drv/sdc: implement "SDC@"

I can read a block from blkfs in RC2014 emulator. It even checks
CRC16 successfully!

blk/018

@@ -5,7 +5,7 @@ unsigned. For convenience, decimal parsing and formatting
 support the "-" prefix, but under the hood, it's all unsigned.
 
 This leads to some oddities. For example, "-1 0 <" is false.
-To compare whether something is negative, use the "<0" word
+To compare whether something is negative, use the "0<" word
 which is the equivalent to "0x7fff >".
 
 

blk/043

@@ -11,6 +11,6 @@ ABORT" x" --   *I* Compiles a ." followed by a ABORT.
 EXECUTE   a -- Execute wordref at addr a
 INTERPRET --   Get a line from stdin, compile it in tmp memory,
                then execute the compiled contents.
+LEAVE     --   In a DO..LOOP, exit at the next LOOP call.
 QUIT      --   Return to interpreter prompt immediately
 EXIT!     --   Exit current INTERPRET loop.
-

drv/sdc.fs

@@ -0,0 +1,184 @@
+: SDC_CSHIGH 6 ;
+: SDC_CSLOW 5 ;
+: SDC_SPI 4 ;
+
+: _sdcSR SDC_SPI PC! SDC_SPI PC@ ;
+
+: _sel 0 SDC_CSLOW PC! ;
+: _desel 0 SDC_CSHIGH PC! ;
+
+( -- n )
+: _idle 0xff _sdcSR ;
+
+( -- n )
+( _sdcSR 0xff until the response is something else than 0xff
+  for a maximum of 20 times. Returns 0xff if no response. )
+: _wait
+    0  ( cnt )
+    BEGIN
+        _idle
+        DUP 0xff = IF DROP ELSE SWAP DROP EXIT THEN
+        1+
+    DUP 20 = UNTIL
+    DROP 0xff
+;
+
+( -- )
+( The opposite of sdcWaitResp: we wait until response is 0xff.
+  After a successful read or write operation, the card will be
+  busy for a while. We need to give it time before interacting
+  with it again. Technically, we could continue processing on
+  our side while the card it busy, and maybe we will one day,
+  but at the moment, I'm having random write errors if I don't
+  do this right after a write, so I prefer to stay cautious
+  for now. )
+: _ready BEGIN _idle 0xff = UNTIL ;
+
+( c n -- c )
+( Computes n into crc c with polynomial 0x09
+  Note that the result is "left aligned", that is, that 8th
+  bit to the "right" is insignificant (will be stop bit). )
+: _crc7
+    XOR           ( c )
+    8 0 DO
+        2 *       ( <<1 )
+        DUP 255 > IF
+            ( MSB was set, apply polynomial )
+            0xff AND
+            0x12 XOR  ( 0x09 << 1, we apply CRC on high bits )
+        THEN
+    LOOP
+;
+
+( c n -- c )
+( Computes n into crc c with polynomial 0x1021 )
+: _crc16
+    SWAP DUP 256 /    ( n c c>>8 )
+    ROT XOR           ( c x )
+    DUP 16 / XOR      ( c x^x>>4 )
+    SWAP 256 *        ( x c<<8 )
+    OVER 4096 * XOR   ( x c^x<<12 )
+    OVER 32 * XOR     ( x c^x<<5 )
+    XOR               ( c )
+;
+
+( send-and-crc7 )
+( n c -- c )
+: _s+crc SWAP DUP _sdcSR DROP _crc7 ;
+
+( cmd arg1 arg2 -- resp )
+( Sends a command to the SD card, along with arguments and
+  specified CRC fields. (CRC is only needed in initial commands
+  though).
+  This does *not* handle CS. You have to select/deselect the
+  card outside this routine. )
+: _cmd
+    _wait DROP
+    ROT            ( a1 a2 cmd )
+    0 _s+crc       ( a1 a2 crc )
+    ROT 256 /MOD   ( a2 crc h l )
+    ROT            ( a2 h l crc )
+    _s+crc         ( a2 h crc )
+    _s+crc         ( a2 crc )
+    SWAP 256 /MOD  ( crc h l )
+    ROT            ( h l crc )
