117 lines
3.8 KiB
ArmAsm
117 lines
3.8 KiB
ArmAsm
/*
|
|
Copyright (c) 2013 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_
|
|
.weak _FP_BASE_
|
|
.global _start
|
|
.type _start, @function
|
|
.align 2
|
|
_start:
|
|
.L_fp_gp_lp_init:
|
|
/* Initialization for $fp, $gp, and $lp. The _SDA_BASE_ location
|
|
stands for Small Data Access. */
|
|
la $fp, _FP_BASE_
|
|
la $gp, _SDA_BASE_
|
|
movi $lp, #0
|
|
|
|
.L_stack_init:
|
|
/* Initialization for $sp and make sure it is 8-byte aligned. */
|
|
la $sp, _stack
|
|
movi $r0, #-8 /* Set $r0 as 0xFFFFFFF8. */
|
|
and $sp, $sp, $r0
|
|
|
|
.L_bss_clear:
|
|
/* Clear bss section. */
|
|
la $r3, _end
|
|
la $r0, _edata
|
|
beq $r0, $r3, .L_call_main /* Branch if no bss. */
|
|
sub $r1, $r3, $r0 /* Size to be clear. */
|
|
|
|
/* Set $r2 as how many words to be clear.
|
|
Set $r1 as how many bytes are less than a woard to be clear. */
|
|
srli $r2, $r1, #2
|
|
andi $r1, $r1, #3
|
|
beqz $r3, .Lbyte_clear
|
|
|
|
la $r4, #0x00000000
|
|
.Lword_clear:
|
|
swi.bi $r4, [$r0], #4
|
|
addi $r2, $r2, #-1
|
|
bnez $r2, .Lword_clear /* Loop again ? */
|
|
beqz $r1, .Lend_bss
|
|
|
|
.Lbyte_clear:
|
|
sbi.bi $r4, [$r0], #1
|
|
addi $r1, $r1, #-1
|
|
bnez $r1, .Lbyte_clear
|
|
.Lend_bss:
|
|
|
|
|
|
.L_call_main:
|
|
la $r15, main
|
|
jral $r15
|
|
|
|
.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. */
|
|
la $r15, exit
|
|
jral $r15
|
|
|
|
.L_forever_loop:
|
|
/* Should never return here. */
|
|
b .L_forever_loop
|
|
|
|
.size _start, .-_start
|