include elf.i
  include term.i
  include traps.i
  include vmem.i
  include pmem.i
  include initrd.i
  include tasking.i
  include start.i
  include memory.i
  section .text,text
  public main
main:
  move.l #inital_stack, a7 ; Load the initial stack pointer
  jsr term_init
  jsr traps_init
  jsr vmem_init
  jsr pmem_init
  jsr initrd_init
  jsr pmem_pop_frame
  move.l #0, d2
  move.l #$FEF000, a0
  move.l #1, d1
  move.l #$2, d3
  move.l d0, -(a7)
  jsr vmem_map_to
  move.l (a7)+, d0
  move.l #($FEF000+$1000), a7
  clrfo
main.elf_header: fo.b Elf32_Ehdr.sizeof
  link a6, #__FO ; Create a stack frame
  move.l d0, a0
  jsr tasking_init
  ; Activate the address space for init
  move.l #init_addr_space, a0
  jsr vmem_activate_addr_space
  ; Get the offset of init in the initrd
  move.l #init_name, a0
  jsr initrd_find_file
  move.l d0, d5
  ; Read the ELF header
  lea.l (main.elf_header,a6), a0
  move.l #0, d1
  move.l #Elf32_Ehdr.sizeof, d2
  jsr initrd_read_bytes
  ; Allocate elf_header.e_phnum * 32 bytes to read the program headers into
  clr.l d0
  move.w (main.elf_header+Elf32_Ehdr.e_phnum,a6), d0
  move.l d0, d4
  lsl.l #5, d0
  move.l d0, d2
  jsr malloc
  ; Read the program headers
  move.l (main.elf_header+Elf32_Ehdr.e_phoff,a6), d1
  move.l a0, -(a7)
  move.l d5, d0
  jsr initrd_read_bytes
  move.l (a7)+, a2
  ; Loop through the program headers
  subi.l #1, d4
phead_loop:
  ; If the program header's type is not LOAD, skip it
  move.l (Elf32_Phdr.p_type,a2), d0
  cmpi.l #PT_LOAD, d0
  bne.w skip_pheader
  ; Get the memory size of the pheader into d0 and round it to the next multiple of 4096 
  ; round_size = p_memsz & 0xFFF > 0 ? p_memsz & ~(0xFFF) + 1 : p_memsz & ~(0xFF)
  move.l (Elf32_Phdr.p_memsz,a2), d0
  andi.l #$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 (Elf32_Phdr.p_vaddr,a2), a0
  move.l #0, d1
  move.l #6, d2
  jsr vmem_map
  ; Zero the segment's memory
  move.l (Elf32_Phdr.p_vaddr,a2), a0
  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 (Elf32_Phdr.p_vaddr,a2), 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 abobe
  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 (Elf32_Phdr.p_vaddr,a2), 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 vmem_set_flags
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 #init_addr_space, a0
  move.l (main.elf_header+Elf32_Ehdr.e_entry,a6), a1
  jsr tasking_new_process
  unlk a6 ; Tear down the stack frame
  jsr tasking_exit

  section .bss,bss
  ds.b 4096
inital_stack:

  section .data,data
init_name: dc.b "init",0
  align 1
init_addr_space: dc.l $0, $0, $0, kernel_map - $6000