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  1. #define Z IP
  2. #define I FP
  3. #define J LR
  4.  
  5. #define INPUT_VALUE 30
  6.  
  7. ; in C
  8. ; int factorial(int n) {
  9. ; 	if (n <= 1) {
  10. ;		return 1;
  11. ;	} else {
  12. ;		return n * factorial(n-1);
  13. ;	}
  14. ;}
  15.  
  16. ; in DCPU
  17. :factorial
  18. 	@ Store link register on stack
  19. 	SUB SP, 2
  20. 	SET [SP], LR
  21.  
  22. 	@ Store frame pointer on stack
  23. 	SUB SP, 2
  24. 	SET [SP], FP
  25.  
  26. 	@ Set frame pointer to start of frame
  27. 	SET FP, SP
  28.  
  29. 	@ Allocate n on the stack
  30. 	SUB SP, 2
  31. 	SET [SP], A
  32.  
  33. 	@ Load n	
  34. 	SET C, FP
  35. 	SUB C, 2
  36. 	SET C, [C]
  37.  
  38. 	@ compare n and 1
  39. 	IFG C, 1
  40.  
  41. 	@ Handle the else branch
  42. 	SET PC, factorial_recurse
  43.  
  44. 	@ Handle the if branch
  45. 	@ Return 1
  46. 	SET A, 1
  47. 	SET PC, factorial_end
  48.  
  49. :factorial_recurse
  50. 	@ Call factorial with n-1
  51. 	SET A, FP
  52. 	SUB A, 2
  53. 	SET A, [A]
  54. 	SUB A, 1
  55. 	MOV PC, factorial
  56. 	@ Multiply returned value by n and return
  57. 	SET C, FP
  58. 	SUB C, 2
  59. 	SET C, [C]
  60. 	MUL A, C
  61. 	SET PC, factorial_end
  62.  
  63. :factorial_end
  64. 	@ Unwind stack and return
  65. 	SET SP, FP
  66. 	SET FP, [SP]
  67. 	ADD SP, 2
  68. 	SET LR, [SP]
  69. 	SET PC, LR
  70.  
  71. :main
  72. 	@ Push LR to stack
  73. 	SUB SP, 2
  74. 	SET [SP], LR
  75.  
  76. 	@ Call factorial with parameter INPUT_VALUE
  77. 	SET A, INPUT_VALUE
  78. 	SET PC, factorial
  79.  
  80. 	@ Return the value returned by factorial
  81. 	ADD SP, 2
  82. 	SET PC, LR
Not running #stdin #stdout 0s 0KB
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https://ideone.com/K0pvY
language:
Text (text 6.10)
created:
14 years ago
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