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libdvbpsi/0001-dvbpsi_decoder_t-solve...

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From 61b43151b3ee99ebba38b038e9e92d34766cf897 Mon Sep 17 00:00:00 2001
From: Jean-Paul Saman <jpsaman@videolan.org>
Date: Tue, 16 Oct 2012 10:56:26 +0200
Subject: [PATCH 1/2] dvbpsi_decoder_t: solve alignment issues with
dvbpsi_decoder_t casting.
Repack DVBPSI_DECODER_COMMON to be byte aligned and add some checks to
do clever casting.
The TOT and SIS table structure definition need to be packed explicitly for use on ARM and MIPS platforms.
---
src/dvbpsi.c | 3 +-
src/dvbpsi.h | 82 +++++++++++++++++++++++++++++++++++-------------
src/tables/nit_private.h | 4 +--
src/tables/pmt_private.h | 4 +--
src/tables/sis.h | 2 +-
src/tables/tot.h | 2 +-
6 files changed, 68 insertions(+), 29 deletions(-)
diff --git a/src/dvbpsi.c b/src/dvbpsi.c
index ffbfaca..d45802e 100644
--- a/src/dvbpsi.c
+++ b/src/dvbpsi.c
@@ -170,7 +170,7 @@ void dvbpsi_delete(dvbpsi_t *p_dvbpsi)
* dvbpsi_decoder_new
*****************************************************************************/
#define DVBPSI_INVALID_CC (0xFF)
-dvbpsi_decoder_t *dvbpsi_decoder_new(dvbpsi_callback_gather_t pf_gather,
+void *dvbpsi_decoder_new(dvbpsi_callback_gather_t pf_gather,
const int i_section_max_size, const bool b_discontinuity, const size_t psi_size)
{
assert(psi_size >= sizeof(dvbpsi_decoder_t));
@@ -179,6 +179,7 @@ dvbpsi_decoder_t *dvbpsi_decoder_new(dvbpsi_callback_gather_t pf_gather,
if (p_decoder == NULL)
return NULL;
+ memcpy(&p_decoder->i_magic[0], "psi", 3);
p_decoder->pf_gather = pf_gather;
p_decoder->p_current_section = NULL;
p_decoder->i_section_max_size = i_section_max_size;
diff --git a/src/dvbpsi.h b/src/dvbpsi.h
index 3118da8..8a019e3 100644
--- a/src/dvbpsi.h
+++ b/src/dvbpsi.h
@@ -43,6 +43,16 @@ extern "C" {
#endif
/*****************************************************************************
+ * Helper for GCC version checks borrowed from VLC.
+ *****************************************************************************/
+#ifdef __GNUC__
+# define DVBPSI_GCC_VERSION(maj,min) \
+ ((__GNUC__ > (maj)) || (__GNUC__ == (maj) && __GNUC_MINOR__ >= (min)))
+#else
+# define DVBPSI_GCC_VERSION(maj,min) (0)
+#endif
+
+/*****************************************************************************
* dvbpsi_t
*****************************************************************************/
/*!
@@ -90,7 +100,22 @@ typedef struct dvbpsi_decoder_s dvbpsi_decoder_t;
* \def DVBPSI_DECODER(x)
* \brief Helper macro for casting a private decoder into a dvbpsi_decoder_t
*/
-#define DVBPSI_DECODER(x) ((dvbpsi_decoder_t *)(x))
+/* Clever cast borrowed from VLC */
+#if DVBPSI_GCC_VERSION(4,0)
+# ifndef __cplusplus
+# define DVBPSI_DECODER( x ) \
+ __builtin_choose_expr( \
+ __builtin_offsetof(__typeof__(*(x)), i_magic), \
+ (void)0, \
+ (dvbpsi_decoder_t *)(x))
+# else
+# define DVBPSI_DECODER( x ) \
+ ((dvbpsi_decoder_t *)(x) \
+ + 0 * __builtin_offsetof(__typeof__(*(x)), i_magic))
+# endif
+#else
+# define DVBPSI_DECODER(x) ((dvbpsi_decoder_t *)(x))
+#endif
/*****************************************************************************
* dvbpsi_t
@@ -187,6 +212,28 @@ typedef void (* dvbpsi_callback_gather_t)(dvbpsi_t *p_dvbpsi, /*!< pointer to d
dvbpsi_psi_section_t* p_section); /*!< pointer to psi section */
/*****************************************************************************
+ * DVBPSI_DECODER_COMMON
+ *****************************************************************************/
+#define DVBPSI_DECODER_COMMON \
+/*! \
+ * \name DVBPSI_DECODER_COMMON \
+ * these members are common for all dvbpsi_decoder_t \
+ */ \
+/**@{*/ \
+ uint8_t i_magic[3]; /*!< Reserved magic value */ \
+ bool b_complete_header; /*!< Flag for header completion */ \
+ bool b_discontinuity; /*!< Discontinuity flag */ \
+ bool b_current_valid; /*!< Current valid indicator */ \
+ uint8_t i_continuity_counter; /*!< Continuity counter */ \
+ uint8_t i_last_section_number;/*!< Last received section number */ \
+ dvbpsi_psi_section_t *p_current_section; /*!< Current section */ \
+ dvbpsi_psi_section_t *p_sections; /*!< List of received PSI sections */ \
+ dvbpsi_callback_gather_t pf_gather;/*!< PSI decoder's callback */ \
+ int i_section_max_size; /*!< Max size of a section for this decoder */ \
+ int i_need; /*!< Bytes needed */ \
+/**@}*/
+
+/*****************************************************************************
* struct dvbpsi_decoder_s
*****************************************************************************/
/*!
