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9304f876 | 1 | /* The startup code sample of Andes NDS32 cpu for GNU compiler |
7adcbafe | 2 | Copyright (C) 2012-2022 Free Software Foundation, Inc. |
9304f876 CJW |
3 | Contributed by Andes Technology Corporation. |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it | |
8 | under the terms of the GNU General Public License as published | |
9 | by the Free Software Foundation; either version 3, or (at your | |
10 | option) any later version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT | |
13 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY | |
14 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public | |
15 | License for more details. | |
16 | ||
17 | Under Section 7 of GPL version 3, you are granted additional | |
18 | permissions described in the GCC Runtime Library Exception, version | |
19 | 3.1, as published by the Free Software Foundation. | |
20 | ||
21 | You should have received a copy of the GNU General Public License and | |
22 | a copy of the GCC Runtime Library Exception along with this program; | |
23 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
24 | <http://www.gnu.org/licenses/>. */ | |
25 | ||
26 | !!============================================================================== | |
27 | !! | |
28 | !! crtzero.S | |
29 | !! | |
30 | !! This is JUST A SAMPLE of nds32 startup code !! | |
31 | !! You can refer this content and implement | |
32 | !! the actual one in newlib/mculib. | |
33 | !! | |
34 | !!============================================================================== | |
35 | ||
36 | !!------------------------------------------------------------------------------ | |
37 | !! Jump to start up code | |
38 | !!------------------------------------------------------------------------------ | |
39 | .section .nds32_init, "ax" | |
40 | j _start | |
41 | ||
42 | !!------------------------------------------------------------------------------ | |
43 | !! Startup code implementation | |
44 | !!------------------------------------------------------------------------------ | |
45 | .section .text | |
46 | .global _start | |
47 | .weak _SDA_BASE_ | |
48 | .weak _FP_BASE_ | |
49 | .align 2 | |
50 | .func _start | |
51 | .type _start, @function | |
52 | _start: | |
53 | .L_fp_gp_lp_init: | |
54 | la $fp, _FP_BASE_ ! init $fp | |
55 | la $gp, _SDA_BASE_ ! init $gp for small data access | |
56 | movi $lp, 0 ! init $lp | |
57 | ||
58 | .L_stack_init: | |
59 | la $sp, _stack ! init $sp | |
60 | movi $r0, -8 ! align $sp to 8-byte (use 0xfffffff8) | |
61 | and $sp, $sp, $r0 ! align $sp to 8-byte (filter out lower 3-bit) | |
62 | ||
63 | .L_bss_init: | |
64 | ! clear BSS, this process can be 4 time faster if data is 4 byte aligned | |
65 | ! if so, use swi.p instead of sbi.p | |
66 | ! the related stuff are defined in linker script | |
67 | la $r0, _edata ! get the starting addr of bss | |
68 | la $r2, _end ! get ending addr of bss | |
69 | beq $r0, $r2, .L_call_main ! if no bss just do nothing | |
70 | movi $r1, 0 ! should be cleared to 0 | |
71 | .L_clear_bss: | |
72 | sbi.p $r1, [$r0], 1 ! Set 0 to bss | |
73 | bne $r0, $r2, .L_clear_bss ! Still bytes left to set | |
74 | ||
75 | !.L_stack_heap_check: | |
76 | ! la $r0, _end ! init heap_end | |
77 | ! s.w $r0, heap_end ! save it | |
78 | ||
79 | ||
80 | !.L_init_argc_argv: | |
81 | ! ! argc/argv initialization if necessary; default implementation is in crt1.o | |
82 | ! la $r9, _arg_init ! load address of _arg_init? | |
83 | ! beqz $r9, .L4 ! has _arg_init? no, go check main() | |
84 | ! addi $sp, $sp, -512 ! allocate space for command line + arguments | |
85 | ! move $r6, $sp ! r6 = buffer addr of cmd line | |
86 | ! move $r0, $r6 ! r0 = buffer addr of cmd line | |
87 | ! syscall 6002 ! get cmd line | |
88 | ! move $r0, $r6 ! r0 = buffer addr of cmd line | |
89 | ! addi $r1, $r6, 256 ! r1 = argv | |
90 | ! jral $r9 ! init argc/argv | |
91 | ! addi $r1, $r6, 256 ! r1 = argv | |
92 | ||
93 | .L_call_main: | |
94 | ! call main() if main() is provided | |
95 | la $r15, main ! load address of main | |
96 | jral $r15 ! call main | |
97 | ||
98 | .L_terminate_program: | |
99 | syscall 0x1 ! use syscall 0x1 to terminate program | |
100 | .size _start, .-_start | |
101 | .end | |
102 | ||
103 | !! ------------------------------------------------------------------------ |