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cc65/libsrc/geos-cbm/disk/dio_stc.s
Greg King 6fd56bf9b6 Fixed bugs in the geos-cbm DIO sector-number converter functions.
* The 16-bit comparison code actually didn't compare the high byte.
* This implementation supports only the 1541, 1571, and 1581; but, it didn't exclude the other drive types that GEOS supports.
* Two error code numbers were swapped.
* A 1571 converter didn't catch sector numbers that are too high.
* A 1581 converter didn't catch sector numbers that are too high.
2018-02-23 16:12:12 -05:00

179 lines
3.8 KiB
ArmAsm

;
; 2001-07-02, Maciej 'YTM/Elysium' Witkowiak
; 2015-08-27, Greg King
;
; unsigned char __fastcall__ dio_log_to_phys (dhandle_t handle,
; unsigned *sectnum, /* input */
; dio_phys_pos *physpos); /* output */
;
.export _dio_log_to_phys
.importzp ptr1,ptr2,ptr3,tmp1,tmp2
.import popax,__oserror
.import sectab_1541_l, sectab_1541_h
.include "dio.inc"
.include "geossym.inc"
.include "const.inc"
_dio_log_to_phys:
; check device type
sta ptr1
stx ptr1+1 ; pointer to result (struct dio_phys_pos)
jsr popax
sta ptr2
stx ptr2+1 ; pointer to input structure (pointer to int)
jsr popax
sta ptr3
stx ptr3+1 ; pointer to handle
ldy #sst_flag
lda (ptr3),y
and #128
beq _inv_hand ; handle not open or invalid
; fill in all we have
ldy #diopp_head
lda #0 ; head 0
sta (ptr1),y
ldy #diopp_track+1
sta (ptr1),y ; track <256
ldy #diopp_sector+1
sta (ptr1),y ; sector <256
ldy #0
lda (ptr2),y
sta tmp1
iny
lda (ptr2),y
sta tmp2
; get drive info
ldy #sst_driveno
lda (ptr3),y
tay
lda driveType,y
and #%00001111 ; remove ramDisk flags
cmp #DRV_1541
beq dio_stc1541
cmp #DRV_1571
beq dio_stc1571
cmp #DRV_1581
beq dio_stc1581
lda #INCOMPATIBLE ; unsupported device
ldx #0
beq _ret
dio_stcend:
ldy #diopp_track
lda tmp1
sta (ptr1),y
ldy #diopp_sector
lda tmp2
sta (ptr1),y
ldx #0
txa
_ret:
sta __oserror
rts ; return success
; errors
_inv_data:
lda #INV_TRACK
.byte $2c
_inv_hand:
lda #DEV_NOT_FOUND
ldx #0
beq _ret
dio_stc1541:
; if 1541:
; - compare with table to find track
; - subtract and find sector
ldx #0 ; index=(track-1)
_loop41:
lda tmp2
cmp sectab_1541_h+1,x
bne _nxt
lda tmp1
cmp sectab_1541_l+1,x
_nxt: bcc _found
inx
cpx #35
bne _loop41
beq _inv_data
_found:
lda tmp1
sec
sbc sectab_1541_l,x
sta tmp2
_fndend:
inx
stx tmp1
jmp dio_stcend
dio_stc1571:
; if 1571:
; - check size, if too big - subtract and add 35 to track
; - fall down to 1541
lda tmp2
cmp #>683
bne _if71
lda tmp1
cmp #<683
_if71: bcc dio_stc1541
lda tmp1
sec
sbc #<683
sta tmp1
lda tmp2
sbc #>683
sta tmp2
jsr dio_stc1541 ; will fall through here
tay
bne _ret ; result beyond track 70
ldy #diopp_track
lda (ptr1),y
clc
adc #35
sta (ptr1),y
lda #0
beq _ret
; if 1581:
; - subtract 40 in loop (at most 80 times) to find track
; - the remainder is sector
dio_stc1581:
ldx #0 ; index=(track-1)
_loop81:
lda tmp2
bne _sub81
lda tmp1
cmp #40
bcc _got81
_sub81: lda tmp1
sec
sbc #40
sta tmp1
lda tmp2
sbc #0
sta tmp2
inx
cpx #80
bne _loop81
beq _inv_data
_got81: lda tmp1
sta tmp2
inx
stx tmp1
jmp dio_stcend