127 lines
1.6 KiB
Z80 Assembly
127 lines
1.6 KiB
Z80 Assembly
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strcmp:
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strcmp_loop:
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ld a, (ix+0)
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ld b, (iy+0)
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cp b
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jp nz, strcmp_different
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cp 0
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ret z
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inc ix
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inc iy
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jp strcmp_loop
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strcmp_different:
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ld a, 1
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ret
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.global read_init
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; Reads init.elf off the disk to 0x8000 in memory
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read_init:
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ld c, 0
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ld de, 1
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ri_find_loop:
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ld hl, 0x8000
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push bc
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call read_sector
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ld ix, 0x8001
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ld iy, init_str
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call strcmp
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pop bc
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jp z, ri_init_found
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push bc
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ld b, 0
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ld a, (0x8000)
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ld c, a
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ld hl, 0x8004
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add hl, bc
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ld c, (hl)
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inc hl
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ld b, (hl)
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ld l, c
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ld h, b
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inc hl
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add hl, de
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ld e, l
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ld d, h
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pop bc
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ld a, c
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adc a, 0
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ld c, a
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jp ri_find_loop
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ri_init_found:
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push bc
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ld b, 0
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ld a, (0x8000)
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ld c, a
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ld hl, 0x8004
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add hl, bc
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pop bc
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ld b, (hl)
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ld hl, 1
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add hl, de
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ld e, l
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ld d, h
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ld a, c
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adc a, 0
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ld c, a
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ld hl, 0x8000
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ri_read_loop:
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push bc
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call read_sector
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pop bc
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push hl
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ld hl, 1
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add hl, de
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ld e, l
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ld d, h
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ld a, c
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adc a, 0
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ld c, a
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pop hl
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djnz ri_read_loop
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ret
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; Given a sector number in C:DE and a buffer address in HL, reads the sector off disk.
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read_sector:
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push bc
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ld c,0xFF ; Force the top half of the IO address to be the id of the card,
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ld a, (disk_num) ; so the block transfer instructions can be used
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out (c), a
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pop bc
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ld a, c
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ld c, 0
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out (c), e
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inc c
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out (c), d
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inc c
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out (c), a
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ld b, 0x0 ; Setup a transfer of 256 bytes (1 sector) at a time
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ld c, 0x3 ; from the storage device's data port
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inir
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ld c,0xFF ; Unforce the top half of the IO address
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in a,(c)
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ret
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.global find_disk
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; Clobbers A and HL
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find_disk:
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ld b,0x4
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call find_first_card
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ld a, l
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ld (disk_num), a
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ret
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disk_num: .ds.b 1
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/* initrd: */
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/* .incbin "initrd" */
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/* initrd_end: */
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init_str: .asciz "init.elf"
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