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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.
*/
##==============================================================================
##
## crt1.S
##
## nds32 startup code
##
##==============================================================================
#include "syscall_extra.h"
##------------------------------------------------------------------------------
## Vector table setup
##------------------------------------------------------------------------------
.section .nds32_init, "ax"
j _start
##------------------------------------------------------------------------------
## Startup code implementation
##------------------------------------------------------------------------------
.section .text
.weak _SDA_BASE_
.weak _ITB_BASE_
.weak _arg_init
.weak __pre_c_init
.weak __post_c_init
.weak _call_exit
.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_
#if __NDS32_EXT_EX9__
.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, 1f /* Fall through ? */
la $r0, _ITB_BASE_
mtusr $r0, $ITB
1:
#endif
.L_init_sp:
/* Initialization for stack pointer. 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_EXT_FPU_SP__ || __NDS32_EXT_FPU_DP__
.L_init_fpu:
/* Initialize FPU
Set FUCOP_CTL.CP0EN (fucpr.b'0). */
mfsr $r0, $FUCOP_CTL
ori $r0, $r0, 0x1
mtsr $r0, $FUCOP_CTL
dsb
/* According to [bugzilla #9425], set flush-to-zero mode.
That is, set $FPCSR.DNZ(b'12) = 1. */
FMFCSR $r0
ori $r0, $r0, 0x1000
FMTCSR $r0
dsb
#endif
.L_pre_c_init:
! call __pre_c_init if provided
! sample __pre_c_init is in BSP
la $r15, __pre_c_init ! load address of __pre_c_init
beqz $r15, .L_zero_out_bss ! check existence of __pre_c_init
jral $r15 ! pre-c-runtime initialization
.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_cpp_init /* Branch if no bss. */
.Lword_clear:
swi.bi $r2, [$r0], #4
bne $r0, $r1, .Lword_clear
.L_cpp_init:
/* Call '_init' to invoke constructors. */
jal _init
/* Register '_fini' into atexit() to invoke destructors when
exit() has been reached. */
la $r0, _fini
jal atexit
.L_post_c_init:
! call __post_c_init if provided
! no sample __post_c_init is provided
la $r15, __post_c_init ! load address of __post_c_init
beqz $r15, .L_arg_init ! check existence of __post_c_init
jral $r15 ! post-c-runtime initialization
.L_arg_init:
! argc/argv initialization if necessary
la $r7, _arg_init ! get address of _arg_init
beqz $r7, .L_clean_reg ! if there isn't _arg_init, go main
addi $sp, $sp, -512 ! allocate space for command line
! and arguments
move $r6, $sp ! r6 = buffer addr of cmd line
move $r0, $r6 ! r0 = buffer addr of cmd line
syscall SYS_getcmdline ! get cmd line
move $r0, $r6 ! r0 = buffer addr of cmd line
addi $r1, $r6, 256 ! r1 = argv
jral $r7 ! init argc/argv
addi $r1, $r6, 256 ! r1 = argv
b .L_call_main
.L_clean_reg:
/* 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 .L_zero_out_bss: code fragment. */
movi $r0, 0
movi $r1, 0
movi $r2, 0
.L_call_main:
/* Call 'main'. */
bal main
/* Call _call_exit. */
! call _call_exit if necessary; default implementation is in crtexit.c
la $r15, _call_exit ! load address of _call_exit
beqz $r15, .L_terminate_program ! no _call_exit? go exit
jral $r15 ! _call_exit will never return
.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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