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drv/sdc: implement "SDC@"

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I can read a block from blkfs in RC2014 emulator. It even checks
CRC16 successfully!
This commit is contained in:
Virgil Dupras 2020-04-18 14:22:26 -04:00
parent c64a8a2e2b
commit 052c744000
1 changed files with 40 additions and 1 deletions
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41
drv/sdc.fs
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@ -50,6 +50,18 @@
LOOP 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 ) ( send-and-crc7 )
( n c -- c ) ( n c -- c )
: _s+crc SWAP DUP _sdcSR DROP _crc7 ; : _s+crc SWAP DUP _sdcSR DROP _crc7 ;
@ -100,7 +112,7 @@
( Initialize a SD card. This should be called at least 1ms ( Initialize a SD card. This should be called at least 1ms
after the powering up of the card. r is result. after the powering up of the card. r is result.
Zero means success, non-zero means error. ) Zero means success, non-zero means error. )
: SDCINIT : SDC$
( Wake the SD card up. After power up, a SD card has to ( 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 receive at least 74 dummy clocks with CS and DI high. We
send 80. ) send 80. )
@ -143,3 +155,30 @@
( Out of idle mode! Success! ) ( Out of idle mode! Success! )
0 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 )
;