sdc: enable CRC checks on blk write

This commit is contained in:
Virgil Dupras 2019-06-19 09:00:50 -04:00
parent 6df77ddef3
commit d9ae82c81e

View File

@ -315,22 +315,6 @@ sdcInitialize:
pop hl
ret
; Send a command to set block size to SDC_BLKSIZE to the SD card.
; Returns zero in A if a success, non-zero otherwise
sdcSetBlkSize:
push hl
push de
ld a, 0b01010000 ; CMD16
ld hl, 0
ld de, SDC_BLKSIZE
call sdcCmdR1
; Since we're out of idle mode, we expect a 0 response
; We need no further processing: A is already the correct value.
pop de
pop hl
ret
; Read block index specified in DE and place the contents in buffer pointed to
; by (SDC_BUFPTR).
; If the operation is a success, updates buffer's sector to the value of DE.
@ -433,28 +417,32 @@ sdcReadBlk:
; Write the contents of buffer where (SDC_BUFPTR) points to in sector associated
; to it. Unsets the the buffer's dirty flag on success.
; Before writing the block, update the buffer's CRC field so that the correct
; CRC is sent.
; A returns 0 in A on success (with Z set), non-zero (with Z unset) on error.
sdcWriteBlk:
push hl
ld hl, (SDC_BUFPTR) ; HL points to sector LSB
inc hl ; sector MSB
inc hl ; now to dirty flag
push ix
ld ix, (SDC_BUFPTR) ; HL points to sector LSB
xor a
cp (hl)
cp (ix+2) ; dirty flag
jr z, .dontWrite ; A is already 0
; At this point, HL points to dirty flag of the proper buffer
push bc
push de
push hl
call sdcCRC ; DE -> new CRC. HL -> pointer to buf CRC
ld a, d ; write computed CRC
ld (hl), a
inc hl
ld a, e
ld (hl), a
out (SDC_PORT_CSLOW), a
dec hl ; sector MSB
ld a, (hl)
ld d, a
dec hl ; sector LSB
ld a, (hl)
ld a, (ix) ; sector LSB
ld e, a
ld a, (ix+1) ; sector MSB
ld d, a
ld hl, 0 ; high addr word always zero, DE already set
ld a, 0b01011000 ; CMD24
call sdcCmd
@ -463,8 +451,7 @@ sdcWriteBlk:
; Before sending the data packet, we need to send at least one empty
; byte.
ld a, 0xff
call sdcSendRecv
call sdcIdle
; data packet token for CMD24
ld a, 0xfe
@ -513,10 +500,11 @@ sdcWriteBlk:
inc a ; zero, adjust
.end:
out (SDC_PORT_CSHIGH), a
pop hl
pop de
pop bc
.dontWrite:
pop hl
pop ix
ret
; Considering the first 15 bits of EHL, select the most appropriate of our two
@ -645,7 +633,9 @@ sdcInitializeCmd:
.db "sdci", 0, 0, 0
call sdcInitialize
ret nz
call sdcSetBlkSize
call .setBlkSize
ret nz
call .enableCRC
ret nz
; At this point, our buffers are unnitialized. We could have some logic
; that determines whether a buffer is initialized in appropriate SDC
@ -663,6 +653,35 @@ sdcInitializeCmd:
inc de
jp sdcReadBlk ; read sector 1 in buf2, returns
; Send a command to set block size to SDC_BLKSIZE to the SD card.
; Returns zero in A if a success, non-zero otherwise
.setBlkSize:
push hl
push de
ld a, 0b01010000 ; CMD16
ld hl, 0
ld de, SDC_BLKSIZE
call sdcCmdR1
; Since we're out of idle mode, we expect a 0 response
; We need no further processing: A is already the correct value.
pop de
pop hl
ret
; Enable CRC checks through CMD59
.enableCRC:
push hl
push de
ld a, 0b01111011 ; CMD59
ld hl, 0
ld de, 1 ; 1 means CRC enabled
call sdcCmdR1
pop de
pop hl
ret
; Flush the current SDC buffer if dirty
sdcFlushCmd:
.db "sdcf", 0, 0, 0