ported more MEGA65 SD card support code

src/aliases/,aliases_hardware_m65.s

@@ -32,6 +32,12 @@
 	!addr C65_EXTKEYS_PR  = $D607
 	!addr C65_EXTKEYS_DDR = $D608
 
+	; SD card
+
+	!addr SD_CTL          = $D680
+	!addr SD_ADDR         = $D681 ; 4 bytes
+	!addr SD_ERRCODE      = $D6DA
+
 	; DMAgic
 
 	!addr DMA_ADDRLSBTRIG = $D700

src/dos_m65/m65_sdcard.s

@@ -18,33 +18,21 @@
 !addr TMP_STEP     = $89  ; 4 bytes
 
 
-; Hardware
-
-!addr SD_CTL       = $D680
-!addr SD_ADDR      = $D681 ; 4 bytes
-!addr SD_ERRCODE   = $D6DA
-
-
-; XXX SD_SECTORBUF = 0xffd6e00L;
+; XXX hardware address SD_SECTORBUF = 0xffd6e00L;
 
 
 
 
 
 
-m65_sdcard_init: ; to be called during DOS initialization
+m65_sdcard_init:
 
 	lda #$00
 	sta CARD_IS_SDHC
 
 	jsr m65_sdcard_reset
 	
-	; FALLTROUGH
-
-m65_sdcard_init_gettype:
-
-	; First work out if this is SD or SDHC card
-	; SD cards can't read at non-sector aligned addresses
+	; Try to read first sector to see if card is operable
 
 	lda #$00
 	sta SD_ADDR+0
@@ -52,22 +40,67 @@ m65_sdcard_init_gettype:
 	sta SD_ADDR+2
 	sta SD_ADDR+3
 
-	; Trigger read
+	jsr m65_sdcard_read
+	bcc m65_sdcard_init_operable
+
+	; XXX if we are here, mark card as not operable and quit
+
+m65_sdcard_init_operable:
+
+	; Work out if this is SD or SDHC card - SD cards can't read at non-sector aligned addresses
 
 	lda #$02
-	sta SD_CTL
-
-	; XXX
+	sta SD_ADDR+0
+	lda #$00
+	sta SD_ADDR+1
+	sta SD_ADDR+2
+	sta SD_ADDR+3	
 
+	jsr m65_sdcard_read
 
+	lda SD_CTL
+	beq m65_sdcard_init_sdsc
 
 	; FALLTROUGH
 
-m65_sdcard_init_getsize:
+m65_sdcard_init_sdhc:
 
-	; Put $00200000 to TMP_STEP and TMP_SECNUM
+	lda #$80
+	sta CARD_IS_SDHC
 
-	; XXX this should probably be initialized in a loop
+	; Prepare data for determining card size - put $00200000 to TMP_STEP and TMP_SECNUM
+
+    ; SDHC claims 32GB limit, and reading from beyond that might cause
+    ; trouble. However, 32bits x 512byte sectors = 16TB addressable.
+    ; It thus seems that the top byte of the address may not be safe to use,
+    ; or at least the top few bits.
+
+	; XXX this should be initialized to 0 in a loop
+
+	lda #$00
+	sta TMP_SECNUM+0
+	sta TMP_STEP+0
+	sta TMP_SECNUM+1
+	sta TMP_STEP+1
+	sta TMP_SECNUM+2
+	sta TMP_STEP+2
+
+	lda #$02
+	sta TMP_SECNUM+3
+	sta TMP_STEP+3
+
+	bra m65_sdcard_init_getsize
+
+m65_sdcard_init_sdsc:
+
+	lda #$00
+	sta CARD_IS_SDHC
+	lda #$40                           ; use byte addressing
+	sta SD_CTL
+
+	; Prepare data for determining card size - put $00200000 to TMP_STEP and TMP_SECNUM
+
+	; XXX this should be initialized to 0 in a loop
 
 	lda #$00
 	sta TMP_SECNUM+0
@@ -81,7 +114,55 @@ m65_sdcard_init_getsize:
 	sta TMP_SECNUM+2
 	sta TMP_STEP+2
 
-	;; XXX finish
+	; FALLTROUGH
+
+m65_sdcard_init_getsize:
+
+	; Work out size of SD card in a safe way
+	; (binary search of sector numbers is NOT safe for some reason.
+	; It frequently reports bigger than the size of the card)
+
+	; XXX finish
+
+
+
+
+
+
+
+
+
+
+
+
+
+m65_sdcard_read:
+
+	; Trigger read
+
+	lda #$02
+	sta SD_CTL
+
+	; Wait for result
+
+	ldx #90
+@1:
+	jsr m65_sdcard_wait_16000_usec
+	lda SD_CTL
+	and #$03
+	beq @2
+	dex
+	bne @1
+
+	; Read failed
+
+	sec
+	rts
+@2:
+	;; Success
+
+	clc
+	rts
 
 
 
@@ -97,16 +178,42 @@ m65_sdcard_reset:
 	sty SD_CTL
 
 	; Wait till SD card resets
-@1:
+@3:
 	lda SD_CTL
 	and #$03
-	bne @1
+	bne @3
 
 	; For SDHC card set appropriate mode
 	
 	bit CARD_IS_SDHC
-	bpl @2
+	bpl @4
 	inx ; $41
 	stx SD_CTL
-@2:
+@4:
+	rts
+
+
+
+m65_sdcard_wait_16000_usec:
+
+	; Uses VIC-II raster register; wait time is not exactly precise, but should be
+	; a good approximation
+
+	phx
+	pha
+
+	ldx #$FF
+
+	; XXX wait below is same as in KKERNAL, wait_x_lines - consider importing and reusing
+	lda VIC_RASTER
+@w1:
+	cmp VIC_RASTER
+	beq @w1
+	lda VIC_RASTER
+	dex
+	bne @w1
+
+	pla
+	plx
+
 	rts

src/kernal/iec/iec_wait1ms.s

@@ -23,7 +23,7 @@ iec_wait1ms:
 
 	; FALLTROUGH
 
-wait_x_bars: ; additional entry point for delayy in screen and tape support
+wait_x_bars: ; additional entry point for delay in screen and tape support
              ; has to preserve .Y and put .X to 0
 
 	lda VIC_RASTER