|
.org $800
|
|
.byte 1 ; number of sectors for ROM to load
|
|
|
|
boot_entry:
|
|
; this code loads two sectors up to $BE/$BF
|
|
|
|
lsr ; check sector number
|
|
tay
|
|
adc #$bd
|
|
sta $27 ; set or update address as needed
|
|
asl
|
|
; be, bf, c0 (1011 1011 1100)
|
|
; so if hit $c000 we are done
|
|
|
|
bmi not_three ; branch if not 3
|
|
|
|
inc $3d ; increment sector (faster to find)
|
|
|
|
; call to the read routine in proper slot
|
|
; using rts to jump indirect to
|
|
; $CX5C
|
|
|
|
; this routine reads sector in $3D on track $41
|
|
; to address in $26/$27
|
|
; when it's done it jumps back to $801
|
|
|
|
txa ; x is slot# << 4
|
|
lsr
|
|
lsr
|
|
lsr
|
|
lsr
|
|
ora #$c0 ; slot to PROM base
|
|
pha
|
|
lda #$5b ;read-1
|
|
pha
|
|
rts
|
|
|
|
not_three:
|
|
|
|
; patch self modifying code for Q6L read
|
|
|
|
txa
|
|
ora #$8c ; slot to Q6L
|
|
; Q6L?
|
|
; if slot 6, after this A is $EC
|
|
patch_loop:
|
|
iny
|
|
ldx patchtbl-3, Y
|
|
sta code_begin, X ; replace placeholders with Q6L
|
|
; BE02 = EC? lda c0ec
|
|
; so sets to c08c (Q6L)
|
|
|
|
bne patch_loop
|
|
|
|
; patch self-modifying code for turning motor off
|
|
|
|
and #$f8 ; MOTOROFF (c088)
|
|
sta slotpatch7+1
|
|
|
|
; patch self-modifying code for phase off
|
|
|
|
eor #8 ; PHASEOFF (c080)
|
|
sta slotpatch8+1
|
|
|
|
ldx #$3f
|
|
stx zmask
|
|
inx
|
|
ldy #$7f
|
|
|
|
bne skip_ahead ; branch always
|
|
|
|
; pad with zeros until $839
|
|
; $839 is the entry point
|
|
; adjusts address at $8FE to be entry point
|
|
; jumps to boot 2
|
|
.res $839-*
|
|
|
|
lda #>(entry-1)
|
|
pha
|
|
lda #<(entry-1)
|
|
pha
|
|
jsr preread
|
|
jmp $bf00 ; DOS 3.3 launcher entrypoint
|
|
|
|
patchtbl:
|
|
.byte <(slotpatch1+1), <(slotpatch2+1), <(slotpatch3+1)
|
|
.byte <(slotpatch4+1), <(slotpatch5+1), <(slotpatch6+1)
|
|
indextbl: ;the 0 also terminates the patchtbl list!
|
|
.byte 0, 2, 1, 3
|
|
|
|
|
|
;construct denibbilisation table
|
|
;pre-shifted for interleave read
|
|
|
|
skip_ahead:
|
|
loopaa:
|
|
sty znibble
|
|
tya
|
|
asl
|
|
bit znibble
|
|
beq loopz
|
|
ora znibble
|
|
eor #$ff
|
|
and #$7e
|
|
loopa:
|
|
bcs loopz
|
|
lsr
|
|
bne loopa
|
|
dex
|
|
txa
|
|
asl
|
|
asl
|
|
sta preshift-$16, Y
|
|
loopz:
|
|
dey
|
|
bne loopaa
|
|
|
|
;construct 2-bit group table
|
|
|
|
sty zvalue
|
|
loopbb:
|
|
lsr zmask
|
|
lsr zmask
|
|
loopb:
|
|
lda indextbl, X
|
|
sta grouped, Y
|
|
inc zvalue
|
|
lda zvalue
|
|
and zmask
|
|
bne loopy
|
|
inx
|
|
txa
|
|
and #3
|
|
tax
|
|
loopy:
|
|
iny
|
|
iny
|
|
iny
|
|
iny
|
|
cpy #3
|
|
bcs loopb
|
|
iny
|
|
cpy #3
|
|
bcc loopbb
|
|
lda #>(entry-1)
|
|
pha
|
|
lda #<(entry-1)
|
|
pha
|
|
jsr preread
|
|
|
|
jmp seekread
|
|
|
|
preread:
|
|
|
|
;copy post-read if necessary
|
|
;push post-read address here
|
|
; pla
|
|
; tax
|
|
; pla
|
|
; tay
|
|
; lda #>(postread-1)
|
|
; pha
|
|
; lda #<(postread-1)
|
|
; pha
|
|
; tya
|
|
; pha
|
|
; txa
|
|
; pha
|
|
|
|
lda #<(firsttrk*2)
|
|
sta phase+1
|
|
ldx #sectors
|
|
lda #address
|
|
ldy #firstsec
|
|
rts
|
|
|
|
|
|
|
|
end_code:
|
|
|
|
.res $8fe-*
|
|
|
|
; traditionally, entry point to jump to at end of loading
|
|
; $be01 in this case
|
|
;*=$8fe
|
|
.byte $be, 1
|
|
|
|
|
|
.include "stage2.s"
|