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1da177e4 LT |
1 | /* |
2 | * Copyright (C) Paul Mackerras 1997. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License | |
6 | * as published by the Free Software Foundation; either version | |
7 | * 2 of the License, or (at your option) any later version. | |
8 | * | |
9 | * NOTE: this code runs in 32 bit mode and is packaged as ELF32. | |
10 | */ | |
11 | ||
decd300b | 12 | #include "ppc_asm.h" |
1da177e4 LT |
13 | |
14 | .text | |
15 | .globl _start | |
16 | _start: | |
17 | lis r9,_start@h | |
18 | lis r8,_etext@ha | |
19 | addi r8,r8,_etext@l | |
20 | 1: dcbf r0,r9 | |
21 | icbi r0,r9 | |
22 | addi r9,r9,0x20 | |
23 | cmplwi 0,r9,8 | |
24 | blt 1b | |
25 | sync | |
26 | isync | |
27 | ||
28 | ## Clear out the BSS as per ANSI C requirements | |
29 | ||
30 | lis r7,_end@ha | |
31 | addi r7,r7,_end@l # r7 = &_end | |
32 | lis r8,__bss_start@ha # | |
33 | addi r8,r8,__bss_start@l # r8 = &_bss_start | |
34 | ||
35 | ## Determine how large an area, in number of words, to clear | |
36 | ||
37 | subf r7,r8,r7 # r7 = &_end - &_bss_start + 1 | |
38 | addi r7,r7,3 # r7 += 3 | |
39 | srwi. r7,r7,2 # r7 = size in words. | |
40 | beq 3f # If the size is zero, don't bother | |
41 | addi r8,r8,-4 # r8 -= 4 | |
42 | mtctr r7 # SPRN_CTR = number of words to clear | |
43 | li r0,0 # r0 = 0 | |
44 | 2: stwu r0,4(r8) # Clear out a word | |
45 | bdnz 2b # Keep clearing until done | |
46 | 3: | |
47 | b start | |
48 |