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diff --git a/libipt/internal/include/pt_tnt_cache.h b/libipt/internal/include/pt_tnt_cache.h
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+++ b/libipt/internal/include/pt_tnt_cache.h
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+/*
+ * Copyright (c) 2013-2019, Intel Corporation
+ *
+ * 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 Intel Corporation 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 OWNER 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.
+ */
+
+#ifndef PT_TNT_CACHE_H
+#define PT_TNT_CACHE_H
+
+#include <stdint.h>
+
+struct pt_packet_tnt;
+struct pt_config;
+
+
+/* Keeping track of tnt indicators. */
+struct pt_tnt_cache {
+	/* The last tnt. */
+	uint64_t tnt;
+
+	/* The index into the above tnt.
+	 *
+	 * (tnt & index) gives the current tnt entry.
+	 * (index >>= 1) moves the index to the next tnt entry.
+	 * (index == 0) means that the current tnt is empty.
+	 */
+	uint64_t index;
+};
+
+
+/* Initialize (or reset) the tnt cache. */
+extern void pt_tnt_cache_init(struct pt_tnt_cache *cache);
+
+/* Check if the tnt cache is empty.
+ *
+ * Returns 0 if the tnt cache is not empty.
+ * Returns > 0 if the tnt cache is empty.
+ * Returns -pte_invalid if @cache is NULL.
+ */
+extern int pt_tnt_cache_is_empty(const struct pt_tnt_cache *cache);
+
+/* Query the next tnt indicator.
+ *
+ * This consumes the returned tnt indicator in the cache.
+ *
+ * Returns 0 if the next branch is not taken.
+ * Returns > 0 if the next branch is taken.
+ * Returns -pte_invalid if @cache is NULL.
+ * Returns -pte_bad_query if there is no tnt cached.
+ */
+extern int pt_tnt_cache_query(struct pt_tnt_cache *cache);
+
+/* Update the tnt cache based on Intel PT packets.
+ *
+ * Updates @cache based on @packet and, if non-null, @config.
+ *
+ * Returns zero on success.
+ * Returns -pte_invalid if @cache or @packet is NULL.
+ * Returns -pte_bad_packet if @packet appears to be corrupted.
+ * Returns -pte_bad_context if the tnt cache is not empty.
+ */
+extern int pt_tnt_cache_update_tnt(struct pt_tnt_cache *cache,
+				   const struct pt_packet_tnt *packet,
+				   const struct pt_config *config);
+
+#endif /* PT_TNT_CACHE_H */