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parts/z80/sdc: add sdcSetBlkSize and sdcReadBlk
This commit is contained in:
Virgil Dupras
parent
12ca2bd53e
commit
54d0286486
@ -20,6 +20,18 @@
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; SDC_PORT_CSLOW: Port number to make CS low
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; SDC_PORT_SPI: Port number to send/receive SPI data
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; *** Consts ***
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.equ SDC_BLKSIZE 512
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; *** Variables ***
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; Index of the sector currently contained in SDC_BUF
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.equ SDC_SECTOR SDC_RAMSTART
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; Whenever we read a sector, we read a whole block at once and we store it
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; in memory. That's where it goes.
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.equ SDC_BUF SDC_SECTOR+1
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.equ SDC_RAMEND SDC_BUF+SDC_BLKSIZE
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; *** Code ***
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; Wake the SD card up. After power up, a SD card has to receive at least 74
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; dummy clocks with CS and DI high. We send 80.
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sdcWakeUp:
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@ -199,7 +211,6 @@ sdcInitialize:
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or a ; cp 0
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jr nz, .error
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; Success! out of idle mode!
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; At this point, you are ready to read and write data.
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jr .success
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.error:
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@ -213,3 +224,74 @@ sdcInitialize:
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pop de
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pop hl
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ret
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; Send a command to set block size to SDC_BLKSIZE to the SD card.
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; Returns zero in A if a success, non-zero otherwise
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sdcSetBlkSize:
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push hl
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push de
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ld a, 0b01010000 ; CMD16
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ld hl, 0
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ld de, SDC_BLKSIZE
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call sdcCmdR1
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; Since we're out of idle mode, we expect a 0 response
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; We need no further processing: A is already the correct value.
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pop de
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pop hl
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ret
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; Read block index specified in A and place the contents in (SDC_BUF).
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; Doesn't check CRC.
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; Returns 0 in A if success, non-zero if error.
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; Returns SDC_BUF in HL
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sdcReadBlk:
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push bc
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out (SDC_PORT_CSLOW), a
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ld hl, 0 ; read single block at addr A
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ld d, 0
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ld e, a
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ld a, 0b01010001 ; CMD17
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call sdcCmd
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or a ; cp 0
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jr nz, .error
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; Command sent, no error, now let's wait for our data response.
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ld b, 20
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.loop1:
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call sdcWaitResp
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; 0xfe is the expected data token for CMD17
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cp 0xfe
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jr z, .loop1end
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cp 0xff
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jr nz, .error
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djnz .loop1
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jr .error ; timeout. error out
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.loop1end:
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; We received our data token!
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; Data packets follow immediately, we have 512 of them to read
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ld bc, SDC_BLKSIZE
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ld hl, SDC_BUF
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.loop2:
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call sdcWaitResp
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ld (hl), a
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cpi ; a trick to inc HL and dec BC at the same time.
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; P/V indicates whether BC reached 0
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jp pe, .loop2 ; BC is not zero, loop
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; Read our 2 CRC bytes
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call sdcWaitResp
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call sdcWaitResp
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; success!
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xor a
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jr .end
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.error:
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; try to preserve error code
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or a ; cp 0
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jr nz, .end ; already non-zero
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inc a ; zero, adjust
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.end:
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out (SDC_PORT_CSHIGH), a
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ld hl, SDC_BUF
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pop bc
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ret
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@ -17,6 +17,8 @@ jr init
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jp sdcCmd
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jp sdcCmdR1
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jp sdcCmdR7
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jp sdcReadBlk
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jp sdcSetBlkSize
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; interrupt hook
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.fill 0x38-$
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@ -57,6 +59,7 @@ SHELL_RAMSTART .equ BLOCKDEV_RAMEND
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SHELL_EXTRA_CMD_COUNT .equ 0
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#include "shell.asm"
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.equ SDC_RAMSTART SHELL_RAMEND
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.equ SDC_PORT_CSHIGH 6
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.equ SDC_PORT_CSLOW 5
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.equ SDC_PORT_SPI 4
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@ -6,4 +6,6 @@ JUMP_SDCWAITRESP .equ 0x0e
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JUMP_SDCCMD .equ 0x11
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JUMP_SDCCMDR1 .equ 0x14
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JUMP_SDCCMDR7 .equ 0x17
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JUMP_SDCREAD .equ 0x1a
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JUMP_SDCSETBLKSIZE .equ 0x1d
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@ -5,51 +5,30 @@
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or a
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jp nz, .error
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; Alright, normally we should configure block size and all, but this is
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; too exciting and we'll play it dirty: we'll read just enough bytes
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; to fetch our "Hello World!" and print it and we'll leave the SD card
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; hanging. Yeah, I know, not very polite.
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out (5), a
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ld hl, sCmd
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ld hl, sOk
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call JUMP_PRINTSTR
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ld a, 0b01010001 ; CMD17
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ld hl, 0 ; read single block at addr 0
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ld de, 0
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call JUMP_SDCCMD
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cp 0
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jr nz, .error
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ld hl, sCmd
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call JUMP_PRINTSTR
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; Command sent, no error, now let's wait for our data response.
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ld b, 20
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.loop1:
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call JUMP_SDCWAITRESP
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; 0xfe is the expected data token for CMD17
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cp 0xfe
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jr z, .loop1end
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cp 0xff
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jr nz, .error
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djnz .loop1
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jr .error
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call JUMP_SDCSETBLKSIZE
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or a
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jp nz, .error
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.loop1end:
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ld hl, sGettingData
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ld hl, sOk
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call JUMP_PRINTSTR
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; Data packets follow immediately
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ld b, 12 ; size of "Hello World!"
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ld hl, sDest ; sDest has null chars, we'll be alright
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; printing it.
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.loop2:
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call JUMP_SDCWAITRESP
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ld (hl), a
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inc hl
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djnz .loop2
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out (6), a
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ld hl, sDest
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; read sector 0
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xor a
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call JUMP_SDCREAD
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or a
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jp nz, .error
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push hl
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ld hl, sOk
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call JUMP_PRINTSTR
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pop hl
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; SDC buffer address is in HL
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; YOLO! print it!
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call JUMP_PRINTSTR
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ret
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.error:
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call JUMP_PRINTHEX
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@ -57,14 +36,7 @@
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call JUMP_PRINTSTR
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ret
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sCmd:
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.db "CMD", 0xa, 0xd, 0
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sGettingData:
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.db "Data", 0xa, 0xd, 0
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sOk:
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.db "Ok", 0xa, 0xd, 0
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sErr:
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.db "Err", 0xa, 0xd, 0
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sDest:
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.fill 0x10
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