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68020
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memcpy.s

memcpy.s 1.2 KB
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  1. 	TEXT	memcpy(SB), $0
    2. 

  2. 

  3. 	MOVL	n+8(FP),R0
    4. 

  4. 	BEQ	return
    5. 

  5. 	BGT	ok
    6. 

  6. 	MOVL	0, R0
    7. 

  7. ok:
    8. 

  8. 	MOVL	s1+0(FP),A2
    9. 

  9. 	MOVL	s2+4(FP),A1
    10. 

  10. 

  11. 	CMPL	A2,A1
    12. 

  12. 	BHI	back
    13. 

  13. 

  14. /*
    15. 

  15.  * speed depends on source allignment
    16. 

  16.  * destination allignment is secondary
    17. 

  17.  * byte-at-a-time foreward copy to
    18. 

  18.  * get source (A1) alligned.
    19. 

  19.  */
    20. 

  20. f1:
    21. 

  21. 	MOVL	A1, R1
    22. 

  22. 	ANDL	$3, R1
    23. 

  23. 	BEQ	f2
    24. 

  24. 	SUBL	$1, R0
    25. 

  25. 	BLT	return
    26. 

  26. 	MOVB	(A1)+, (A2)+
    27. 

  27. 	BRA	f1
    28. 

  28. /*
    29. 

  29.  * quad-long-at-a-time forward copy
    30. 

  30.  */
    31. 

  31. f2:
    32. 

  32. 	SUBL	$16, R0
    33. 

  33. 	BLT	f3
    34. 

  34. 	MOVL	(A1)+, (A2)+
    35. 

  35. 	MOVL	(A1)+, (A2)+
    36. 

  36. 	MOVL	(A1)+, (A2)+
    37. 

  37. 	MOVL	(A1)+, (A2)+
    38. 

  38. 	BRA	f2
    39. 

  39. 

  40. /*
    41. 

  41.  * cleanup byte-at-a-time
    42. 

  42.  */
    43. 

  43. f3:
    44. 

  44. 	ADDL	$15, R0
    45. 

  45. 	BLT	return
    46. 

  46. f4:
    47. 

  47. 	MOVB	(A1)+, (A2)+
    48. 

  48. 	SUBL	$1, R0
    49. 

  49. 	BGE	f4
    50. 

  50. 	BRA	return
    51. 

  51. 

  52. return:
    53. 

  53. 	MOVL	s1+0(FP),R0
    54. 

  54. 	RTS
    55. 

  55. 

  56. /*
    57. 

  57.  * everything the same, but
    58. 

  58.  * copy backwards
    59. 

  59.  */
    60. 

  60. back:
    61. 

  61. 	ADDL	R0, A1
    62. 

  62. 	ADDL	R0, A2
    63. 

  63. 

  64. /*
    65. 

  65.  * byte-at-a-time backward copy to
    66. 

  66.  * get source (A1) alligned.
    67. 

  67.  */
    68. 

  68. b1:
    69. 

  69. 	MOVL	A1, R1
    70. 

  70. 	ANDL	$3, R1
    71. 

  71. 	BEQ	b2
    72. 

  72. 	SUBL	$1, R0
    73. 

  73. 	BLT	return
    74. 

  74. 	MOVB	-(A1), -(A2)
    75. 

  75. 	BRA	b1
    76. 

  76. /*
    77. 

  77.  * quad-long-at-a-time backward copy
    78. 

  78.  */
    79. 

  79. b2:
    80. 

  80. 	SUBL	$16, R0
    81. 

  81. 	BLT	b3
    82. 

  82. 	MOVL	-(A1), -(A2)
    83. 

  83. 	MOVL	-(A1), -(A2)
    84. 

  84. 	MOVL	-(A1), -(A2)
    85. 

  85. 	MOVL	-(A1), -(A2)
    86. 

  86. 	BRA	b2
    87. 

  87. 

  88. /*
    89. 

  89.  * cleanup byte-at-a-time backward
    90. 

  90.  */
    91. 

  91. b3:
    92. 

  92. 	ADDL	$15, R0
    93. 

  93. 	BLT	return
    94. 

  94. b4:
    95. 

  95. 	MOVB	-(A1), -(A2)
    96. 

  96. 	SUBL	$1, R0
    97. 

  97. 	BGE	b4
    98. 

  98. 	BRA	return
    99.