+    _s+crc         ( h crc )
+    _s+crc         ( crc )
+    ( send CRC )
+    0x01 OR        ( ensure stop bit )
+    _sdcSR DROP
+	( And now we just have to wait for a valid response... )
+    _wait
+;
+
+( cmd arg1 arg2 -- r )
+( Send a command that expects a R1 response, handling CS. )
+: SDCMDR1 _sel _cmd _desel ;
+
+( cmd arg1 arg2 -- r arg1 arg2 )
+( Send a command that expects a R7 response, handling CS. A R7
+  is a R1 followed by 4 bytes. arg1 contains bytes 0:1, arg2
+  has 2:3 )
+: SDCMDR7
+    _sel
+    _cmd        ( r )
+    _idle 256 * ( r h )
+    _idle +     ( r arg1 )
+    _idle 256 * ( r arg1 h )
+    _idle +     ( r arg1 arg2 )
+    _desel
+;
+
+( Initialize a SD card. This should be called at least 1ms
+  after the powering up of the card. r is result.
+  Zero means success, non-zero means error. )
+: SDC$
+    ( Wake the SD card up. After power up, a SD card has to
+      receive at least 74 dummy clocks with CS and DI high. We
+      send 80. )
+    10 0 DO 0xff SDC_SPI PC! LOOP
+
+	( call cmd0 and expect a 0x01 response (card idle)
+	  this should be called multiple times. we're actually
+      expected to. let's call this for a maximum of 10 times. )
+    0  ( dummy )
+    10 0 DO  ( r )
+        DROP
+        0b01000000 0 0  ( CMD0 )
+        SDCMDR1
+        DUP 0x01 = IF LEAVE THEN
+    LOOP
+    0x01 = NOT IF 1 EXIT THEN
+
+	( Then comes the CMD8. We send it with a 0x01aa argument
+      and expect a 0x01aa argument back, along with a 0x01 R1
+      response. )
+    0b01001000 0 0x1aa  ( CMD8 )
+    SDCMDR7                     ( r arg1 arg2 )
+    0x1aa = NOT IF 2 EXIT THEN  ( arg2 check )
+    0 = NOT IF 3 EXIT THEN      ( arg1 check )
+    0x01 = NOT IF 4 EXIT THEN   ( r check )
+
+	( Now we need to repeatedly run CMD55+CMD41 (0x40000000)
+      until 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. )
+    BEGIN
+        0b01110111 0 0  ( CMD55 )
+        SDCMDR1
+        0x01 = NOT IF 5 EXIT THEN
+        0b01101001 0x4000 0x0000  ( CMD41 )
+        SDCMDR1
+        DUP 0x01 > IF DROP 6 EXIT THEN
+    NOT UNTIL
+    ( Out of idle mode! Success! )
+    0
+;
+
+( dstaddr blkno -- f )
+: SDC@
+    _sel
+    0x51    ( CMD17 )
+    0 ROT   ( a cmd 0 blkno )
+    _cmd
+    IF _desel 0 EXIT THEN
+    _wait
+    0xfe = NOT IF _desel 0 EXIT THEN
+    0 SWAP           ( crc a )
+    512 0 DO         ( crc a )
+        DUP          ( crc a a )
+        _idle        ( crc a a n )
+        DUP ROT      ( crc a n n a )
+        C!           ( crc a n )
+        ROT SWAP     ( a crc n )
+        _crc16       ( a crc )
+        SWAP 1+      ( crc a+1 )
+    LOOP
+    DROP             ( crc1 )
+    _idle 256 *
+    _idle +          ( crc2 )
+    _wait DROP
+    _desel
+    =   ( success if crc1 == crc2 )
+;

emul/hw/rc2014/sdc.c

@@ -122,6 +122,7 @@ void sdc_spi_wr(SDC *sdc, uint8_t val)
     uint8_t cmd = b[0] & 0x3f;
     uint16_t arg1 = (b[1] << 8) | b[2];
     uint16_t arg2 = (b[3] << 8) | b[4];
+    // printf("cmd %02x %04x %04x\n", cmd, arg1, arg2);
     if (sdc->initstat == 8) {
         // At this stage, we're expecting CMD0
         if (cmd == 0) {

forth/cmp.fs

@@ -2,8 +2,7 @@
 
 : >= < NOT ;
 : <= > NOT ;
-: <0 32767 > ;
-: >=0 <0 NOT ;
+: 0>= 0< NOT ;
 
