/* Startup code for Nios II

   Copyright (C) 1995-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   In addition to the permissions in the GNU Lesser General Public

   License, the Free Software Foundation gives you unlimited

   permission to link the compiled version of this file with other

   programs, and to distribute those programs without any restriction

   coming from the use of this file. (The GNU Lesser General Public

   License restrictions do apply in other respects; for example, they

   cover modification of the file, and distribution when not linked

   into another program.)

   Note that people who make modified versions of this file are not

   obligated to grant this special exception for their modified

   versions; it is their choice whether to do so. The GNU Lesser

   General Public License gives permission to release a modified

   version without this exception; this exception also makes it

   possible to release a modified version which carries forward this

   exception.

   The GNU C Library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library.  If not, see

   <http://www.gnu.org/licenses/>.  */

/* This is the canonical entry point, usually the first thing in the text

   segment.

	Note that the code in the .init section has already been run.

	This includes _init and _libc_init

	The stack pointer, sp, will point to the argument count on the stack.

	The initial state of the stack when a userspace process is started is:

	    Purpose			Start Address	Length

	    Unspecified			High Addresses

	    Referenced strings, etc.			Varies

	    Unspecified

	    Null auxilliary vector entry		4bytes

	    Auxilliary vector entries			8bytes each

	    NULL terminator for envp			4bytes

	    Environment pointers	sp+8+4*argc	4bytes each

	    NULL terminator for argv	sp+4+4*argc	4bytes

	    Argument pointers		sp+4		4bytes each

	    Argument count		sp		4bytes

	    Unspecified			Low Addresses

	If the application should register a destructor function with atexit,

	the pointer will be placed in r4. Otherwise r4 will be zero.

	The contents of all other registers are unspecified. User code should

	set fp to zero to mark the end of the frame chain.

	The auxilliary vector is a series of pairs of 32-bit tag and 32-bit

	value, terminated by an AT_NULL tag.

*/

	.text

	.globl _start

	.type _start,%function

_start:

	/* Set up the global pointer.  */

	movhi	gp, %hiadj(_gp)

	addi	gp, gp, %lo(_gp)

	/* Save the stack pointer.  */

	mov	r2, sp

	/* Create room on the stack for the fini, rtld_fini and stack_end args

	   to __libc_start_main. */

	subi	sp, sp, 12

	/* Push stack_end */

	stw	r2, 8(sp)

	/* Push rtld_fini */

	stw	r4, 4(sp)

	/* Set up the GOT pointer.  */

	nextpc	r22

1:	movhi	r2, %hiadj(_gp_got - 1b)

	addi	r2, r2, %lo(_gp_got - 1b)

	add	r22, r22, r2

	/* Push fini */

	movhi	r8, %call_hiadj(__libc_csu_fini)

	addi	r8, r8, %call_lo(__libc_csu_fini)

	add	r8, r8, r22

	ldw	r8, 0(r8)

	stw	r8, 0(sp)

	/* r7 == init */

	movhi	r7, %call_hiadj(__libc_csu_init)

	addi	r7, r7, %call_lo(__libc_csu_init)

	add	r7, r7, r22

	ldw	r7, 0(r7)

	/* r6 == argv */

	addi	r6, sp, 16

	/* r5 == argc */

	ldw	r5, 12(sp)

	/* r4 == main */

	movhi	r4, %call_hiadj(main)

	addi	r4, r4, %call_lo(main)

	add	r4, r4, r22

	ldw	r4, 0(r4)

	/* fp == 0 */

	mov	fp, zero

	/* __libc_start_main (main, argc, argv, init, fini, rtld_fini,

			      stack_end) */

	/* Let the libc call main and exit with its return code.  */

	movhi	r2, %call_hiadj(__libc_start_main)

	addi	r2, r2, %call_lo(__libc_start_main)

	add	r2, r2, r22

	ldw	r2, 0(r2)

	callr	r2

	/* should never get here....*/

	movhi	r2, %call_hiadj(abort)

	addi	r2, r2, %call_lo(abort)

	add	r2, r2, r22

	ldw	r2, 0(r2)

	callr	r2

/* Define a symbol for the first piece of initialized data.  */

	.data

	.globl __data_start

__data_start:

	.long 0

	.weak data_start

	data_start = __data_start