124 lines
4.0 KiB
ArmAsm
124 lines
4.0 KiB
ArmAsm
/*
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Copyright (c) 2013 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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.weak _FP_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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.L_fp_gp_lp_init:
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/* Initialization for $fp, $gp, and $lp. The _SDA_BASE_ location
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stands for Small Data Access. */
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la $fp, _FP_BASE_
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la $gp, _SDA_BASE_
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movi $lp, #0
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.L_stack_init:
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/* Initialization for $sp and make sure it is 8-byte aligned. */
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la $sp, _stack
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movi $r0, #-8 /* Set $r0 as 0xFFFFFFF8. */
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and $sp, $sp, $r0
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.L_bss_clear:
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/* Clear bss section. */
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la $r3, _end
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la $r0, _edata
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beq $r0, $r3, .L_call_main /* Branch if no bss. */
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sub $r1, $r3, $r0 /* Size to be clear. */
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/* Set $r2 as how many words to be clear.
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Set $r1 as how many bytes are less than a woard to be clear. */
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srli $r2, $r1, #2
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andi $r1, $r1, #3
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beqz $r3, .Lbyte_clear
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la $r4, #0x00000000
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.Lword_clear:
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swi.bi $r4, [$r0], #4
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addi $r2, $r2, #-1
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bnez $r2, .Lword_clear /* Loop again ? */
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beqz $r1, .Lend_bss
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.Lbyte_clear:
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sbi.bi $r4, [$r0], #1
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addi $r1, $r1, #-1
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bnez $r1, .Lbyte_clear
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.Lend_bss:
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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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/* Call 'main'. */
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la $r15, main
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jral $r15
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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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la $r15, exit
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jral $r15
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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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