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Annotation of coherent/b/lib/libc/gen/rand.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Random number generator, of period 2 ^ 32. Returns random numbers (ints) in
                      3:  *     the interval [0, 2^15-1].
                      4:  * The algorithm used is a linear congruential method, where the internal
                      5:  *     computation is done in unsigned longs (mod 2^32). The numbers from
                      6:  *     this sequence are right shifted 17 bits so that the most random 15
                      7:  *     bits are returned.
                      8:  * All this is from Knuth Vol 2, 2nd ed., ch 3. The choice of multiplier
                      9:  *     is made from the table in 3.3.4.E,  pp102.
                     10:  */
                     11: 
                     12: #define        A       1664525L                /* Multiplicative generator */
                     13: #define        C       907633387L              /* Additive generator */
                     14: 
                     15: 
                     16: static long    seed    = 1;
                     17: 
                     18: srand(n)
                     19: unsigned int n;
                     20: {
                     21:        seed = n;
                     22: }
                     23: 
                     24: rand()
                     25: {
                     26:        seed = seed * A + C;
                     27:        return ((seed >> 17) & 077777);
                     28: }

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