init: v1.0.0

grand/drng/internal/util_funcs.go

@@ -0,0 +1,69 @@
+package internal
+
+import (
+	"encoding/binary"
+	"time"
+
+	"xdx.jelly/xgcl/internal"
+)
+
+// var nonceCounter atomic.Int64
+
+// atomic.Int64 only available in go 1.19, so we make a new one.
+type atomicUint64 struct {
+	spin internal.SpinLock
+	n    uint64
+}
+
+var nonceCounter atomicUint64
+
+func (a *atomicUint64) LoadAndAdd(n uint64) uint64 {
+	a.spin.Lock()
+	defer a.spin.Unlock()
+	v := a.n
+	a.n += n
+	return v
+}
+
+// nonce 由时间戳和单调递增的计数器组成
+func Nonce() []byte {
+	out := make([]byte, 16)
+	binary.BigEndian.PutUint64(out, uint64(time.Now().UnixNano()))
+	binary.BigEndian.PutUint64(out[8:], nonceCounter.LoadAndAdd(1))
+	return out
+}
+
+// AddModBytes a = a+b as integer, a,b are bigendian and len(a) >= len(b).
+func AddModBytes(a, b []byte) {
+	var x uint
+
+	x = 0
+	i := len(a) - 1
+	j := len(b) - 1
+	for j >= 0 {
+		x += uint(a[i]) + uint(b[j])
+		a[i] = byte(x)
+		x = x >> 8
+		j--
+		i--
+	}
+	if x == 0 {
+		return
+	}
+	for i >= 0 {
+		a[i] += 1
+		if a[i] != 0 {
+			break
+		}
+	}
+}
+
+func IncBytes(a []byte) {
+	i := len(a) - 1
+	for i >= 0 {
+		a[i]++
+		if a[i] != 0 {
+			break
+		}
+	}
+}