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/*
Copyright (c) 2013-2014 Andes Technology Corporation.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
The name of the company may not be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL RED HAT INCORPORATED BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
##==============================================================================
##
## crt0.S
##
## nds32 startup code
##
##==============================================================================
##------------------------------------------------------------------------------
## Vector table setup
##------------------------------------------------------------------------------
.section .nds32_init, "ax"
j _start
##------------------------------------------------------------------------------
## Startup code implementation
##------------------------------------------------------------------------------
.section .text
.weak _SDA_BASE_
.global _start
.type _start, @function
.align 2
_start:
/* The initialization sequence really does matter !!!
The global pointer must be
initialized precedence over all others. */
.L_init_gp:
/* Initialization for global pointer. The symbol _SDA_BASE_ is
determined by Linker. SDA stands for Small Data Access. */
la $gp, _SDA_BASE_
.L_init_sp:
/* Initialization for stack pointe. The symbol _stack is defined
in linker script. Make sure $sp is 8-byte aligned. */
la $sp, _stack
#if __NDS32_ISA_V3__
bitci $sp, $sp, #7
#else
movi $r0, #-8 /* Set $r0 as 0xFFFFFFF8. */
and $sp, $sp, $r0
#endif
#if __NDS32_EX9_EXT__
.L_init_itb:
/* Initialization for Instruction Table Base (ITB).
The symbol $_ITB_BASE_ is determined by Linker.
Set $ITB only if MSC_CFG.EIT (cr4.b'24) is set. */
mfsr $r0, $MSC_CFG
srli $r0, $r0, 24
andi $r0, $r0, 0x1
beqz $r0, .L_zero_out_bss /* Fall through ? */
la $r0, $_ITB_BASE_
mtusr $r0, $ITB
#endif
.L_zero_out_bss:
/* Zero out the bss section.
Equivalence C code for follow part:
if (_end == _edata) goto .L_call_main
unsinged int *ptr = _edata;
while (ptr != _end)
*ptr++ = 0
$r0 = ptr/_edata
$r1 = _end
$r2 = 0
*/
la $r0, _edata
la $r1, _end
movi $r2, #0
beq $r0, $r1, .L_call_main /* Branch if no bss. */
.Lword_clear:
swi.bi $r2, [$r0], #4
bne $r0, $r1, .Lword_clear
.L_call_main:
/* Prepare argc/argv/env for main function.
Since there is no operating system so far,
we set $r0, $r1, and $r2 to be zero.
Note: $r2 already set to zero in line 84. */
movi $r0, 0
movi $r1, 0
/* Call 'main'. */
bal main
.L_terminate_program:
/* There are two ways to terminate program:
1. User "syscall 0x1" directly.
2. Call exit. The return value $r0 from main() is
implicitly passed as argument.
Currently, we use option 2 as a solution to follow C99 5.1.2.2.3,
but aware that general exit() will do some cleanup procedures
which may result in large-memory-footprints. */
bal exit
.L_forever_loop:
/* Should never return here. */
b .L_forever_loop
.size _start, .-_start
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