updates to floppy code
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@@ -1,84 +0,0 @@
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; Helper routines for low-level disk operations
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lowlevel_fd_ensure_presence_refresh:
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jsr lowlevel_fd_wait_clr_BUSY ; to be extra sure
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; XXX stepping head is definitely needed, but probably still not enough
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; lda #%00011000 ; step head 1 track in (XXX: check if it is really in)
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; sta FDC_COMMAND ; $D081
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; jsr lowlevel_fd_wait_clr_BUSY
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; lda #%00010000 ; step head 1 track out (XXX: check if it is really out)
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; sta FDC_COMMAND ; $D081
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; jsr lowlevel_fd_wait_clr_BUSY
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; FALLTROUGH
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lowlevel_fd_ensure_presence:
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lda FDC_STATUS_B ; $D083 ; check if disk is inserted
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and #$08
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beq @not_present
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rts
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@not_present:
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pla
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pla
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jsr lowlevel_fd_motor_off ; if disk not present, disable drive motor
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; XXX set error code, invalidate buffers, etc.
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sec
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rts
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lowlevel_fd_motor_on:
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lda FDC_CONTROL
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and #%00100000
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bne lowlevel_fd_rts ; if motor already enabled, do nothing
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; XXX find out why it is not disabled at all
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; lda #%00100000 ; enable drive motor and LED
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; tsb FDC_CONTROL ; $D080
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; Allow some time for spin-up; according to https://wiki.osdev.org/Floppy_Disk_Controller
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; 300 ms should be more than enough
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; XXX reenable this
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; phx
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; ldx #$0F
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; jsr wait_x_bars
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; plx
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bra lowlevel_fd_wait_clr_BUSY
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lowlevel_fd_motor_off:
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lda #%00100000 ; disable drive motor and LED
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trb FDC_CONTROL ; $D080
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; FALLTROUGH
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lowlevel_fd_wait_clr_BUSY:
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bit FDC_STATUS_A ; $D082
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bmi lowlevel_fd_wait_clr_BUSY
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rts
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lowlevel_fd_wait_set_RDREQ:
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bit FDC_STATUS_B ; $D083
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bpl lowlevel_fd_wait_set_RDREQ
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; FALLTROUGH
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lowlevel_fd_rts:
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rts
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@@ -1,5 +1,6 @@
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; Read a sector pair from a block device
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; Read a sector pair from a block device, flow partially based on:
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; - https://github.com/MEGA65/mega65-tools/blob/master/src/tests/floppytest.c
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lowlevel_xx_readsector:
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@@ -11,48 +12,46 @@ lowlevel_xx_readsector:
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lowlevel_fd_readsector:
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; Set drive
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lda #%00001111 ; set drive 0 (internal) and side 0
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trb FDC_CONTROL ; $D080
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cpx #$01
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beq @1
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lda #%00000001 ; if needed, switch to drive 1 (external)
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tsb FDC_CONTROL
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@1:
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; Ensure disk is present
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jsr lowlevel_fd_ensure_presence_refresh
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; Check if buffer contains data from given track
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; XXX compare device and unit too
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; Check if buffer contains data from given track, sector, drive
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lda PAR_TRACK
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cmp BUFTAB_TRACK+1
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bne lowlevel_readsector_force
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; Check if sectors match
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bne lowlevel_fd_readsector_force
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lda PAR_SECTOR
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and #%11111110
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cmp BUFTAB_SECTOR+1
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bne lowlevel_readsector_force
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bne lowlevel_fd_readsector_force
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; XXX compare drive
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; Data already loaded into buffer - do nothing
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clc
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rts
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lowlevel_readsector_force:
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lowlevel_fd_readsector_force:
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jsr lowlevel_fd_motor_on ; enable drive motor and LED
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jsr lowlevel_fd_ensure_presence
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; Set drive, motor ON
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lda #%10000000 ; select floppy buffer
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lda #$68
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cpx #$01
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beq @1
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inc
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@1:
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sta FDC_CONTROL ; $D080
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; Select floppy buffer
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lda #%10000000
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trb SD_BUFCTL ; $D689
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; Wait until BUSY flag clears
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@2:
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lda FDC_STATUS_A ; $D082
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bmi @2
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; Select physical track and sector based on logical ones from PAR_TRACK and PAR_SECTOR
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lda PAR_TRACK
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@@ -84,21 +83,30 @@ lowlevel_readsector_force:
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inc
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sta FDC_SECTOR ; $D085
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; Reset buffers
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lda #$00
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sta FDC_COMMAND ; $D081
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; Ask the controller to read the sector XXX how to detect errors, missing disk, etc.?
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lda #$40
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sta FDC_COMMAND ; $D081
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jsr lowlevel_fd_wait_set_RDREQ ; wait till sector is found
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jsr lowlevel_fd_wait_clr_BUSY ; wait for BUSY flag to clear
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; Wait for busy flag to assert XXX how much? 1 second? most likelly too much...
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; Wait for DRQ and EQ flags to go high
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ldy #71
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@3:
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ldx #$00
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jsr wait_x_bars
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dey
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bne @3
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@lp1:
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; Wait until BUSY flag clears
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@4:
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lda FDC_STATUS_A ; $D082
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and #%01100000
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cmp #%01000000 ; XXX is this correct? .A seems to stay at $40 at this point
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bne @lp1
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bmi @4
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; Copy sector to buffer in RAM
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@@ -125,3 +133,13 @@ lowlevel_readsector_force:
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clc
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rts
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lowlevel_fd_motor_off:
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; XXX set correct drive
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lda #$00
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sta FDC_CONTROL ; $D080
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rts
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