### GNU Mes --- Maxwell Equations of Software
### Copyright (C) 2016 Jeremiah Orians
### Copyright © 2022 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
###
### This file is part of GNU Mes.
###
### GNU Mes is free software; you can redistribute it and/or modify it
### under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 3 of the License, or (at
### your option) any later version.
###
### GNU Mes is distributed in the hope that it will be useful, but
### WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
### GNU General Public License for more details.
###
### You should have received a copy of the GNU General Public License
### along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.

:_start
	; sp has to be 16 byte aligned but we only want to deal with 8 byte registers,
	; so use a normal register as sp
	INIT_SP		; mov x18, sp
	LDR_X0_[SP]
	ADD_X1_SP_8

	; M2-Planet also has a frame pointer, x17
	SET_BP_FROM_SP	; mov x17, x18

	; Separate out envp, get our args for main
	PUSH_X0		; argc
	PUSH_X1		; argv (yes, that's above the top of the stack)
	SET_X1_TO_2	; One word for argc, one word for a null pointer
	ADD_X0_X1_X0
	SET_X1_TO_8
	MUL_X0_X1_X0
	ADD_X0_BP_X0
	PUSH_X0		; envp

	; Store envp to environ global
	LOAD_W1_AHEAD
	SKIP_32_DATA
	&GLOBAL_environ
	STR_X0_[X1]

	; Set stdin, stdout, and stderr
	SET_X0_TO_0
	LOAD_W1_AHEAD
	SKIP_32_DATA
	&GLOBAL___stdin
	STR_X0_[X1]

	SET_X0_TO_1
	LOAD_W1_AHEAD
	SKIP_32_DATA
	&GLOBAL___stdout
	STR_X0_[X1]

	SET_X0_TO_2
	SKIP_32_DATA
	&GLOBAL___stderr
	STR_X0_[X1]

	; Call our main function
	LOAD_W16_AHEAD
	SKIP_32_DATA
	&FUNCTION_main
	BLR_X16

	; Exit
	; Return from main is already in x0
	SET_X8_TO_SYS_EXIT
	SYSCALL