fibs work

1 files changed, 54 insertions, 0 deletions

diff --git a/include/uskel.s b/include/uskel.s
new file mode 100644
index 0000000..136b382
--- /dev/null
+++ b/include/uskel.s
@@ -0,0 +1,54 @@
+
+# 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)