99 lines
1.1 KiB
ArmAsm
99 lines
1.1 KiB
ArmAsm
|
|
;
|
|
; Reads the sector from the SD card
|
|
;
|
|
|
|
; Based on https://github.com/MEGA65/mega65-libc/blob/master/cc65/src/sdcard.c
|
|
|
|
|
|
; XXX provide documentation
|
|
|
|
|
|
sdcard_readsector:
|
|
|
|
; XXX check if card initialized and operable
|
|
|
|
; Set read address
|
|
|
|
jsr sdcard_set_addr
|
|
bcs sdcard_readsector_fail
|
|
|
|
; FALLTROUGH
|
|
|
|
sdcard_readsector_read:
|
|
|
|
; Set number of retries
|
|
|
|
lda #$0A
|
|
sta CARD_TMP_RETRIES
|
|
|
|
; FALLTROUGH
|
|
|
|
sdcard_readsector_try_loop:
|
|
|
|
; Wait till card is ready
|
|
|
|
jsr sdcard_wait_ready
|
|
bcs sdcard_readsector_fail
|
|
|
|
; Read command
|
|
|
|
lda #$02
|
|
sta SD_CTL
|
|
|
|
; Wait for command completion
|
|
|
|
jsr sdcard_wait_ready
|
|
bcs sdcard_readsector_fail
|
|
|
|
|
|
lda SD_CTL
|
|
and #$67
|
|
bne sdcard_readsector_copy_data
|
|
|
|
jsr sdcard_reset
|
|
dec CARD_TMP_RETRIES
|
|
bne sdcard_readsector_try_loop
|
|
|
|
; FALLTROUGH
|
|
|
|
sdcard_readsector_fail:
|
|
|
|
sec
|
|
rts
|
|
|
|
|
|
;
|
|
; Helper routines
|
|
;
|
|
|
|
sdcard_readsector_copy_data:
|
|
|
|
; XXX use DMAgic for this
|
|
|
|
phz
|
|
phx
|
|
|
|
ldx #$00
|
|
ldz #$00
|
|
|
|
@1:
|
|
lda [CARD_BUFPNT],z
|
|
sta CARD_BUF,x
|
|
inc CARD_BUFPNT+1
|
|
lda [CARD_BUFPNT],z
|
|
sta CARD_BUF+$100,x
|
|
dec CARD_BUFPNT+1
|
|
|
|
inz
|
|
inx
|
|
bne @1
|
|
|
|
; Restore registers and quit
|
|
|
|
plx
|
|
plz
|
|
|
|
clc
|
|
rts
|