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Change startup code to use kernel's find_first_card

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This commit is contained in:
pjht 2023-03-24 19:39:09 -05:00
parent 883cf37e85
commit d8565dcd78
Signed by: pjht
GPG Key ID: 7B5F6AFBEC7EE78E
2 changed files with 2 additions and 18 deletions
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1
kernel/cards.68k
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@ -2,6 +2,7 @@
| Finds the first card with the type in d0.b, and returns it's IO base address in a0, or 0 if not found
| Clobbers d1
| Warning to developers: This function must only use PC-relative addressing as it is called from early boot before the kernel is properly mapped.
find_first_card:
move.l #0xff0000, a0 | a0 holds the address of the current card
ffc_loop:

19
kernel/start.68k
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@ -5,7 +5,7 @@ _start:
move.l d0, d2 | Move the number of program headers to d2
move.l a0, a1 | Move the program headaer pointer to a1
move.b #0x5, d0 | Get the pointer to the MMU card
bsr.w find_first_card_early
jsr (find_first_card - 0xC00000)
cmpa.l #0, a0 | Abort if there is no MMU card
beq.w no_mmu
subq.w #0x1, d2 | Adjust the number of program headers for dbra
@ -59,23 +59,6 @@ jmp (higher_bridge - 0xC00000) | Jump to the lower-half equivalent of the bridgi
no_mmu:
stop #2700 | If there was no MMU card, halt the CPU
| Finds the first card with the type in d0.b, and returns it's IO base address in a0, or 0 if not found
| Clobbers d1
find_first_card_early:
move.l #0xff0000, a0 | a0 holds the address of the current card
ffc_early_loop:
lea (0x100, a0), a0 | Move to the next card
move.b (0xff, a0), d1 | Load the type of the card into d1
beq.b ffc_early_notfound | If the type is 0 (empty slot), we have scanned all cards, so exit the loop
cmp.b d0, d1 | If the card is the type we want, return with the address in a0
beq.b ffc_early_done
bra.b ffc_early_loop | Loop back and check the next card
ffc_early_notfound:
move.l #0x0, a0
ffc_early_done:
rts
.text
higher_bridge:
move.w #1, (0x14, a0) | Enable the MMU