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+/*****************************************************************************
+
+Copyright (c) 2006, 2009, Oracle and/or its affiliates. All Rights Reserved.
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; version 2 of the License.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA
+
+*****************************************************************************/
+
+/**************************************************//**
+@file include/row0ext.ic
+Caching of externally stored column prefixes
+
+Created September 2006 Marko Makela
+*******************************************************/
+
+#include "rem0types.h"
+#include "btr0types.h"
+
+/********************************************************************//**
+Looks up a column prefix of an externally stored column.
+@return column prefix, or NULL if the column is not stored externally,
+or pointer to field_ref_zero if the BLOB pointer is unset */
+UNIV_INLINE
+const byte*
+row_ext_lookup_ith(
+/*===============*/
+ const row_ext_t* ext, /*!< in/out: column prefix cache */
+ ulint i, /*!< in: index of ext->ext[] */
+ ulint* len) /*!< out: length of prefix, in bytes,
+ at most ext->max_len */
+{
+ ut_ad(ext);
+ ut_ad(len);
+ ut_ad(i < ext->n_ext);
+
+ *len = ext->len[i];
+
+ ut_ad(*len <= ext->max_len);
+ ut_ad(ext->max_len > 0);
+
+ if (*len == 0) {
+ /* The BLOB could not be fetched to the cache. */
+ return(field_ref_zero);
+ } else {
+ return(ext->buf + i * ext->max_len);
+ }
+}
+
+/********************************************************************//**
+Looks up a column prefix of an externally stored column.
+@return column prefix, or NULL if the column is not stored externally,
+or pointer to field_ref_zero if the BLOB pointer is unset */
+UNIV_INLINE
+const byte*
+row_ext_lookup(
+/*===========*/
+ const row_ext_t* ext, /*!< in: column prefix cache */
+ ulint col, /*!< in: column number in the InnoDB
+ table object, as reported by
+ dict_col_get_no(); NOT relative to the
+ records in the clustered index */
+ ulint* len) /*!< out: length of prefix, in bytes,
+ at most ext->max_len */
+{
+ ulint i;
+
+ ut_ad(ext);
+ ut_ad(len);
+
+ for (i = 0; i < ext->n_ext; i++) {
+ if (col == ext->ext[i]) {
+ return(row_ext_lookup_ith(ext, i, len));
+ }
+ }
+
+ return(NULL);
+}