diff --git a/a8/uuid.cc b/a8/uuid.cc
index 800405e..e79b8f3 100644
--- a/a8/uuid.cc
+++ b/a8/uuid.cc
@@ -10,14 +10,20 @@ namespace a8
     namespace uuid
     {
 
+        long long SnowFlake::FetchTime(long long value)
+        {
+            return (value >> 22)  + a8::uuid::A8_EPOCH;
+        }
+
         int SnowFlake::FetchMachineId(long long value)
         {
-            long long machineid = (value >> 12) & (1023);
+            long long machineid = (value >> SEQUNCE_ID_BIT_NUM) & (MAX_MACHINE_ID);
             return machineid;
         }
 
-        SnowFlake::SnowFlake()
+        int SnowFlake::FetchSequnceId(long long value)
         {
+            return value & MAX_SEQUNCE_ID;
         }
 
         long long SnowFlake::Generate()
@@ -26,7 +32,7 @@ namespace a8
             long long time = a8::GetMilliSecond();
             if (time == last_generate_tick) {//同一微妙内
                 sequence_id++;
-                if (sequence_id >= 0x1000) { //计数已经用完
+                if (sequence_id >= MAX_SEQUNCE_ID) { //计数已经用完
                     while (time <= last_generate_tick) {
                         ::usleep(1);
                         time = a8::GetMilliSecond();
@@ -43,16 +49,20 @@ namespace a8
             // 保留后41位时间
             value = time << 22;
 
-            // 中间10位是机器ID
-            value |= (machine_id & 0x3FF) << 12;
+            // 中间12位是机器ID
+            value |= (machine_id & MAX_MACHINE_ID) << SEQUNCE_ID_BIT_NUM;
+
+            // 最后10位是sequenceID
+            value |= sequence_id & MAX_SEQUNCE_ID;
 
-            // 最后12位是sequenceID
-            value |= sequence_id & 0xFFF;
             return value;
         }
 
         void SnowFlake::SetMachineId(unsigned short machineid)
         {
+            if (machineid > MAX_MACHINE_ID || machineid < 1) {
+                abort();
+            }
             machine_id = machineid;
         }
     }
diff --git a/a8/uuid.h b/a8/uuid.h
index 9c9fc6b..d0b3637 100644
--- a/a8/uuid.h
+++ b/a8/uuid.h
@@ -1,5 +1,5 @@
-#ifndef A8_UUID_HPP
-#define A8_UUID_HPP
+#ifndef A8_UUID_H
+#define A8_UUID_H
 
 namespace a8
 {
@@ -7,21 +7,27 @@ namespace a8
     {
         const long long A8_EPOCH = 1419120000000LL;
 
-        //毫秒级时间41位+机器ID 10位+毫秒内序列12
+        const int MACHINE_ID_BIT_NUM = 12;
+        const int SEQUNCE_ID_BIT_NUM = 10;
+        const int MAX_MACHINE_ID = (1 << MACHINE_ID_BIT_NUM) - 1; //oldvalue: 0x3FF
+        const int MAX_SEQUNCE_ID = (1 << SEQUNCE_ID_BIT_NUM) - 1; //oldvalue: 0xFFF
+
+        //毫秒级时间41位+机器ID 12位+毫秒内序列10
         class SnowFlake
         {
         public:
+            static long long FetchTime(long long value);
             static int FetchMachineId(long long value);
+            static int FetchSequnceId(long long value);
 
         public:
-            SnowFlake();
 
             long long Generate();
             void SetMachineId(unsigned short machineid);
 
         private:
-            unsigned short machine_id = 0; //10 bit
-            unsigned short sequence_id = 0; //12 bit
+            unsigned short machine_id = 0; //12 bit
+            unsigned short sequence_id = 0; //10 bit
             long long last_generate_tick = 0;
         };
     }
diff --git a/test/main.cc b/test/main.cc
index fed388d..d631829 100644
--- a/test/main.cc
+++ b/test/main.cc
@@ -3,6 +3,7 @@
 #include <a8/a8.h>
 #include <a8/pyengine.h>
 #include <a8/stringlist.h>
+#include <a8/uuid.h>
 #include "websocket_test.h"
 #include "xml_test.h"
 
@@ -31,6 +32,12 @@ void testpy()
 
 int main(int argc, char* argv[])
 {
+    a8::uuid::SnowFlake uuid;
+    uuid.SetMachineId(a8::uuid::MAX_MACHINE_ID);
+    long long id = uuid.Generate();
+    long long time = a8::uuid::SnowFlake::FetchTime(id);
+    int mac_id = a8::uuid::SnowFlake::FetchMachineId(id);
+    int seq_id = a8::uuid::SnowFlake::FetchSequnceId(id);
     testpy();
     #if 0
     a8::PyEngine pyengine;