/src/rt/isaac/rand.h

http://github.com/jruderman/rust · C Header · 56 lines · 24 code · 9 blank · 23 comment · 0 complexity · 028dc6b6831999740230b8a84500ba62 MD5 · raw file 

    

  1. /*
    2. 

  2. ------------------------------------------------------------------------------
    3. 

  3. rand.h: definitions for a random number generator
    4. 

  4. By Bob Jenkins, 1996, Public Domain
    5. 

  5. MODIFIED:
    6. 

  6.   960327: Creation (addition of randinit, really)
    7. 

  7.   970719: use context, not global variables, for internal state
    8. 

  8.   980324: renamed seed to flag
    9. 

  9.   980605: recommend RANDSIZL=4 for noncryptography.
    10. 

  10.   010626: note this is public domain
    11. 

  11. ------------------------------------------------------------------------------
    12. 

  12. */
    13. 

  13. #ifndef STANDARD
    14. 

  14. #include "standard.h"
    15. 

  15. #endif
    16. 

  16. 

  17. #ifndef RAND
    18. 

  18. #define RAND
    19. 

  19. #define RANDSIZL   (8)  /* I recommend 8 for crypto, 4 for simulations */
    20. 

  20. #define RANDSIZ    (1<<RANDSIZL)
    21. 

  21. 

  22. /* context of random number generator */
    23. 

  23. struct randctx
    24. 

  24. {
    25. 

  25.   ub4 randcnt;
    26. 

  26.   ub4 randrsl[RANDSIZ];
    27. 

  27.   ub4 randmem[RANDSIZ];
    28. 

  28.   ub4 randa;
    29. 

  29.   ub4 randb;
    30. 

  30.   ub4 randc;
    31. 

  31. };
    32. 

  32. typedef  struct randctx  randctx;
    33. 

  33. 

  34. /*
    35. 

  35. ------------------------------------------------------------------------------
    36. 

  36.  If (flag==TRUE), then use the contents of randrsl[0..RANDSIZ-1] as the seed.
    37. 

  37. ------------------------------------------------------------------------------
    38. 

  38. */
    39. 

  39. void randinit(randctx *r, word flag);
    40. 

  40. 

  41. void isaac(randctx *r);
    42. 

  42. 

  43. 

  44. /*
    45. 

  45. ------------------------------------------------------------------------------
    46. 

  46.  Call isaac_rand(/o_ randctx *r _o/) to retrieve a single 32-bit random value
    47. 

  47. ------------------------------------------------------------------------------
    48. 

  48. */
    49. 

  49. #define isaac_rand(r) \
    50. 

  50.    (!(r)->randcnt-- ? \
    51. 

  51.      (isaac(r), (r)->randcnt=RANDSIZ-1, (r)->randrsl[(r)->randcnt]) : \
    52. 

  52.      (r)->randrsl[(r)->randcnt])
    53. 

  53. 

  54. #endif  /* RAND */
    55.