recipe/rc2014/sdcard: we read data!

recipes/rc2014/sdcard/README.md

@@ -83,9 +83,19 @@ the block creation part.
 
 ## Testing CD card initialization
 
-To test that you can properly initialize a SD card, you can compile this [user
-program](sdinit.asm) (see [Makefile](Makefile)) and then
-[run it from memory][run-from-mem]. Success means the card is initialized.
+This receipes contains a little [user program](sdinit.asm) that initializes a
+SD card, reads the first 12 bytes from its first sector and prints it.
+
+The first thing we'll do is fill the SD card's first 12 bytes with "Hello
+World!":
+
+    echo "Hello World!" > /dev/sdX
+
+Then, you can run `make` from within this folder to compile `sdinit.bin` and
+then [upload and run][run-from-mem] that code from memory. You might need to
+call the routine more than once (On my local tests, I need to call it twice).
+
+If all goes well, you should see your "Hello World!" printed to the console!
 
 ## Create a block device from the SD card reader
 

recipes/rc2014/sdcard/sdinit.asm

@@ -4,7 +4,7 @@
 	call	JUMP_SDCWAKEUP
 
 	; We expect a 0x01 R1 response
-	ld	hl, sCmd0
+	ld	hl, sCmd
 	call	JUMP_PRINTSTR
 	ld	a, 0b01000000	; CMD0
 	ld	hl, 0
@@ -12,27 +12,21 @@
 	ld	c, 0x95
 	call	JUMP_SDCCMDR1
 	cp	0x01
-	jr	nz, .error
+	jp	nz, .error
 	ld	hl, sOk
 	call	JUMP_PRINTSTR
 
 	; We expect a 0x01 R1 response followed by 0x0001aa R7 response
-	ld	hl, sCmd8
+	ld	hl, sCmd
 	call	JUMP_PRINTSTR
 	ld	a, 0b01001000	; CMD8
 	ld	hl, 0
 	ld	de, 0x01aa
 	ld	c, 0x87
 	call	JUMP_SDCCMDR7
-	ld	a, h
-	cp	0
-	jr	nz, .error
-	ld	a, l
-	cp	0
-	jr	nz, .error
 	ld	a, d
 	cp	0x01
-	jr	nz, .error
+	jp	nz, .error
 	ld	a, e
 	cp	0xaa
 	jr	nz, .error
@@ -43,9 +37,9 @@
 	; the card goes out of idle mode, that is, when it stops sending us
 	; 0x01 response and send us 0x00 instead. Any other response means that
 	; initialization failed.
-	ld	hl, sCmd41
+	ld	hl, sCmd
 	call	JUMP_PRINTSTR
-.loop:
+.loop1:
 	ld	a, 0b01110111	; CMD55
 	ld	hl, 0
 	ld	de, 0
@@ -57,25 +51,73 @@
 	ld	de, 0x0000
 	call	JUMP_SDCCMDR1
 	cp	0x01
-	jr	z, .loop
+	jr	z, .loop1
 	cp	0
 	jr	nz, .error
 	; Success! out of idle mode!
 	ld	hl, sOk
 	call	JUMP_PRINTSTR
+
+	; Alright, normally we should configure block size and all, but this is
+	; too exciting and we'll play it dirty: we'll read just enough bytes
+	; to fetch our "Hello World!" and print it and we'll leave the SD card
+	; hanging. Yeah, I know, not very polite.
+
+
+	out	(5), a
+	ld	hl, sCmd
+	call	JUMP_PRINTSTR
+	ld	a, 0b01010001	; CMD17
+	ld	hl, 0		; read single block at addr 0
+	ld	de, 0
+	call	JUMP_SDCCMD
+	cp	0
+	jr	nz, .error
+
+	ld	hl, sCmd
+	call	JUMP_PRINTSTR
+	; Command sent, no error, now let's wait for our data response.
+	ld	b, 20
+.loop3:
+	call	JUMP_SDCWAITRESP
+	; 0xfe is the expected data token for CMD17
+	cp	0xfe
+	jr	z, .loop3end
+	cp	0xff
+	jr	nz, .error
+	djnz	.loop3
+	jr	.error
+
+.loop3end:
+	ld	hl, sGettingData
+	call	JUMP_PRINTSTR
+	; Data packets follow immediately
+	ld	b, 12		; size of "Hello World!"
+	ld	hl, sDest	; sDest has null chars, we'll be alright
+				; printing it.
+.loop2:
+	call	JUMP_SDCWAITRESP
+	ld	(hl), a
+	inc	hl
+	djnz	.loop2
+	out	(6), a
+	ld	hl, sDest
+	call	JUMP_PRINTSTR
 	ret
 .error:
+	call	JUMP_PRINTHEX
 	ld	hl, sErr
 	call	JUMP_PRINTSTR
 	ret
 
-sCmd0:
-	.db "Sending CMD0", 0xa, 0xd, 0
-sCmd8:
-	.db "Sending CMD8", 0xa, 0xd, 0
-sCmd41:
-	.db "Sending CMD41", 0xa, 0xd, 0
+sCmd:
+	.db "CMD", 0xa, 0xd, 0
+sGettingData:
+	.db "Data", 0xa, 0xd, 0
 sOk:
 	.db "Ok", 0xa, 0xd, 0
 sErr:
 	.db "Err", 0xa, 0xd, 0
+
+sDest:
+	.fill 0x10