Add redis support for distributed caching

vendor/github.com/alicebob/miniredis/v2/fpconv/fp.go

@@ -0,0 +1,96 @@
+package fpconv
+
+import (
+	"math"
+)
+
+type (
+	Fp struct {
+		frac uint64
+		exp  int64
+	}
+)
+
+func build_fp(d float64) Fp {
+	bits := get_dbits(d)
+
+	fp := Fp{
+		frac: bits & fracmask,
+		exp:  int64((bits & expmask) >> 52),
+	}
+
+	if fp.exp != 0 {
+		fp.frac += hiddenbit
+		fp.exp -= expbias
+	} else {
+		fp.exp = -expbias + 1
+	}
+
+	return fp
+}
+
+func normalize(fp Fp) Fp {
+	for (fp.frac & hiddenbit) == 0 {
+		fp.frac <<= 1
+		fp.exp--
+	}
+
+	var shift int64 = 64 - 52 - 1
+	fp.frac <<= shift
+	fp.exp -= shift
+	return fp
+}
+
+func multiply(a, b Fp) Fp {
+	lomask := uint64(0x00000000FFFFFFFF)
+
+	var (
+		ah_bl = uint64((a.frac >> 32) * (b.frac & lomask))
+		al_bh = uint64((a.frac & lomask) * (b.frac >> 32))
+		al_bl = uint64((a.frac & lomask) * (b.frac & lomask))
+		ah_bh = uint64((a.frac >> 32) * (b.frac >> 32))
+	)
+
+	tmp := uint64((ah_bl & lomask) + (al_bh & lomask) + (al_bl >> 32))
+	/* round up */
+	tmp += uint64(1) << 31
+
+	return Fp{
+		ah_bh + (ah_bl >> 32) + (al_bh >> 32) + (tmp >> 32),
+		a.exp + b.exp + 64,
+	}
+}
+
+func get_dbits(d float64) uint64 {
+	return math.Float64bits(d)
+}
+
+func get_normalized_boundaries(fp Fp) (Fp, Fp) {
+	upper := Fp{
+		frac: (fp.frac << 1) + 1,
+		exp:  fp.exp - 1,
+	}
+	for (upper.frac & (hiddenbit << 1)) == 0 {
+		upper.frac <<= 1
+		upper.exp--
+	}
+
+	var u_shift int64 = 64 - 52 - 2
+
+	upper.frac <<= u_shift
+	upper.exp = upper.exp - u_shift
+
+	l_shift := int64(1)
+	if fp.frac == hiddenbit {
+		l_shift = 2
+	}
+
+	lower := Fp{
+		frac: (fp.frac << l_shift) - 1,
+		exp:  fp.exp - l_shift,
+	}
+
+	lower.frac <<= lower.exp - upper.exp
+	lower.exp = upper.exp
+	return lower, upper
+}