eb72e83629
Looks like cprintf modifies ptr3, so make sure to save it if you are calling that. There also may have been an issue with how the previous sector address was calculated, the one which does not account for carries seems to work.
161 lines
3.7 KiB
ArmAsm
161 lines
3.7 KiB
ArmAsm
.importzp sp, ptr1, ptr2, ptr3, ptr4, tmp1, tmp2, tmp3, sreg, data_start
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.autoimport on
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.export fatbuf
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.feature string_escapes
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.MACPACK generic
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fatbuf = $A000
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filebuf = $B000
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.segment "BOOTLOADER"
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sectors_per_cluster = $800D
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reserved_sectors = $800E
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fat_count = $8010
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sectors_per_fat = $8024
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_start:
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lda #<str
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ldx #>str
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jsr _cputs
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; Read root directory entry into fatbuf
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lda data_start
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ldx data_start + 1
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jsr pushax
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stz sreg
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stz sreg+1
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jsr pusheax
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lda #<fatbuf
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ldx #>fatbuf
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jsr pushax
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lda #<ptr1
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ldx #>ptr1
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jsr _SD_readSingleBlock
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lda #<fatbuf
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ldx #>fatbuf
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jsr _SD_printBuf
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lda #$20 ; Start at first directory entry (first is a disk label)
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sta ptr3
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lda #>fatbuf
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sta ptr3 + 1
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ldy #$0b ; look for attributes
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@1: lda (ptr3),y
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cmp #$0f ; if attribute is 0xf, this is a lfn
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bne @2 ; if not an lfn, then try to read filename
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@next: clc ; otherwise, go to the next entry (+0x20)
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lda ptr3
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adc #$20
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sta ptr3
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bcc @4
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inc ptr3 + 1
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@4: lda #<word_str
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ldx #>word_str
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jsr pushax
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lda ptr3
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ldx ptr3 + 1
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pha
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phx
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jsr pushax
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phy
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ldy #$4
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jsr _cprintf
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ply
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plx
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stx ptr3 + 1
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pla
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sta ptr3
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bra @1
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@2: ldy #11 ; ignore the attributes. Write null to make a string
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lda #$00
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sta (ptr3),y
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lda ptr3 ; store address of the filename string on the stack
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pha
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ldx ptr3 + 1
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phx
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jsr _cputs ; print out short filenames as we read them
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lda #$0d
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jsr _cputc
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lda #$0a
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jsr _cputc
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lda #<kernel_str ; load the string "KERNEL O65"
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ldx #>kernel_str
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jsr pushax
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plx ; then push the string we read earlier
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pla
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jsr _strcmp
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bne @next ; if they are not equal then try next entry
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lda #<_good ; print match if we found it
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ldx #>_good
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jsr _cputs ; otherwise continue on
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lda #<word_str
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ldx #>word_str
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jsr pushax
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lda ptr3
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pha
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lda ptr3 + 1
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pha
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ldy #$1d ; load file size (256)
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lda (ptr3),y
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lsr ; divide by 2 to get file size (512)
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jsr pusha0
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ldy #$4
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jsr _cprintf
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pla
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sta ptr3 + 1
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pla
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sta ptr3
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ldy #$1b ; load high byte of low first cluster
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lda (ptr3),y
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tax
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dey
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lda (ptr3),y ; load low byte of low first cluster
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sec
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sbc #$02 ; don't handle carry, assume low byte is not 0 or 1
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ldx data_start + 1 ; load x as high data start
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asl ; multiply cluster num (minus 2) by 8
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asl
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asl
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clc
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adc data_start ; add that to low data start
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bcc @5 ; handle carry
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inx
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@5: stz sreg
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stz sreg+1
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phx
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pha
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jsr pusheax
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lda #<filebuf
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ldx #>filebuf
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jsr pushax
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lda #<ptr1
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ldx #>ptr1
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jsr _SD_readSingleBlock
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lda #<filebuf
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ldx #>filebuf
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jsr _SD_printBuf
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@end: bra @end
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str: .asciiz "boot2\r\n"
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kernel_str: .asciiz "KERNEL O65"
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_good: .asciiz "Found KERNEL\r\n"
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word_str: .asciiz "Word Value: %x\r\n" |