From e29eb0041f8ad3984122207c3a4f8203d440ea6c Mon Sep 17 00:00:00 2001
From: Christian Pointner <equinox@anytun.org>
Date: Tue, 19 Sep 2017 21:10:24 +0200
Subject: sequence window partially implemented

---
 satp/sequence-window.go      | 39 +++++++++++++++++--
 satp/sequence-window_test.go | 90 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 125 insertions(+), 4 deletions(-)
 create mode 100644 satp/sequence-window_test.go

diff --git a/satp/sequence-window.go b/satp/sequence-window.go
index c74ca62..94a7b0b 100644
--- a/satp/sequence-window.go
+++ b/satp/sequence-window.go
@@ -32,23 +32,43 @@ package satp
 
 import (
 	"errors"
+	"sync"
+	"sync/atomic"
 )
 
 type SequenceWindow struct {
-	size int
+	size  int
+	head  uint64
+	body  []uint32
+	mutex *sync.RWMutex
+}
+
+func (w *SequenceWindow) Size() int {
+	return w.size
+}
+
+func (w *SequenceWindow) Top() uint32 {
+	if w.size > 0 {
+		w.mutex.RLock()
+		defer w.mutex.RUnlock()
+	}
+	v := atomic.LoadUint64(&w.head)
+	return uint32(v >> 32)
 }
 
 func (w *SequenceWindow) Check(sequenceNumber uint32) (bool, error) {
-	if w.size == 0 {
+	if w.size <= 0 {
 		return false, nil
 	}
+	// TODO: implement this
 	return false, nil
 }
 
 func (w *SequenceWindow) CheckAndSet(sequenceNumber uint32) (bool, error) {
-	if w.size == 0 {
+	if w.size <= 0 {
 		return false, nil
 	}
+	// TODO: implement this
 	return false, nil
 }
 
@@ -56,6 +76,17 @@ func NewSequenceWindow(size int) (w *SequenceWindow, err error) {
 	if size < 0 {
 		return nil, errors.New("invalid sequence window size")
 	}
-	w = &SequenceWindow{size: size}
+	w = &SequenceWindow{size: size, head: 0}
+	if w.size > 0 {
+		bodyLen := (w.size / 32)
+		if (w.size % 32) != 0 {
+			bodyLen++
+		}
+		w.body = make([]uint32, bodyLen, bodyLen)
+		for i := range w.body {
+			w.body[i] = 0
+		}
+		w.mutex = &sync.RWMutex{}
+	}
 	return
 }
diff --git a/satp/sequence-window_test.go b/satp/sequence-window_test.go
new file mode 100644
index 0000000..4fc244a
--- /dev/null
+++ b/satp/sequence-window_test.go
@@ -0,0 +1,90 @@
+//
+// Copyright (c) 2017 anygone contributors (see AUTHORS file)
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice, this
+//   list of conditions and the following disclaimer.
+//
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution.
+//
+// * Neither the name of anygone nor the names of its
+//   contributors may be used to endorse or promote products derived from
+//   this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+
+package satp
+
+import (
+	"testing"
+)
+
+func TestSequenceWindowNew(t *testing.T) {
+	testvectors := []struct {
+		size    int
+		bodyLen int
+		valid   bool
+	}{
+		{-1, 0, false},
+		{0, 0, true},
+		{1, 1, true},
+		{10, 1, true},
+		{32, 1, true},
+		{33, 2, true},
+		{63, 2, true},
+		{64, 2, true},
+		{65, 3, true},
+		{100, 4, true},
+	}
+
+	for _, vector := range testvectors {
+		w, err := NewSequenceWindow(vector.size)
+		if vector.valid {
+			if err != nil {
+				t.Fatal("unexpected error:", err)
+			}
+			if w.Size() != vector.size {
+				t.Fatalf("sequence-window has wrong size, is: %d, should be %d", w.Size(), vector.size)
+			}
+			if w.Top() != 0 {
+				t.Fatalf("sequence-window(%d) top value not 0: 0x%08X", vector.size, w.Top())
+			}
+			if w.head != 0 {
+				t.Fatalf("sequence-window(%d) head not 0: 0x%16X", vector.size, w.head)
+			}
+			bodyLen := len(w.body)
+			if bodyLen != vector.bodyLen {
+				t.Fatalf("sequence-window(%d) body length has invalid length, is: %d, should be %d", vector.size, bodyLen, vector.bodyLen)
+			}
+			isEmpty := true
+			for _, v := range w.body {
+				if v != 0 {
+					isEmpty = false
+				}
+			}
+			if !isEmpty {
+				t.Fatalf("sequence-window(%d) body not empty, is: %v", vector.size, w.body)
+			}
+		} else {
+			if err == nil {
+				t.Fatalf("creating sequence-window(%d) should give an error", vector.size)
+			}
+		}
+	}
+
+}
-- 
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