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Merge branch 'xoroshiro128plus'

--- a/src/z-rand.c

+++ b/src/z-rand.c

		@@ -70,6 +70,65 @@ u32b Rand_state[RAND_DEG] = {
70	70	};
71	71
72	72
	73	+typedef struct {
	74	+ u32b dw[2];
	75	+} u64b;
	76	+
	77	+static u64b u64b_xor(u64b a, u64b b)
	78	+{
	79	+ u64b result;
	80	+
	81	+ result.dw[0] = a.dw[0] ^ b.dw[0];
	82	+ result.dw[1] = a.dw[1] ^ b.dw[1];
	83	+
	84	+ return result;
	85	+}
	86	+
	87	+static u64b u64b_shiftl(u64b x, int k)
	88	+{
	89	+ u64b result;
	90	+
	91	+ if (k < 32) {
	92	+ result.dw[1] = (x.dw[1] << k) \| (x.dw[0] >> (32 - k));
	93	+ result.dw[0] = (x.dw[0] << k);
	94	+ }
	95	+ else {
	96	+ result.dw[1] = (x.dw[0] << (k - 32));
	97	+ result.dw[0] = 0;
	98	+ }
	99	+
	100	+ return result;
	101	+}
	102	+
	103	+static u64b u64b_rotl(u64b x, int k)
	104	+{
	105	+ u64b result;
	106	+
	107	+ if (k < 32) {
	108	+ result.dw[0] = (x.dw[0] << k) \| (x.dw[1] >> (32 - k));
	109	+ result.dw[1] = (x.dw[1] << k) \| (x.dw[0] >> (32 - k));
	110	+ }
	111	+ else {
	112	+ result.dw[0] = (x.dw[0] >> (64 - k)) \| (x.dw[1] << (k - 32));
	113	+ result.dw[1] = (x.dw[1] >> (64 - k)) \| (x.dw[0] << (k - 32));
	114	+ }
	115	+
	116	+ return result;
	117	+}
	118	+
	119	+static u64b u64b_add(u64b a, u64b b)
	120	+{
	121	+ u64b result;
	122	+
	123	+ result.dw[0] = a.dw[0] + b.dw[0];
	124	+ result.dw[1] = a.dw[1] + b.dw[1];
	125	+
	126	+ if (result.dw[0] < a.dw[0])
	127	+ result.dw[1] ++;
	128	+
	129	+ return result;
	130	+}
	131	+
73	132	/*
74	133	* Initialize Xorshift Algorithm state
75	134	*/

		@@ -84,6 +143,7 @@ static void Rand_Xorshift_seed(u32b seed, u32b* state)
84	143	}
85	144	}
86	145
	146	+#if 0
87	147	/*
88	148	* Xorshift Algorithm
89	149	*/

		@@ -99,6 +159,23 @@ static u32b Rand_Xorshift(u32b* state)
99	159
100	160	return state[3];
101	161	}
	162	+#endif
	163	+
	164	+/*
	165	+ * Xoroshiro128+ Algorithm
	166	+ */
	167	+static u32b Rand_Xoroshiro128plus(u32b* state)
	168	+{
	169	+ const u64b s0 = ((u64b)state);
	170	+ u64b s1 = ((u64b)state + 1);
	171	+ const u64b result = u64b_add(s0, s1);
	172	+
	173	+ s1 = u64b_xor(s0, s1);
	174	+ ((u64b)state) = u64b_xor(u64b_xor(u64b_rotl(s0, 55), s1), u64b_shiftl(s1, 14));
	175	+ ((u64b)state + 1) = u64b_rotl(s1, 36);
	176	+
	177	+ return result.dw[0];
	178	+}
102	179
103	180	static const u32b Rand_Xorshift_max = 0xFFFFFFFF;
104	181

		@@ -189,7 +266,7 @@ static s32b Rand_div_impl(s32b m, u32b* state)
189	266	past = scaling * m;
190	267
191	268	do {
192		- ret = Rand_Xorshift(state);
	269	+ ret = Rand_Xoroshiro128plus(state);
193	270	} while (ret >= past);
194	271
195	272	return ret / scaling;