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memmove.s

memmove.s 650 B
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  1. 	TEXT	memmove(SB), $0
    2. 

  2. 

  3. 	MOVL	p1+0(FP), DI
    4. 

  4. 	MOVL	p2+4(FP), SI
    5. 

  5. 	MOVL	n+8(FP), BX
    6. 

  6. 	CMPL	BX, $0
    7. 

  7. 	JGE	ok
    8. 

  8. 	MOVL	$0, SI
    9. 

  9. ok:
    10. 

  10. 	CLD
    11. 

  11. /*
    12. 

  12.  * check and set for backwards
    13. 

  13.  */
    14. 

  14. 	CMPL	SI, DI
    15. 

  15. 	JLS	back
    16. 

  16. /*
    17. 

  17.  * copy whole longs
    18. 

  18.  */
    19. 

  19. 	MOVL	BX, CX
    20. 

  20. 	SHRL	$2, CX
    21. 

  21. 	REP;	MOVSL
    22. 

  22. /*
    23. 

  23.  * copy the rest, by bytes
    24. 

  24.  */
    25. 

  25. 	ANDL	$3, BX
    26. 

  26. 	MOVL	BX, CX
    27. 

  27. 	REP;	MOVSB
    28. 

  28. 

  29. 	MOVL	p+0(FP),AX
    30. 

  30. 	RET
    31. 

  31. /*
    32. 

  32.  * whole thing backwards has
    33. 

  33.  * adjusted addresses
    34. 

  34.  */
    35. 

  35. back:
    36. 

  36. 	ADDL	BX, DI
    37. 

  37. 	ADDL	BX, SI
    38. 

  38. 	SUBL	$4, DI
    39. 

  39. 	SUBL	$4, SI
    40. 

  40. 	STD
    41. 

  41. /*
    42. 

  42.  * copy whole longs
    43. 

  43.  */
    44. 

  44. 	MOVL	BX, CX
    45. 

  45. 	SHRL	$2, CX
    46. 

  46. 	ANDL	$3, BX
    47. 

  47. 	REP;	MOVSL
    48. 

  48. /*
    49. 

  49.  * copy the rest, by bytes
    50. 

  50.  */
    51. 

  51. 	ADDL	$3, DI
    52. 

  52. 	ADDL	$3, SI
    53. 

  53. 	MOVL	BX, CX
    54. 

  54. 	REP;	MOVSB
    55. 

  55. 

  56. 	MOVL	p+0(FP),AX
    57. 

  57. 	RET
    58.