1 files changed, 253 insertions, 0 deletions
diff --git a/lib/libucsi/section.h b/lib/libucsi/section.h
new file mode 100644
index 0000000..53ad07f
--- /dev/null
+++ b/lib/libucsi/section.h
@@ -0,0 +1,253 @@
+/*
+ * section and descriptor parser
+ *
+ * Copyright (C) 2005 Kenneth Aafloy (kenneth@linuxtv.org)
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+#ifndef _UCSI_SECTION_H
+#define _UCSI_SECTION_H 1
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+#include <libucsi/endianops.h>
+#include <libucsi/descriptor.h>
+#include <libucsi/crc32.h>
+#include <stdint.h>
+#include <string.h>
+
+#define CRC_SIZE 4
+
+
+/**
+ * Generic section header.
+ */
+struct section {
+	uint8_t	table_id;
+  EBIT4(uint16_t syntax_indicator	: 1; ,
+	uint16_t private_indicator	: 1; , /* 2.4.4.10 */
+	uint16_t reserved 		: 2; ,
+	uint16_t length			:12; );
+} __ucsi_packed;
+
+/**
+ * Generic extended section header structure.
+ */
+struct section_ext {
+	uint8_t	table_id;
+  EBIT4(uint16_t syntax_indicator	: 1; ,
+	uint16_t private_indicator	: 1; , /* 2.4.4.10 */
+	uint16_t reserved		: 2; ,
+	uint16_t length			:12; );
+
+	uint16_t table_id_ext;
+  EBIT3(uint8_t reserved1		: 2; ,
+	uint8_t version_number		: 5; ,
+	uint8_t current_next_indicator	: 1; );
+	uint8_t section_number;
+	uint8_t last_section_number;
+} __ucsi_packed;
+
+/**
+ * Structure for keeping track of sections of a PSI table.
+ */
+struct psi_table_state {
+	uint8_t version_number;
+	uint16_t next_section_number;
+	uint8_t complete:1;
+	uint8_t new_table:1;
+} __ucsi_packed;
+
+
+/**
+ * Determine the total length of a section, including the header.
+ *
+ * @param section The parsed section structure.
+ * @return The length.
+ */
+static inline size_t section_length(struct section *section)
+{
+	return section->length + sizeof(struct section);
+}
+
+/**
+ * Determine the total length of an extended section, including the header,
+ * but omitting the CRC.
+ *
+ * @param section The parsed section_ext structure.
+ * @return The length.
+ */
+static inline size_t section_ext_length(struct section_ext * section)
+{
+	return section->length + sizeof(struct section) - CRC_SIZE;
+}
+
+/**
+ * Process a section structure in-place.
+ *
+ * @param buf Pointer to the data.
+ * @param len Length of data.
+ * @return Pointer to the section structure, or NULL if invalid.
+ */
+static inline struct section * section_codec(uint8_t * buf, size_t len)
+{
+	struct section * ret = (struct section *)buf;
+
+	if (len < 3)
+		return NULL;
+
+	bswap16(buf+1);
+
+	if (len != ret->length + 3U)
+		return NULL;
+
+	return ret;
+}
+
+/**
+ * Some sections have a CRC even though they are not section_exts.
+ * This function is to allow checking of them.
+ *
+ * @param section Pointer to the processed section structure.
+ * @return Nonzero on error, or 0 if the CRC was correct.
+ */
+static inline int section_check_crc(struct section *section)
+{
+	uint8_t * buf = (uint8_t *) section;
+	size_t len = section_length(section);
+	uint32_t crc;
+
+	/* the crc check has to be performed on the unswapped data */
+	bswap16(buf+1);
+	crc = crc32(CRC32_INIT, buf, len);
+	bswap16(buf+1);
+
+	/* the crc check includes the crc value,
+	 * the result should therefore be zero.
+	 */
+	if (crc)
+		return -1;
+	return 0;
+}
+
+
+/**
+ * Decode an extended section structure.
+ *
+ * @param section Pointer to the processed section structure.
+ * @param check_crc If 1, the CRC of the section will also be checked.
+ * @return Pointer to the parsed section_ext structure, or NULL if invalid.
+ */
+static inline struct section_ext * section_ext_decode(struct section * section,
+						      int check_crc)
+{
+	if (section->syntax_indicator == 0)
+		return NULL;
+
+	if (check_crc) {
+		if (section_check_crc(section))
+			return NULL;
+	}
+
+	bswap16((uint8_t *)section + sizeof(struct section));
+
+	return (struct section_ext *)section;
+}
+
+/**
+ * Encode an extended section structure for transmission.
+ *
+ * @param section Pointer to the section_ext structure.
+ * @param update_crc If 1, the CRC of the section will also be updated.
+ * @return Pointer to the encoded section_ext structure, or NULL if invalid.
+ */
+static inline struct section_ext * section_ext_encode(struct section_ext* section,
+						      int update_crc)
+{
+	if (section->syntax_indicator == 0)
+		return NULL;
+
+	bswap16((uint8_t *)section + sizeof(struct section));
+
+	if (update_crc) {
+		uint8_t * buf = (uint8_t *) section;
+		int len = sizeof(struct section) + section->length;
+		uint32_t crc;
+
+		/* the crc has to be performed on the swapped data */
+		bswap16(buf+1);
+		crc = crc32(CRC32_INIT, buf, len-4);
+		bswap16(buf+1);
+
+		/* update the CRC */
+		*((uint32_t*) (buf+len-4)) = crc;
+		bswap32(buf+len-4);
+	}
+
+	return (struct section_ext *)section;
+}
+
+/**
+ * Reset a psi_table_state structure.
+ *
+ * @param tstate The structure to reset.
+ */
+static inline void psi_table_state_reset(struct psi_table_state *tstate)
+{
+	tstate->version_number = 0xff;
+}
+
+/**
+ * Check if a supplied section_ext is something we want to process.
+ *
+ * @param section The parsed section_ext structure.
+ * @param tstate The state structure for this PSI table.
+ * @return 0=> not useful. nonzero => useful.
+ */
+static inline int section_ext_useful(struct section_ext *section, struct psi_table_state *tstate)
+{
+	if ((section->version_number == tstate->version_number) && tstate->complete)
+		return 0;
+	if (section->version_number != tstate->version_number) {
+	        if (section->section_number != 0)
+	                return 0;
+
+		tstate->next_section_number = 0;
+		tstate->complete = 0;
+		tstate->version_number = section->version_number;
+		tstate->new_table = 1;
+	} else if (section->section_number == tstate->next_section_number) {
+		tstate->new_table = 0;
+	} else {
+		return 0;
+	}
+
+	tstate->next_section_number++;
+	if (section->last_section_number < tstate->next_section_number) {
+		tstate->complete = 1;
+	}
+
+	return 1;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif