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/* The startup code sample of Andes NDS32 cpu for GNU compiler
Copyright (C) 2012-2018 Free Software Foundation, Inc.
Contributed by Andes Technology Corporation.
This file is part of GCC.
GCC 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, or (at your
option) any later version.
GCC 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.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
!!==============================================================================
!!
!! crtzero.S
!!
!! This is JUST A SAMPLE of nds32 startup code !!
!! You can refer this content and implement
!! the actual one in newlib/mculib.
!!
!!==============================================================================
!!------------------------------------------------------------------------------
!! Jump to start up code
!!------------------------------------------------------------------------------
.section .nds32_init, "ax"
j _start
!!------------------------------------------------------------------------------
!! Startup code implementation
!!------------------------------------------------------------------------------
.section .text
.global _start
.weak _SDA_BASE_
.weak _FP_BASE_
.align 2
.func _start
.type _start, @function
_start:
.L_fp_gp_lp_init:
la $fp, _FP_BASE_ ! init $fp
la $gp, _SDA_BASE_ ! init $gp for small data access
movi $lp, 0 ! init $lp
.L_stack_init:
la $sp, _stack ! init $sp
movi $r0, -8 ! align $sp to 8-byte (use 0xfffffff8)
and $sp, $sp, $r0 ! align $sp to 8-byte (filter out lower 3-bit)
.L_bss_init:
! clear BSS, this process can be 4 time faster if data is 4 byte aligned
! if so, use swi.p instead of sbi.p
! the related stuff are defined in linker script
la $r0, _edata ! get the starting addr of bss
la $r2, _end ! get ending addr of bss
beq $r0, $r2, .L_call_main ! if no bss just do nothing
movi $r1, 0 ! should be cleared to 0
.L_clear_bss:
sbi.p $r1, [$r0], 1 ! Set 0 to bss
bne $r0, $r2, .L_clear_bss ! Still bytes left to set
!.L_stack_heap_check:
! la $r0, _end ! init heap_end
! s.w $r0, heap_end ! save it
!.L_init_argc_argv:
! ! argc/argv initialization if necessary; default implementation is in crt1.o
! la $r9, _arg_init ! load address of _arg_init?
! beqz $r9, .L4 ! has _arg_init? no, go check main()
! addi $sp, $sp, -512 ! allocate space for command line + arguments
! move $r6, $sp ! r6 = buffer addr of cmd line
! move $r0, $r6 ! r0 = buffer addr of cmd line
! syscall 6002 ! get cmd line
! move $r0, $r6 ! r0 = buffer addr of cmd line
! addi $r1, $r6, 256 ! r1 = argv
! jral $r9 ! init argc/argv
! addi $r1, $r6, 256 ! r1 = argv
.L_call_main:
! call main() if main() is provided
la $r15, main ! load address of main
jral $r15 ! call main
.L_terminate_program:
syscall 0x1 ! use syscall 0x1 to terminate program
.size _start, .-_start
.end
!! ------------------------------------------------------------------------
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