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uclibc-ng
/
libc
/
sysdeps
/
linux
/
sh
/
crt0.S

crt0.S 2.1 KB
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  1. /* Startup code for SH & ELF.
    2. 

  2.    Copyright (C) 1999 Free Software Foundation, Inc.
    3. 

  3.    Copyright (C) 2001 Hewlett-Packard Australia
    4. 

  4. 

  5.    This file is part of the GNU C Library.
    6. 

  6. 

  7.    The GNU C Library is free software; you can redistribute it and/or
    8. 

  8.    modify it under the terms of the GNU Library General Public License as
    9. 

  9.    published by the Free Software Foundation; either version 2 of the
    10. 

  10.    License, or (at your option) any later version.
    11. 

  11. 

  12.    The GNU C Library is distributed in the hope that it will be useful,
    13. 

  13.    but WITHOUT ANY WARRANTY; without even the implied warranty of
    14. 

  14.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    15. 

  15.    Library General Public License for more details.
    16. 

  16. 

  17.    You should have received a copy of the GNU Library General Public
    18. 

  18.    License along with the GNU C Library; see the file COPYING.LIB.  If not,
    19. 

  19.    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
    20. 

  20.    Boston, MA 02111-1307, USA.  */
    21. 

  21. 

  22. /* This is the canonical entry point, usually the first thing in the text
    23. 

  23.    segment.
    24. 

  24. 

  25. 	At this entry point, most registers' values are unspecified, except:
    26. 

  26. 

  27.    r4		Contains a function pointer to be registered with `atexit'.
    28. 

  28.    		This is how the dynamic linker arranges to have DT_FINI
    29. 

  29. 		functions called for shared libraries that have been loaded
    30. 

  30. 		before this code runs.
    31. 

  31. 		WARNING: At that stage only static linker is supported. For
    32. 

  32. 		uCLinux we won't bother with r4.
    33. 

  33. 

  34.    sp		The stack contains the arguments and environment:
    35. 

  35.    		0(sp)			argc
    36. 

  36. 		4(sp)			argv[0]
    37. 

  37. 		...
    38. 

  38. 		(4*argc)(sp)		NULL
    39. 

  39. 		(4*(argc+1))(sp)	envp[0]
    40. 

  40. 		...
    41. 

  41. 					NULL
    42. 

  42. */
    43. 

  43. 

  44. 	.text
    45. 

  45. 	.globl _start
    46. 

  46. 	
    47. 

  47. _start:
    48. 

  48. 	/* Clear the frame pointer since this is the outermost frame.  */
    49. 

  49. 	mov #0, r14
    50. 

  50. 

  51. 	/* Pop argc off the stack and save a pointer to argv */
    52. 

  52. 	mov.l @r15+,r4
    53. 

  53. 	mov r15, r5
    54. 

  54. 

  55. 	/* set up the value for the environment pointer
    56. 

  56. 	   r6 = (argc+1)*4+argv
    57. 

  57. 	*/
    58. 

  58. 	mov r4,r6
    59. 

  59. 	add #1,r6
    60. 

  60. 	shll2 r6
    61. 

  61. 	add r5,r6
    62. 

  62. 

  63. 	/* call main */
    64. 

  64. 	mov.l L_main,r1
    65. 

  65. 	jsr @r1
    66. 

  66. 	nop
    67. 

  67. 

  68. 	/* should never get here....*/
    69. 

  69. 	mov.l L_abort,r1
    70. 

  70. 	jsr @r1
    71. 

  71. 	nop
    72. 

  72. 

  73. 	.align	2
    74. 

  74. 

  75. L_main:
    76. 

  76. 	.long	__uClibc_main
    77. 

  77. 

  78. L_abort:
    79. 

  79. 	.long	abort
    80. 

  80. 

  81. 	.data
    82.