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Load a multi-sector file and execute it

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This commit is contained in:
Byron Lathi
2023-08-14 20:44:27 -07:00
parent 3bd022107e
commit a657957ae2
2 changed files with 67 additions and 15 deletions
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68
sw/bios/bootloader.s
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@@ -90,26 +90,70 @@ _main:
jsr _cputs
lda #<_cluster
ldx #>_cluster
jsr pushax
ldy #$15
lda (ptr3),y
tax
dey
lda (ptr3),y
jsr pushax
ldy #$1b
lda (ptr3),y
tax
dey
lda (ptr3),y
sec
sbc #$02 ; don't handle carry, assume <256
; now a is the cluster num minus 2. We need to multiply this by
; 8 and add it to 0x77f0
; multiply by 8 is asl3
ldx #$77
asl
asl
asl
clc
adc #$f0
bcc @3
inx
@3: pha
phx
lda #$00
sta sreg
lda #$00
sta sreg+1
plx
pla
phx
pha
jsr pusheax
lda #<buf
ldx #>buf
jsr pushax
ldy #$6
jsr _cprintf
lda #<ptr1
ldx #>ptr1
jsr _SD_readSingleBlock
lda #$00
sta sreg
lda #$00
sta sreg+1
pla
plx
inc
jsr pusheax
lda #<buf
ldx #>buf
inx
inx
jsr pushax
lda #<ptr1
ldx #>ptr1
jsr _SD_readSingleBlock
jmp buf
bra @end
; Now we have the cluster number of the bootloader
; Now we have the cluster number of the bootloader (3)
; this means we need to read from address 00ef_e000 + ((3 -2) * 8 * 512)
; 00eff000 is the address we want, which is efe000 + 4096
@fail: lda #<_fail