318 lines
4.5 KiB
Z80 Assembly
318 lines
4.5 KiB
Z80 Assembly
.global _start
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_start:
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call get_free_frame
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ld b, c
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ld e, l
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ld d, h
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ld c, 0x9
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call set_frame
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call get_free_frame
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ld a, c
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ld (send_page_addr), a
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ld (send_page_addr+1), hl
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ld b, c
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ld e, l
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ld d, h
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ld c, 0x8
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call set_frame
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ld hl, 0x9000
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ld de, 0x9001
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ld bc, 0x1000
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ld (hl), 0x0
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ldir
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call get_free_mailbox
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push hl
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ld de, 2
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call proc_map_set
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pop hl
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ld (vfs_mailbox_num), hl
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call get_free_mailbox
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ld (fs_mailbox_num), hl
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msg_loop:
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call yield
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yield_back:
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ld hl, (vfs_mailbox_num)
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call mb_read
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mb_read_done:
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ld a, b
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cp 1
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jp z, msg_loop
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msg_read:
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push bc
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push de
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push hl
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ld b, c
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ld c, 0xB
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call set_frame
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set_frame_done:
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ld hl, (0xB000) ; Load destination mailbox into HL and save it on the stack
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push hl
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ld hl, 0xB002
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; Handling code goes here
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ld a, (hl)
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inc hl
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cp 0x0
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jp z, register_fs
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cp 0x1
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jp z, mount
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cp 0x2
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jp z, open
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operation_done:
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pop hl
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pop ix
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pop de
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pop bc
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call mb_send
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jp msg_loop
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register_fs:
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ld a, (fs_count)
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ld l, a
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ld h, 0x0
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add hl, hl
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add hl, hl
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add hl, hl
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add hl, hl
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ld de, data_fs_offset
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add hl, de
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ld de, 0x9000
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add hl, de
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push hl
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pop de
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ld hl, 0xB003
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ld bc, 16
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ldir
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ld a, (fs_count)
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inc a
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ld (fs_count), a
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jp operation_done
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; String pointer 1 in IX, 2 in IY
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; Return in A
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strcmp:
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strcmp_loop:
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ld a, (iy)
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ld b, a
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ld a, (ix)
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cp b
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jp nz, strcmp_loopend
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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_loopend:
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ld a, (iy)
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ld b, a
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ld a, (ix)
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sub b
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ret
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mount:
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ld a, (mount_count)
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ld l, 0x0
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ld h, a
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ld de, 0x9000 + data_mount_offset
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add hl, de
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push hl
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pop de
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push de
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ld hl, 0xB003
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ld bc, 0xFC
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ldir
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; FS type at 0xB1FF
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ld a, (fs_count)
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ld b, a
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ld hl, data_fs_offset + 0x9000
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ld de, 0x10
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mount_loop1:
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push hl
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pop ix
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ld iy, 0xB1FF
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push bc
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call strcmp
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pop bc
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cp 0
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jp mount_loop1_done
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add hl, de
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djnz mount_loop1
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mount_loop1_done:
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; hl -> pointer to fs type info
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; top of stack -> pointer to open mount info slot
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ld de, 14
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add hl, de
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pop ix
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; hl -> pointer to byte 15 of fs type info
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; ix -> pointer to open mount info slot
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ld de, 0xFD
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add ix, de
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; ix -> pointer to offset 0xFD of mount info
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; fs info word starting at 0xE -> mount info word starting at 0xFD
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ld e, (hl)
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inc hl
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ld d, (hl)
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ld (ix), e
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ld (ix+1), d
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ld hl, (fs_mailbox_num)
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ld (0x8000), hl
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ld a, 0x2
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ld (0x8002), a
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push ix
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push de
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ld hl, 0xB0FF
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ld de, 0x8003
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ld bc, 256
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ldir
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ld a, (send_page_addr)
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ld c, a
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ld de, (send_page_addr+1)
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ld ix, 0x0
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pop hl
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call mb_send
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mount_wait_loop:
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call yield
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ld hl, (fs_mailbox_num)
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call mb_read ; Read a message
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ld a, b ; Loop if there is no message
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cp 0
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jp nz, mount_wait_loop
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pop ix
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; response byte 1 -> mount info byte at offset 0xFF
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ld a, (0x8000)
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ld (ix+2), a
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ld a, (mount_count)
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inc a
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ld (mount_count), a
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jp operation_done
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; String pointer 1 in IX, 2 in IY
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; Return in A
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vfsstrcmp:
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vfsstrcmp_loop:
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ld a, (iy)
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ld b, a
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ld a, (ix)
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cp b
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jp nz, vfsstrcmp_loopend
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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 vfsstrcmp_loop
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vfsstrcmp_loopend:
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ld a, (ix)
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cp 0
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ret z
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ld a, (iy)
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ld b, a
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ld a, (ix)
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sub b
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ret
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open:
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; Scan mountpoints for largest prefix matching path
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ld hl, data_mount_offset + 0x9000
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ld bc, 0
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ld de, 0
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open_mount_scan:
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ld a, (hl)
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cp 0
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jp z, open_mount_scan_done
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push hl
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pop ix
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ld iy, 0xB003
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push bc
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call vfsstrcmp
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pop bc
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cp 0
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jp nz, open_no_prefix
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push hl
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pop de
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call strlen
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open_no_prefix:
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ld a, h
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inc a
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ld h, a
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ld l, 0
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jp open_mount_scan
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open_mount_scan_done:
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; Send open request to FS w/ path-prefix and mount ID
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ld hl, 0xB003
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add hl, bc
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push de
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; mountpoint path -> 0x8003-0x8103 (exclusive end)
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ld de, 0x8003
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ld bc, 0x100
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ldir
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pop de
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; mount info byte 0xFF -> 0x8103
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ld e, 0xFF
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ld a, (de)
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ld (0x8103), a
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; imm 0x0 -> 0x8002
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ld a, 0x0
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ld (0x8002), a
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; fs_mailbox_num (16bit) -> 0x8000,0x8001
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ld hl, 0x8000
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ld bc, (fs_mailbox_num)
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ld (hl), c
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inc hl
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ld (hl), b
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; mount info word 0xFD -> hl
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ld e, 0xFD
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ld a, (de)
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ld l, a
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inc de
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ld a, (de)
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ld h, a
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push hl
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ld a, (send_page_addr)
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ld c, a
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ld de, (send_page_addr+1)
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ld ix, 0x0
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call mb_send
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open_wait_loop:
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call yield
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ld hl, (fs_mailbox_num)
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call mb_read ; Read a message
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ld a, b ; Loop if there is no message
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cp 0
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jp nz, open_wait_loop
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pop hl
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ld a, (0x8002)
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cp 0
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jp nz, mb_override
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ld a, (0x8003)
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cp 0
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jp nz, mb_override
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jp no_mb_override
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mb_override:
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ld hl, (0x8002)
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no_mb_override:
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ld (0xB002), hl
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; word at 0x8000 -> 0xB000
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ld a, (0x8000)
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ld (0xB000), a
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ld a, (0x8001)
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ld (0xB001), a
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jp operation_done
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vfs_mailbox_num: .ds.b 2
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fs_mailbox_num: .ds.b 2
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send_page_addr: .ds.b 3
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fs_count: .ds.b 1
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mount_count: .ds.b 1
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.equ data_fs_offset, 0x0
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.equ data_mount_offset, 0x200
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.equ fs_name_offset, 0x0
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.equ fs_pid_offset, 0xE
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.equ mount_path_offset, 0x0
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.equ mount_fs_pid_offset, 0xFD
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.equ mount_fs_id_offset, 0xFF
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