# uskel runtime and start; include this at the top.

.section .init
.global _start
_start:
	jmp _uskel_start

.include "include/macros.s"

.section .bss
_memory_state:
	cell 0 # bottom of allocation (grows down)
	cell 0 # region start
	cell 0 # region end
	cell 0 # program entry rsp (aka the actual stack)

.section .text

_uskel_alloc_basic_mem:
	mov $0x100000, %r15 # desired size

	mov $0x9, %rax # mmap
	mov $0, %rdi # addr = NULL
	mov %r15, %rsi # len = %rcx
	mov $0x3, %rdx # prot = PROT_READ 0x1 | PROT_WRITE 0x2
	mov $0x22, %r10 # flags = MAP_PRIVATE 0x2 | MAP_ANONYMOUS 0x20
	mov $-1, %r8 # fd = -1
	mov $0, %r9 # off = 0
	syscall
	mov $_memory_state, %rdi
	mov %rax, 010(%rdi)
	add %r15, %rax
	mov %rax, (%rdi)
	mov %rax, 020(%rdi)
	retq

_uskel_start:
	call _uskel_alloc_basic_mem
	# use the stack pointer for easy writing to the heap,
	# but back it up to memory state
	mov $_memory_state, %rdi
	mov %rsp, 030(%rdi)
	mov 0(%rdi), %rsp

	# push a thunk for main
	pushq $0
	pushq $main

	mov $0, %rsi # set continuation to exit
	enter %rsp # run the program
	# Q: are there gonna be functions that have both the argument AND the cont?
	# A: No, stuff is either entered as return-continuation (takes res, cont has to be saved) or as forward call (takes cont)
	# (needs validation)