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author | Mark Purcell <msp@debian.org> | 2008-06-22 11:00:40 +1000 |
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committer | etobi <git@e-tobi.net> | 2013-09-03 09:48:42 +0200 |
commit | 891c51ff368ed700dec6025eeb47ce4d96f76418 (patch) | |
tree | 3729664829e4faa691d403274f38eb10890b533c /lib/libucsi/section.h | |
parent | 1c6e1f28f54ec2606c23936c1d8689f2be55a86c (diff) | |
parent | ab959d7b4194715870128e616b8e29d4a101e488 (diff) | |
download | linux-dvb-apps-debian/1.1.1+rev1207-1.tar.gz |
Imported Debian patch 1.1.1+rev1207-1debian/1.1.1+rev1207-1
Diffstat (limited to 'lib/libucsi/section.h')
-rw-r--r-- | lib/libucsi/section.h | 253 |
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 |