152 lines
2.4 KiB
Z80 Assembly
152 lines
2.4 KiB
Z80 Assembly
.global _start
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_start:
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ld hl, syscall
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ld a, 0xc3
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ld (0xdffd), a
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ld (0xdffe), hl
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call scan_cards
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call vmem_init
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call pmem_init
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call proc_map_init
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ld c, 0
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call get_frame
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push bc
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ld ix, empty_pagemap
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call pmap_load
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pop bc
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ld c, b
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ld b, 4
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init_page_map_loop:
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ld a, b
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add a, 7
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push bc
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ld b, c
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ld c, a
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ld e, a
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ld d, 0
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call set_frame
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pop bc
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djnz init_page_map_loop
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call tasking_init
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call find_disk
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ld hl, init_str
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call read_init
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ld hl, 0x8000
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after_file_pos:
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push hl
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pop iy
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ld l, (iy+0x1C) ; Load IX with the start of the program headers in memory
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ld h, (iy+0x1D) ; Load IX with the start of the program headers in memory
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push hl
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pop ix
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push iy
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pop bc
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add ix, bc
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ld a, (iy+0x2C) ; load B with the number of program headers
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ld b, a
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phead_loop:
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ld a, (ix+0)
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cp 1
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jp NZ, next_seg
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push bc
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ld c, (ix+20)
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ld b, (ix+21)
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; b = if c > 0 || b & 0xF > 0 {
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; (b & 0xF0) + 0x10
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; } else {
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; b & 0xF0
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; } >> 4
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ld a, c
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cp 0
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jp z, cmp2
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jp blk1
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cmp2:
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ld a, b
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and 0xF
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cp 0
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jp z, blk2
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blk1:
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ld a, b
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and 0xF0
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add a, 0x10
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ld b, a
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jp end1
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blk2:
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ld a, b
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and 0xF0
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ld b, a
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end1:
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srl b
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srl b
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srl b
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srl b
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ld c, (ix+9)
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srl c
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srl c
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srl c
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srl c
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push iy
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push ix
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push de
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page_alloc_loop:
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push bc
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call get_free_frame
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ld b, c
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ld d, h
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ld e, l
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pop hl
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ld c, l
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push hl
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call set_frame
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pop bc
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inc c
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djnz page_alloc_loop
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pop de
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pop ix
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pop iy
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;Zero out the segments place in memory
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ld c, (ix+20) ; Load the byte counter with the number of bytes to zero out
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ld b, (ix+21)
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ld e, (ix+8) ; Load the destination & source address register with the destination location of the segment in memory
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ld d, (ix+9)
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ld h, d
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ld l, e
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ld (hl), 0 ; Zero out the firts byte in the segment ( Acts as a 'seed' for the zeroing )
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ldir
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ld c, (ix+16) ; Load the byte counter with the number of bytes to transfer
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ld b, (ix+17)
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ld l, (ix+4) ; Load the source address register with the memory address if the segment data
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ld h, (ix+5)
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push iy
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pop de
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add hl, de
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ld e, (ix+8) ; Load the destination address register with the destination location of the segment in memory
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ld d, (ix+9)
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ldir; Do the transfer
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pop bc
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next_seg:
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ld de, 32
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add ix, de
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dec b
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ld a, b
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jp nz, phead_loop
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ld l, (iy+0x18) ; Load HL with the program entry point
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ld h, (iy+0x19) ; Load HL with the program entry point
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ld ix, init_pagemap
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call pmap_set
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ld ix, empty_pagemap
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call pmap_load
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ld iy, init_pagemap
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call new_process
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call yield
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halt
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init_str: .asciz "init.elf"
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empty_pagemap:
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.ds.b 36
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init_pagemap:
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.ds.b 36
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