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arm
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delay.S

delay.S 1.2 KB
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  1. /*
    2. 

  2.  *  linux/arch/arm/lib/delay.S
    3. 

  3.  *
    4. 

  4.  *  Copyright (C) 1995, 1996 Russell King
    5. 

  5.  *
    6. 

  6.  * This program is free software; you can redistribute it and/or modify
    7. 

  7.  * it under the terms of the GNU General Public License version 2 as
    8. 

  8.  * published by the Free Software Foundation.
    9. 

  9.  */
    10. 

  10. #include <linux/linkage.h>
    11. 

  11. #include <asm/assembler.h>
    12. 

  12. 		.text
    13. 

  13. 

  14. LC0:		.word	loops_per_jiffy
    15. 

  15. 

  16. /*
    17. 

  17.  * 0 <= r0 <= 2000
    18. 

  18.  */
    19. 

  19. ENTRY(__udelay)
    20. 

  20. 		mov	r2,     #0x6800
    21. 

  21. 		orr	r2, r2, #0x00db
    22. 

  22. 		mul	r0, r2, r0
    23. 

  23. ENTRY(__const_udelay)				@ 0 <= r0 <= 0x01ffffff
    24. 

  24. 		ldr	r2, LC0
    25. 

  25. 		ldr	r2, [r2]		@ max = 0x0fffffff
    26. 

  26. 		mov	r0, r0, lsr #11		@ max = 0x00003fff
    27. 

  27. 		mov	r2, r2, lsr #11		@ max = 0x0003ffff
    28. 

  28. 		mul	r0, r2, r0		@ max = 2^32-1
    29. 

  29. 		movs	r0, r0, lsr #6
    30. 

  30. 		RETINSTR(moveq,pc,lr)
    31. 

  31. 

  32. /*
    33. 

  33.  * loops = (r0 * 0x10c6 * 100 * loops_per_jiffy) / 2^32
    34. 

  34.  *
    35. 

  35.  * Oh, if only we had a cycle counter...
    36. 

  36.  */
    37. 

  37. 

  38. @ Delay routine
    39. 

  39. ENTRY(__delay)
    40. 

  40. 		subs	r0, r0, #1
    41. 

  41. #if 0
    42. 

  42. 		RETINSTR(movls,pc,lr)
    43. 

  43. 		subs	r0, r0, #1
    44. 

  44. 		RETINSTR(movls,pc,lr)
    45. 

  45. 		subs	r0, r0, #1
    46. 

  46. 		RETINSTR(movls,pc,lr)
    47. 

  47. 		subs	r0, r0, #1
    48. 

  48. 		RETINSTR(movls,pc,lr)
    49. 

  49. 		subs	r0, r0, #1
    50. 

  50. 		RETINSTR(movls,pc,lr)
    51. 

  51. 		subs	r0, r0, #1
    52. 

  52. 		RETINSTR(movls,pc,lr)
    53. 

  53. 		subs	r0, r0, #1
    54. 

  54. 		RETINSTR(movls,pc,lr)
    55. 

  55. 		subs	r0, r0, #1
    56. 

  56. #endif
    57. 

  57. 		bhi	__delay
    58. 

  58. 		RETINSTR(mov,pc,lr)
    59.