From f74c90da9c81f2030698346c4b4bbc1af3dc2df8 Mon Sep 17 00:00:00 2001
From: Christian Pointner <equinox@anytun.org>
Date: Fri, 13 Oct 2017 22:30:44 +0200
Subject: checkAndSet works now in any case

---
 satp/sequence-window.go      | 24 ++++++++++++++++++++----
 satp/sequence-window_test.go | 11 +++++++++--
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/satp/sequence-window.go b/satp/sequence-window.go
index f529231..9fa4385 100644
--- a/satp/sequence-window.go
+++ b/satp/sequence-window.go
@@ -139,7 +139,23 @@ func (w *SequenceWindow) checkAndSet(sequenceNumber uint32) bool {
 }
 
 func (w *SequenceWindow) advanceTop(newTop uint32) {
-	// TODO: implement this
+	oldIdx := int(w.top() / 32)
+	newIdx := int(newTop / 32)
+	diff := newIdx - oldIdx
+	if oldIdx > newIdx {
+		diff = oldIdx - newIdx
+	}
+	oldHeadSlice := uint32(w.head)
+	w.head = uint64(newTop) << 32
+	for i := len(w.body) - 1; i >= 0; i-- {
+		if i < (diff - 1) {
+			w.body[i] = 0
+		} else if i < diff {
+			w.body[i] = oldHeadSlice
+		} else {
+			w.body[i] = w.body[i-diff]
+		}
+	}
 }
 
 func (w *SequenceWindow) top() uint32 {
@@ -182,10 +198,10 @@ func (w *SequenceWindow) CheckAndSet(sequenceNumber uint32) bool {
 	if lt && d > uint32(w.size) {
 		return false
 	}
-	if lt || top/32 == sequenceNumber/32 {
-		return w.checkAndSet(sequenceNumber)
+	if lt || top/32 == (sequenceNumber+1)/32 {
+		result := w.checkAndSet(sequenceNumber)
+		return result
 	}
-
 	// TODO: only now we would need the writers lock
 	w.advanceTop(sequenceNumber + 1)
 	return w.checkAndSet(sequenceNumber)
diff --git a/satp/sequence-window_test.go b/satp/sequence-window_test.go
index 91211cd..41ee713 100644
--- a/satp/sequence-window_test.go
+++ b/satp/sequence-window_test.go
@@ -196,12 +196,18 @@ func TestSequenceWindowCheckAndSet(t *testing.T) {
 	}{
 		{0, 0, []uint32{0, 1, 2, 3, 4}, true},
 		{0, 0, []uint32{^uint32(0)}, true},
+		{1, 0, []uint32{0}, true},
 		{10, 0, []uint32{^uint32(0)}, false},
-		{10, 20, []uint32{^uint32(0), 5, 9, 10}, false},
+		{10, 20, []uint32{^uint32(0), 5, 9, 10, 12, 13}, false},
+		{10, 20, []uint32{20, 23, 31, 32, 35}, true},
 		{32, 0, []uint32{0, 1, 2, 3, 4}, true},
 		{32, 10, []uint32{0, 1, 2, 3, 4}, false},
 		{32, 10, []uint32{10, 11, 12, 13, 14}, true},
 		{32, 0, []uint32{10, 17, 23, 0, 1, 18, 9, 8, 31}, true},
+		{32, 30, []uint32{30, 31, 32, 33, 34}, true},
+		{32, 0, []uint32{95, 100, 96, 97, 99, 98}, true},
+		{50, 0, []uint32{31, 32, 35, 33, 34, 64}, true},
+		{30, ^uint32(0) - 10, []uint32{0, 1, 2, 3, ^uint32(0), ^uint32(0) - 2}, true},
 	}
 
 	for _, vector := range testvectors {
@@ -209,12 +215,13 @@ func TestSequenceWindowCheckAndSet(t *testing.T) {
 		if err != nil {
 			t.Fatal("unexpected error:", err)
 		}
+		t.Logf("--------------, %v", w)
 		for _, seq := range vector.seqs {
 			result := w.CheckAndSet(seq)
 			if result != vector.result {
 				t.Fatalf("check-and-set %d on %s returned %v but should be %v", seq, w, result, vector.result)
 			}
-			t.Log(w)
+			t.Logf("chk %10d, %v", seq, w)
 		}
 	}
 }
-- 
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