104 lines
3.6 KiB
ArmAsm
104 lines
3.6 KiB
ArmAsm
/* The startup code sample of Andes NDS32 cpu for GNU compiler
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Copyright (C) 2012-2018 Free Software Foundation, Inc.
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Contributed by Andes Technology Corporation.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published
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by the Free Software Foundation; either version 3, or (at your
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option) any later version.
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GCC is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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License for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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!!==============================================================================
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!!
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!! crtzero.S
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!!
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!! This is JUST A SAMPLE of nds32 startup code !!
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!! You can refer this content and implement
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!! the actual one in newlib/mculib.
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!!
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!!==============================================================================
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!!------------------------------------------------------------------------------
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!! Jump to start up code
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!!------------------------------------------------------------------------------
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.section .nds32_init, "ax"
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j _start
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!!------------------------------------------------------------------------------
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!! Startup code implementation
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!!------------------------------------------------------------------------------
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.section .text
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.global _start
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.weak _SDA_BASE_
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.weak _FP_BASE_
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.align 2
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.func _start
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.type _start, @function
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_start:
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.L_fp_gp_lp_init:
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la $fp, _FP_BASE_ ! init $fp
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la $gp, _SDA_BASE_ ! init $gp for small data access
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movi $lp, 0 ! init $lp
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.L_stack_init:
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la $sp, _stack ! init $sp
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movi $r0, -8 ! align $sp to 8-byte (use 0xfffffff8)
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and $sp, $sp, $r0 ! align $sp to 8-byte (filter out lower 3-bit)
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.L_bss_init:
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! clear BSS, this process can be 4 time faster if data is 4 byte aligned
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! if so, use swi.p instead of sbi.p
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! the related stuff are defined in linker script
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la $r0, _edata ! get the starting addr of bss
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la $r2, _end ! get ending addr of bss
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beq $r0, $r2, .L_call_main ! if no bss just do nothing
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movi $r1, 0 ! should be cleared to 0
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.L_clear_bss:
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sbi.p $r1, [$r0], 1 ! Set 0 to bss
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bne $r0, $r2, .L_clear_bss ! Still bytes left to set
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!.L_stack_heap_check:
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! la $r0, _end ! init heap_end
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! s.w $r0, heap_end ! save it
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!.L_init_argc_argv:
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! ! argc/argv initialization if necessary; default implementation is in crt1.o
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! la $r9, _arg_init ! load address of _arg_init?
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! beqz $r9, .L4 ! has _arg_init? no, go check main()
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! addi $sp, $sp, -512 ! allocate space for command line + arguments
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! move $r6, $sp ! r6 = buffer addr of cmd line
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! move $r0, $r6 ! r0 = buffer addr of cmd line
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! syscall 6002 ! get cmd line
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! move $r0, $r6 ! r0 = buffer addr of cmd line
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! addi $r1, $r6, 256 ! r1 = argv
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! jral $r9 ! init argc/argv
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! addi $r1, $r6, 256 ! r1 = argv
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.L_call_main:
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! call main() if main() is provided
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la $r15, main ! load address of main
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jral $r15 ! call main
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.L_terminate_program:
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syscall 0x1 ! use syscall 0x1 to terminate program
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.size _start, .-_start
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.end
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!! ------------------------------------------------------------------------
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