drv/sdc: Implement SDC!

This has been tested in the RC2014 emulator. I could edit blocks with
the Block Editor and they would correctly be written to SDC.

drv/sdc.fs

@@ -156,10 +156,7 @@
     0
 ;
 
-: _err
-    _desel
-    ABORT" SDC error"
-;
+: _err _desel ABORT" SDerr" ;
 
 ( dstaddr blkno -- )
 : _sdc@
@@ -194,3 +191,36 @@
     1+ BLK( 512 + SWAP
     _sdc@
 ;
+
+( srcaddr blkno -- )
+: _sdc!
+    _sel
+    0x58    ( CMD24 )
+    0 ROT   ( a cmd 0 blkno )
+    _cmd
+    IF _err THEN
+    _idle DROP
+    0xfe _sdcSR DROP
+    0 SWAP           ( crc a )
+    512 0 DO         ( crc a )
+        C@+          ( crc a+1 n )
+        ROT OVER     ( a n crc n )
+        _crc16       ( a n crc )
+        SWAP         ( a crc n )
+        _sdcSR DROP  ( a crc )
+        SWAP         ( crc a )
+    LOOP
+    DROP             ( crc )
+    256 /MOD         ( lsb msb )
+    _sdcSR DROP      ( lsb )
+    _sdcSR DROP
+    _wait DROP
+    _desel
+;
+
+: SDC!
+    2 * DUP BLK( SWAP    ( b a b )
+    _sdc!
+    1+ BLK( 512 + SWAP
+    _sdc!
+;

emul/hw/rc2014/sdc.c

@@ -183,7 +183,6 @@ void sdc_spi_wr(SDC *sdc, uint8_t val)
         return;
     }
     if (cmd == 24) {
-        fprintf(stderr, "cmd24\n");
         if (sdc->fp) {
             fseek(sdc->fp, arg2*512, SEEK_SET);
         }