Switch to use DMA and clean up boot code

boot/boot.68k

@@ -22,21 +22,20 @@ phead_loop:
 move.l (a0), d1 | If the type of the program header isn't 1 (LOAD), skip the header
 cmpi.l #0x1, d1
 bne.b next_seg
-| Zero the destination memory of the program header
-move.l (20, a0), d1 | Put the memory size of the program header - 1 in d1
+| Zero the destination memory
+move.l (20, a0), d1 | Put the memory size - 1 in d1
 subq.l #0x1, d1
-move.l (8, a0), a1 | Put the starting memory address of the program header in a1
+move.l (8, a0), a1 | Put the starting memory address in a1
 zero_loop:
 move.b #0, (a1)+ | Zero a byte of the destination memory
 dbra d1, zero_loop | Loop back if there is more to zero
-| Copy the data of the program header from the loaded file into position
-move.l (16, a0), d1 | Put the file size of the program header - 1 in d1
+| Copy the data from the loaded file into position
+move.l (16, a0), d1 | Put the file size - 1 in d1
+beq.b next_seg | If the file size is 0, skip the copy (ex, .bss section)
 subq.l #0x1, d1
-cmpi.l #0xFFFFFFFF, d1 | If the file size is 0, skip the copy (ex, .bss section)
-beq.b next_seg
-move.l (4, a0), a1 | Put the address of the start of the loaded program header's data in a1
+move.l (4, a0), a1 | Put the address of the loaded data in a1
 adda.l #0xA000, a1
-move.l (8, a0), a2 | Put the starting memory address of the program header in a2
+move.l (8, a0), a2 | Put the starting memory address in a2
 load_loop:
 move.b (a1)+, (a2)+ | Copy a byte of data into position
 dbra d1, load_loop | Loop back if there is more to copy
@@ -68,22 +67,11 @@ ffc_done:
 | Destination in a1
 | Start sector in d0.l
 | Sector count in d1.l
-| Clobbers a1, d1
 read_sectors:
 move.l d0, (a0) | Set the sector number
 move.l d1, (4, a0) | Set the sector count
-move.w #0x0, (8, a0) | Issue a read command
-| Transfer 0x200 (512) * sector_count bytes from the storage card's data register to (a1)
-lsl.l #8, d1 | d0 = d0 * 256 to compute the number of words to transfer
-subq.l #0x1, d1 | Subtract 1 from the word count to account for the extra loop done by dbra
-bra.b rs_loop
-rs_loop_swap:
-swap.w d1
-rs_loop:
-move.w (0xA, a0), (a1)+ | Transfer a word of sector data to the destination
-dbra.w d1, rs_loop 
-swap.w d1
-dbra.w d1, rs_loop_swap
+move.l a1, (0xC, a0) | Set the destination address
+move.w #0x1, (8, a0) | Issue a DMA read command
 rts
 
 .if . != 512