 ( n1 -- n1 true )
 : <>{ 1 ;

forth/core.fs

@@ -133,6 +133,8 @@
     COMPILE R> COMPILE DROP COMPILE R> COMPILE DROP
 ; IMMEDIATE
 
+: LEAVE R> R> DROP I 1- >R >R ;
+
 ( a1 a2 u -- )
 : MOVE
     ( u ) 0 DO

forth/fmt.fs

@@ -12,7 +12,7 @@
 
 : .               ( n -- )
     ( handle negative )
-    DUP <0 IF '-' EMIT -1 * THEN
+    DUP 0< IF '-' EMIT -1 * THEN
     _
     BEGIN
     DUP '9' > IF DROP EXIT THEN  ( stop indicator, we're done )

forth/icore.fs

@@ -51,6 +51,7 @@
 : = CMP NOT ;
 : < CMP -1 = ;
 : > CMP 1 = ;
+: 0< 32767 > ;
 
 ( r c -- r f )
 ( Parse digit c and accumulate into result r.
@@ -61,7 +62,7 @@
     ( parse char )
     '0' -
     ( if bad, return "r -1" )
-    DUP 0 < IF DROP -1 EXIT THEN   ( bad )
+    DUP 0< IF DROP -1 EXIT THEN    ( bad )
     DUP 9 > IF DROP -1 EXIT THEN   ( bad )
     ( good, add to running result )
     SWAP 10 * +                    ( r*10+n )

forth/parse.fs

@@ -11,14 +11,14 @@
 ;
 
 ( returns negative value on error )
-: hexdig            ( c -- n )
+: _            ( c -- n )
     ( '0' is ASCII 48 )
     48 -
-    DUP 0 < IF EXIT THEN                ( bad )
+    DUP 0< IF EXIT THEN                 ( bad )
     DUP 10 < IF EXIT THEN               ( good )
     ( 'a' is ASCII 97. 59 = 97 - 48 )
     49 -
-    DUP 0 < IF EXIT THEN                ( bad )
+    DUP 0< IF EXIT THEN                 ( bad )
     DUP 6 < IF 10 + EXIT THEN           ( good )
     ( bad )
     255 -
@@ -31,24 +31,23 @@
     2+
     ( validate slen )
     DUP SLEN                            ( a l )
-    DUP 0 = IF DROP 0 EXIT THEN         ( a 0 )
+    DUP NOT IF DROP 0 EXIT THEN         ( a 0 )
     4 > IF DROP 0 EXIT THEN             ( a 0 )
-    0 ( a r )
+    0  ( a r )
     BEGIN
-    OVER C@
-    DUP 0 = IF DROP SWAP DROP 1 EXIT THEN ( r, 1 )
-    hexdig                              ( a r n )
-    DUP 0 < IF DROP DROP 1 EXIT THEN    ( a 0 )
-    SWAP 16 * +                         ( a r*16+n )
-    SWAP 1+ SWAP                        ( a+1 r )
+    SWAP C@+                            ( r a+1 c )
+    DUP NOT IF 2DROP 1 EXIT THEN        ( r, 1 )
+    _                                   ( r a n )
+    DUP 0< IF ROT 2DROP 0 EXIT THEN     ( a 0 )
+    ROT 16 * +                          ( a r*16+n )
     AGAIN
 ;
 
 ( returns negative value on error )
-: bindig            ( c -- n )
+: _            ( c -- n )
     ( '0' is ASCII 48 )
     48 -
-    DUP 0 < IF EXIT THEN                ( bad )
+    DUP 0< IF EXIT THEN                 ( bad )
     DUP 2 < IF EXIT THEN                ( good )
     ( bad )
     255 -
@@ -65,12 +64,11 @@
     16 > IF DROP 0 EXIT THEN            ( a 0 )
     0 ( a r )
     BEGIN
-    OVER C@
-    DUP 0 = IF DROP SWAP DROP 1 EXIT THEN ( r, 1 )
-    bindig                              ( a r n )
-    DUP 0 < IF DROP DROP 1 EXIT THEN    ( a 0 )
-    SWAP 2 * +                          ( a r*2+n )
-    SWAP 1+ SWAP                        ( a+1 r )
+    SWAP C@+                               ( r a+1 c )
+    DUP NOT IF 2DROP 1 EXIT THEN           ( r 1 )
+    _                                      ( r a n )
+    DUP 0< IF ROT 2DROP 0 EXIT THEN        ( a 0 )
+    ROT 2 * +                              ( a r*2+n )
     AGAIN
 ;