init/main.68k

  include cards.i
  include initrd.i
  include syscalls.i
  include elf.i
  include memory.i
  section .text,text
  public main
main:
  clrfo
main.elf_header: fo.b Elf32_Ehdr.sizeof
  link a6, #__FO ; Create a stack frame
  move.l #msg, a0
  jsr syscall_println
  jsr cards_init
  jsr initrd_init
  move.l #test_proc_name, a0
  jsr initrd_find_file
  move.l d0, d5
  ; Read the ELF header
  lea.l (main.elf_header,a6), a0
  move.l #0, d1
  move.l #Elf32_Ehdr.sizeof, d2
hdr_read:
  jsr initrd_read_bytes
  ; Allocate elf_header.e_phnum * 32 bytes to read the program headers into
  clr.l d0
  move.w (main.elf_header+Elf32_Ehdr.e_phnum,a6), d0
  move.l d0, d4
  lsl.l #5, d0
  move.l d0, d2
  jsr malloc
phdr_read:
  ; Read the program headers
  move.l (main.elf_header+Elf32_Ehdr.e_phoff,a6), d1
  move.l a0, -(a7)
  move.l d5, d0
  jsr initrd_read_bytes
  move.l (a7)+, a2
phead_loop:
  ; If the program header's type is not LOAD, skip it
  move.l (Elf32_Phdr.p_type,a2), d0
  cmpi.l #PT_LOAD, d0
  bne.w skip_pheader
  ; Get the memory size of the pheader into d0 and round it to the next multiple of 4096
  ; round_size = p_memsz & 0xFFF > 0 ? p_memsz & ~(0xFFF) + 1 : p_memsz & ~(0xFF)
  move.l (Elf32_Phdr.p_memsz,a2), d0
  andi.l #$FFF, d0
  beq.b .1
  move.l #$1000, d1
  bra.b .2
.1:
  move.l #0, d1
.2:
  move.l (Elf32_Phdr.p_memsz,a2), d0
  andi.l #(~$FFF), d0
  add.l d1, d0
  ; Shift the rounded size right by 12 to get the number of pages the pheader takes up
  lsr.l #8, d0
  lsr.l #4, d0
  ; Map the segment to free memory
  move.l #6, d1
  jsr syscall_vmem_map_free
  move.l a0, a3 ; Save the allocated address in a3
  ; Offset the allocated address by the page offset in the pheader's virtaddr field
  move.l (Elf32_Phdr.p_vaddr,a2), d0
  andi.l #$FFF, d0
  adda.l d0, a3
  move.l a3, a0
  ; Zero the segment's memory
  move.l (Elf32_Phdr.p_memsz,a2), d0
  subi.l #1, d0
.3:
  move.b #0, (a0)+
  dbra d0, .3
  ; Read the segment's data off disk
  move.l d5, d0
  move.l (Elf32_Phdr.p_offset,a2), d1
  move.l (Elf32_Phdr.p_filesz,a2), d2
  move.l a3, a0
  jsr initrd_read_bytes
  ; Get the memory size of the pheader into d0 and round it to the next multiple of 4096 
  ; Same as above
  move.l (Elf32_Phdr.p_memsz,a2), d0
  andi.l #$FFF, d0
  beq.b .4
  move.l #$1000, d1
  bra.b .5
.4:
  move.l #0, d1
.5:
  move.l (Elf32_Phdr.p_memsz,a2), d0
  andi.l #(~$FFF), d0
  add.l d1, d0
  ; Shift the rounded size right by 12 to get the number of pages the pheader takes up
  lsr.l #8, d0
  lsr.l #4, d0
  ; Get the pheader's flags and make them into the page mapping flags, put the
  ; argumemts into the right registers, and set the flags for the pheader's memory
  move.l d0, d1
  move.l a3, a0
  move.l (Elf32_Phdr.p_flags,a2), d0
  andi.l #PF_W, d0
  move.l (Elf32_Phdr.p_flags,a2), d2
  andi.l #PF_X, d2
  lsl.l #3, d2
  or.l d2, d0
  ori.l #$4, d0
  move.l #$0, d2
  jsr syscall_vmem_set_flags
  move.l a3, a0
  ; Get the memory size of the pheader into d0 and round it to the next multiple of 4096
  ; Same as above
  move.l (Elf32_Phdr.p_memsz,a2), d0
  andi.l #$FFF, d0
  beq.b .6
  move.l #$1000, d1
  bra.b .7
.6:
  move.l #0, d1
.7:
  move.l (Elf32_Phdr.p_memsz,a2), d0
  andi.l #(~$FFF), d0
  add.l d1, d0
  ; Shift the rounded size right by 12 to get the number of pages the pheader takes up
  lsr.l #8, d0
  lsr.l #4, d0
; Get the starting page of the allocated memory segment into a0
  move.l a3, d1
  andi.l #(~$FFF), d1
  move.l d1, a0
  move.l (Elf32_Phdr.p_vaddr,a2), a1
dbg:
  jsr syscall_vmem_copy_to_secondary
skip_pheader:
  ; Advance to the next pheader and loop back if there are more
  lea.l (Elf32_Phdr.sizeof,a2), a2
  dbra d4, phead_loop
  ; Create the init process
  move.l (main.elf_header+Elf32_Ehdr.e_entry,a6), a0
  jsr syscall_new_process
  unlk a6
  rts

  section .data,data
msg: dc.b "Hello from init",0
test_proc_name: dc.b "test_proc",0

  section .bss,bss
tmp_stack: ds.b 32
tmp_stack_top: