claude go reimplement

internal/kjv/mt.go

@@ -0,0 +1,86 @@
+package kjv
+
+// MT19937 seeded with init_by_array from one integer, and a choice made by
+// rejection sampling over its bits, so the verse of the day for any given date
+// never changes.
+
+type mtRandom struct {
+	mt  [624]uint32
+	idx int
+}
+
+func newMTRandom(seed uint32) *mtRandom {
+	r := &mtRandom{}
+	r.initGenrand(19650218)
+	key := []uint32{seed}
+	i, j := 1, 0
+	k := max(624, len(key))
+	for ; k > 0; k-- {
+		r.mt[i] = (r.mt[i] ^ ((r.mt[i-1] ^ (r.mt[i-1] >> 30)) * 1664525)) + key[j] + uint32(j)
+		i++
+		j++
+		if i >= 624 {
+			r.mt[0] = r.mt[623]
+			i = 1
+		}
+		if j >= len(key) {
+			j = 0
+		}
+	}
+	for k = 623; k > 0; k-- {
+		r.mt[i] = (r.mt[i] ^ ((r.mt[i-1] ^ (r.mt[i-1] >> 30)) * 1566083941)) - uint32(i)
+		i++
+		if i >= 624 {
+			r.mt[0] = r.mt[623]
+			i = 1
+		}
+	}
+	r.mt[0] = 0x80000000
+	r.idx = 624
+	return r
+}
+
+func (r *mtRandom) initGenrand(s uint32) {
+	r.mt[0] = s
+	for i := 1; i < 624; i++ {
+		r.mt[i] = 1812433253*(r.mt[i-1]^(r.mt[i-1]>>30)) + uint32(i)
+	}
+	r.idx = 624
+}
+
+func (r *mtRandom) next() uint32 {
+	if r.idx >= 624 {
+		for k := 0; k < 624; k++ {
+			y := (r.mt[k] & 0x80000000) | (r.mt[(k+1)%624] & 0x7fffffff)
+			v := r.mt[(k+397)%624] ^ (y >> 1)
+			if y&1 != 0 {
+				v ^= 0x9908b0df
+			}
+			r.mt[k] = v
+		}
+		r.idx = 0
+	}
+	y := r.mt[r.idx]
+	r.idx++
+	y ^= y >> 11
+	y ^= (y << 7) & 0x9d2c5680
+	y ^= (y << 15) & 0xefc60000
+	y ^= y >> 18
+	return y
+}
+
+// choiceIndex is random.choice's _randbelow(n) for n < 2**32.
+func (r *mtRandom) choiceIndex(n int) int {
+	if n <= 0 {
+		return 0
+	}
+	k := 0
+	for v := n; v > 0; v >>= 1 {
+		k++
+	}
+	for {
+		if x := int(r.next() >> (32 - k)); x < n {
+			return x
+		}
+	}
+}