139 lines
4.3 KiB
ArmAsm
139 lines
4.3 KiB
ArmAsm
/*
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Copyright (c) 2013-2014 Andes Technology Corporation.
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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The name of the company may not be used to endorse or promote
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products derived from this software without specific prior written
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permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL RED HAT INCORPORATED BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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##==============================================================================
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##
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## crt1.S
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##
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## nds32 startup code
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##
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##==============================================================================
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##------------------------------------------------------------------------------
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## Vector table setup
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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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.weak _SDA_BASE_
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.global _start
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.type _start, @function
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.align 2
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_start:
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/* The initialization sequence really does matter !!!
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The global pointer must be
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initialized precedence over all others. */
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.L_init_gp:
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/* Initialization for global pointer. The symbol _SDA_BASE_ is
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determined by Linker. SDA stands for Small Data Access. */
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la $gp, _SDA_BASE_
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.L_init_sp:
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/* Initialization for stack pointe. The symbol _stack is defined
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in linker script. Make sure $sp is 8-byte aligned. */
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la $sp, _stack
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#if __NDS32_ISA_V3__
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bitci $sp, $sp, #7
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#else
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movi $r0, #-8 /* Set $r0 as 0xFFFFFFF8. */
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and $sp, $sp, $r0
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#endif
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#if __NDS32_EX9_EXT__
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.L_init_itb:
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/* Initialization for Instruction Table Base (ITB).
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The symbol $_ITB_BASE_ is determined by Linker.
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Set $ITB only if MSC_CFG.EIT (cr4.b'24) is set. */
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mfsr $r0, $MSC_CFG
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srli $r0, $r0, 24
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andi $r0, $r0, 0x1
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beqz $r0, .L_zero_out_bss /* Fall through ? */
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la $r0, $_ITB_BASE_
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mtusr $r0, $ITB
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#endif
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.L_zero_out_bss:
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/* Zero out the bss section.
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Equivalence C code for follow part:
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if (_end == _edata) goto .L_call_main
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unsinged int *ptr = _edata;
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while (ptr != _end)
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*ptr++ = 0
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$r0 = ptr/_edata
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$r1 = _end
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$r2 = 0
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*/
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la $r0, _edata
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la $r1, _end
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beq $r0, $r1, .L_call_main /* Branch if no bss. */
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movi $r2, #0
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.Lword_clear:
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swi.bi $r2, [$r0], #4
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bne $r0, $r1, .Lword_clear
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.L_call_main:
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/* Call '_init' to invoke constructors. */
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jal _init
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/* Register '_fini' into atexit() to invoke destructors when
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exit() has been reached. */
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la $r0, _fini
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jal atexit
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/* Prepare argc/argv/env for main function.
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Since there is no operating system so far,
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we set $r0, $r1, and $r2 to be zero. */
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movi $r0, 0
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movi $r1, 0
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movi $r2, 0
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/* Call 'main'. */
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bal main
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.L_terminate_program:
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/* There are two ways to terminate program:
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1. User "syscall 0x1" directly.
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2. Call exit. The return value $r0 from main() is
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implicitly passed as argument.
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Currently, we use option 2 as a solution to follow C99 5.1.2.2.3,
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but aware that general exit() will do some cleanup procedures
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which may result in large-memory-footprints. */
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bal exit
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.L_forever_loop:
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/* Should never return here. */
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b .L_forever_loop
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.size _start, .-_start
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