Files
super6502/sw/bios/devices/sd_card_asm.s
2023-08-08 19:28:10 -07:00

303 lines
6.7 KiB
ArmAsm

.export _SD_command
.export _SD_readRes1
.export _SD_readRes2
.export _SD_readRes3
.export _SD_readRes7
.export _SD_readBytes
.export _SD_powerUpSeq
.export _res1_cmd
.export _SD_readSingleBlock
.importzp sp, ptr1, ptr2, ptr3, ptr4, tmp1, tmp2, tmp3
.autoimport on
.MACPACK generic
; void SD_command(uint8_t cmd, uint32_t arg, uint8_t crc)
; The plan: push crc to stack, load arg into tmp1 through 4
.proc _SD_command: near
pha ; Push CRC to cpu stack
ldy #$04
lda (sp),y ; Load CMD
ora #$40 ; start bit
jsr _spi_exchange
dey
arg_loop: ; send ARG
lda (sp),y ; is this sending only 3?
jsr _spi_exchange
dey
bpl arg_loop
pla ; Pull CRC from stack
ora #$01 ; stop bit
jsr _spi_exchange
jsr incsp5 ; pop all off stack
rts
.endproc
; uint8_t SD_readRes1 (void)
.proc _SD_readRes1: near
; Try to read/write up to 8 times, then return value
ldx #$08
tryread:
lda #$ff
jsr _spi_exchange
cmp #$ff
bne end
dex
bne tryread
end: ; x will be 0 here anyway
rts
.endproc
; void SD_readRes2(uint8_t *res)
.proc _SD_readRes2: near
sta ptr1 ; store res in ptr1
stx ptr1 + 1
jsr _SD_readRes1 ; get first response 1
sta (ptr1)
lda #$ff
jsr _spi_exchange ; get final byte of response
ldy #$01
sta (ptr1),y
jsr incsp2
rts
.endproc
; void SD_readBytes(uint8_t *res, uint8_t n)
.proc _SD_readBytes: near
tax
jsr popptr1 ; store res in ptr1
read:
lda #$ff ; read data first
jsr _spi_exchange
sta (ptr1)
inc ptr1 ; then increment res
bne @L1
inc ptr1 + 1
@L1: dex ; then decrement x
bne read ; and if x is zero we are done
rts
.endproc
; void SD_readRes7(uint8_t *res)
_SD_readRes7:
; void SD_readRes3(uint8_t *res)
.proc _SD_readRes3: near
sta ptr1 ; store res in ptr1
stx ptr1 + 1
jsr _SD_readRes1 ; read respopnse 1 in R3
cmp #$02 ; if error reading R1, return
bge @L1
inc ptr1 ; read remaining bytes
bne @L2
inc ptr1
@L2: lda ptr1 ; push low byte
ldx ptr1 + 1
jsr pushax
lda #$04 ; R3_BYTES
jsr _SD_readBytes
@L1: rts
.endproc
; uint8_t res1_cmd(uint8_t cmd, uint32_t arg, uint8_t crc)
.proc _res1_cmd: near
pha ; push crc to processor stack
lda #$ff
jsr _spi_exchange
lda #$00 ; this gets ignored anyway
jsr _spi_select
lda #$ff
jsr _spi_exchange
pla
jsr _SD_command ; rely on command to teardown stack
jsr _SD_readRes1
tay ; spi doesn't touch y
lda #$ff
jsr _spi_exchange
lda #$00 ; this gets ignored anyway
jsr _spi_deselect
lda #$ff
jsr _spi_exchange
tya
ldx #$00 ; Promote to integer
rts
.endproc
; void SD_powerUpSeq(void)
.proc _SD_powerUpSeq: near
lda #$00
jsr _spi_deselect
jsr _sd_delay
lda #$ff
jsr _spi_exchange
lda #$00
jsr _spi_deselect
ldx #$50 ; SD_INIT_CYCLES
@L1: lda #$ff
jsr _spi_exchange
dex
bne @L1
rts
.endproc
; 1ms delay approx. saves no registers
.proc _sd_delay: near
ldx #$01 ; delay loop: A*X*10 + 4
@L1: lda #$c8 ; 1ms at 2MHz
@L2: dec ; 2
bne @L2 ; 3
dex ; 2
bne @L1 ; 3
rts
.endproc
; ;uint8_t SD_readSingleBlock(uint32_t addr, uint8_t *buf, uint8_t *token)
.proc _SD_readSingleBlock: near
; token address in a/x
; buf address next on stack
; sd address above that
; ptr2 = *token
sta ptr2
stx ptr2 + 1
lda #$ff
sta (ptr2)
; ptr1 = *buf
jsr popptr1
; 4 bytes on stack are addr
; Move addr down on the stack
lda sp
sta ptr3
lda sp + 1
sta ptr3 + 1
; find a way to do this in a loop?
jsr decsp1
ldy #$0
lda (ptr3),y
sta (sp),y
iny
lda (ptr3),y
sta (sp),y
iny
lda (ptr3),y
sta (sp),y
iny
lda (ptr3),y
sta (sp),y
lda #$ff
jsr _spi_exchange
lda #$00 ; this gets ignored anyway
jsr _spi_select
lda #$ff
jsr _spi_exchange
; push cmd17
lda #$11
ldy #$4
sta (sp),y
; crc, 0
lda #$00
jsr _SD_command ; rely on command to teardown stack
jsr _SD_readRes1
cmp #$ff ; if 0xFF then you failed
beq end
sta tmp3 ; tmp3 = read
; y = read_attempts
ldy #$0
resp_loop:
lda #$ff
jsr _spi_exchange
sta tmp2 ; tmp2 = read
lda tmp2
cmp #$ff
bne got_resp
iny
bne resp_loop
bra after_read
got_resp:
ldx #$2
ldy #$00
load_loop:
lda #$ff
jsr _spi_exchange
sta (ptr1)
inc ptr1
bne @2
inc ptr1 + 1
@2: dey
bne load_loop
ldy #$00
dex
bne load_loop
lda #$ff
jsr _spi_exchange
lda #$ff
jsr _spi_exchange
after_read:
lda tmp2
sta (ptr2)
lda tmp3
end:
pha
lda #$ff
jsr _spi_exchange
lda #$00 ; this gets ignored anyway
jsr _spi_deselect
lda #$ff
jsr _spi_exchange
pla
rts
.endproc