40 lines
1.6 KiB
Plaintext
40 lines
1.6 KiB
Plaintext
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section .text,text
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; Finds the first card with the type in d0.b, and returns it's IO base address in a0, or 0 if not found
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; Clobbers d1
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; Warning to developers: This function must only use PC-relative addressing as it is called from early boot before the kernel is properly mapped.
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public find_first_card
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find_first_card:
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move.l #$ff0000, a0 ; a0 holds the address of the current card
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ffc_loop:
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lea ($100,a0), a0 ; Move to the next card
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move.w ($fe,a0), d1 ; Load the type of the card into d1
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beq.b ffc_done ; If the type is 0 (empty slot), we have scanned all cards, so exit the loop
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cmp.b d0, d1 ; If the card is the type we want, return with the address in a0
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beq.b ffc_done
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bra.b ffc_loop ; Loop back and check the next card
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ffc_done:
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rts
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get_all_cards:
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; Gets the indexes of the cards with the specified type
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; a0 is a pointer to the buffer to store the results in
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; d0 is the length of the buffer in 4 byte units
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; d1 is the type of card to find
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move.l #$ff0000, a1 ; a0 holds the address of the current card
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gac_loop:
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lea ($100,a1), a1 ; Move to the next card
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move.w ($fe,a1), d2 ; Load the type of the card into d1
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cmp.b d1, d2 ; Check whether the type of the current card is the type we want
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bne.b gac_next ; Skip the card if it is not
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move.l a1, (a0) ; Put the card base into the buffer
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lea ($4,a0), a0 ; Move to the next buffer location
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subq.w #1, d0 ; Decement the count of available buffer locations
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gac_next:
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cmpa.l #$ffff00, a1 ; Check if we have gone through all the cards
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beq.b gac_done ; If so, return
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cmpi.b #0, d0 ; Check if we have filled the buffer
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beq.b gac_done ; If so, returm
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bra.b gac_loop
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gac_done:
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rts
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