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Diffstat (limited to 'libgloss/nds32/crt0.S')
| -rw-r--r-- | libgloss/nds32/crt0.S | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/libgloss/nds32/crt0.S b/libgloss/nds32/crt0.S new file mode 100644 index 000000000..d12be761f --- /dev/null +++ b/libgloss/nds32/crt0.S @@ -0,0 +1,116 @@ +/* +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 |