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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:15:05 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:15:05 +0000
commit46651ce6fe013220ed397add242004d764fc0153 (patch)
tree6e5299f990f88e60174a1d3ae6e48eedd2688b2b /src/include/storage/off.h
parentInitial commit. (diff)
downloadpostgresql-14-upstream.tar.xz
postgresql-14-upstream.zip
Adding upstream version 14.5.upstream/14.5upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/include/storage/off.h')
-rw-r--r--src/include/storage/off.h57
1 files changed, 57 insertions, 0 deletions
diff --git a/src/include/storage/off.h b/src/include/storage/off.h
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+++ b/src/include/storage/off.h
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+/*-------------------------------------------------------------------------
+ *
+ * off.h
+ * POSTGRES disk "offset" definitions.
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/off.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef OFF_H
+#define OFF_H
+
+#include "storage/itemid.h"
+/*
+ * OffsetNumber:
+ *
+ * this is a 1-based index into the linp (ItemIdData) array in the
+ * header of each disk page.
+ */
+typedef uint16 OffsetNumber;
+
+#define InvalidOffsetNumber ((OffsetNumber) 0)
+#define FirstOffsetNumber ((OffsetNumber) 1)
+#define MaxOffsetNumber ((OffsetNumber) (BLCKSZ / sizeof(ItemIdData)))
+
+/* ----------------
+ * support macros
+ * ----------------
+ */
+
+/*
+ * OffsetNumberIsValid
+ * True iff the offset number is valid.
+ */
+#define OffsetNumberIsValid(offsetNumber) \
+ ((bool) ((offsetNumber != InvalidOffsetNumber) && \
+ (offsetNumber <= MaxOffsetNumber)))
+
+/*
+ * OffsetNumberNext
+ * OffsetNumberPrev
+ * Increments/decrements the argument. These macros look pointless
+ * but they help us disambiguate the different manipulations on
+ * OffsetNumbers (e.g., sometimes we subtract one from an
+ * OffsetNumber to move back, and sometimes we do so to form a
+ * real C array index).
+ */
+#define OffsetNumberNext(offsetNumber) \
+ ((OffsetNumber) (1 + (offsetNumber)))
+#define OffsetNumberPrev(offsetNumber) \
+ ((OffsetNumber) (-1 + (offsetNumber)))
+
+#endif /* OFF_H */