Start work on RAM card sort

rom.68k

@@ -6,6 +6,8 @@ _start:
 romfindret:
   move.l a0, a6 | Save the ROM card IO base in a6 for later
   lea (0xF0, a6), a7 | Set up the stack at the end of the ROM's IO space RAM
+  move.l #0x8000, a1
+  bsr.w find_all_ram_cards
   bsr.b find_largest_ram | Find the largest RAM card and put the IO base in a5
   move.l a0, a5
   move.l d0, d7
@@ -76,3 +78,41 @@ flr_done:
   rts
 fakestack: 
   .long romfindret
+
+| 1KB buffer in a1
+| Returns list length in d0
+find_all_ram_cards:
+  move.b #0, d0 | d0 holds the number of RAM cards found.
+  move.l #0xff0000, a0 | a0 holds the address of the current card.
+farc_loop:
+  lea (0x100, a0), a0 | adda.l #$100,a0 ; Move to the next card
+  move.w (0xfe, a0), d1 | Load the type of the card into d1
+  beq.b farc_done | If the type is 0 (empty slot), we have scanned all cards, so exit the loop
+  cmp.w #0x2, d1 | If the card isn't a RAM card, skip it
+  bne.b farc_loop 
+  move.l a0, (a1)+ | Write the IO base address into the buffer and advance the buffer pointer
+  addq.b #1, d0 | Increment the count of found RAM cards
+  bra.b farc_loop | Loop back and check the next card
+farc_done:
+  rts
+
+| Buffer in a0
+| Length in d0
+| optimized bubble sort to sort RAM cards by size
+sort_ram_cards:
+move.b #0, d1 | d1 = newlen
+move.b #1, d2 | d2 = i
+src_inner_loop:
+| todo compare sizes
+| PSEUDO: cmp snd, fst
+ble.b src_pair_sorted
+| todo swap values
+move.b d2, d1 | i = newlem
+src_pair_sorted:
+addq.b #1, d2 | i++
+cmp.b d0, d2 | if i < length,  branch to inner loop
+blt.b src_inner_loop 
+move.b d1, d0 | len = newlen
+cmp #1, d0 | if n > 1, branch to outer loop
+bgt.b sort_ram_cards
+rts