@@ -196,18 +243,6 @@ typedef void (* dvbpsi_callback_gather_t)(dvbpsi_t *p_dvbpsi, /*!< pointer to d
* This structure shouldn't be used but if you want to write an external
* decoder.
*/
-#define DVBPSI_DECODER_COMMON \
- dvbpsi_callback_gather_t pf_gather;/*!< PSI decoder's callback */ \
- int i_section_max_size; /*!< Max size of a section for this decoder */ \
- uint8_t i_continuity_counter; /*!< Continuity counter */ \
- bool b_discontinuity; /*!< Discontinuity flag */ \
- dvbpsi_psi_section_t *p_current_section; /*!< Current section */ \
- bool b_current_valid; /*!< Current valid indicator */ \
- uint8_t i_last_section_number;/*!< Last received section number */ \
- dvbpsi_psi_section_t *p_sections; /*!< List of received PSI sections */ \
- int i_need; /*!< Bytes needed */ \
- bool b_complete_header; /*!< Flag for header completion */
-
struct dvbpsi_decoder_s
{
DVBPSI_DECODER_COMMON
@@ -217,22 +252,25 @@ struct dvbpsi_decoder_s
* dvbpsi_decoder_new
*****************************************************************************/
/*!
- * \fn dvbpsi_decoder_t *dvbpsi_decoder_new(dvbpsi_callback_gather_t pf_gather,
+ * \fn void *dvbpsi_decoder_new(dvbpsi_callback_gather_t pf_gather,
* const int i_section_max_size, const bool b_discontinuity, const size_t psi_size);
- * \brief Create a new dvbpsi_decoder_t.
+ * \brief Create a new (private) dvbpsi decoder.
* \param pf_gather pointer to gather function for PSI decoder.
* \param i_section_max_size Max size of a section for this decoder
* \param b_discontinuity Discontinuity flag
* \param psi_size size of new PSI struct, eg: sizeof(dvbpsi_pat_t)
- * \return pointer to dvbpsi_decoder_t
+ * \return pointer to memory of size 'psi_size' that can be casted into a dvbpsi_decoder_t.
*
- * Creates a dvbpsi_decoder_t pointer to struct dvbpsi_decoder_s. It should be
- * delete with @see dvbpsi_decoder_delete() function.
+ * Creates a void pointer that points to a private dvbpsi decoder struct (eg: dvbpsi_pat_t).
+ * The first elements in this newly created decoder should contain DVBPSI_DECODER_COMMON, which
+ * corresponds to a dvbpsi_decoder_t.
+ * Upon return the pointer should be casted to the correct type. Delete the pointer
+ * with @see dvbpsi_decoder_delete() function.
*/
-dvbpsi_decoder_t *dvbpsi_decoder_new(dvbpsi_callback_gather_t pf_gather,
- const int i_section_max_size,
- const bool b_discontinuity,
- const size_t psi_size);
+void *dvbpsi_decoder_new(dvbpsi_callback_gather_t pf_gather,
+ const int i_section_max_size,
+ const bool b_discontinuity,
+ const size_t psi_size);
/*****************************************************************************
* dvbpsi_decoder_delete
diff --git a/src/tables/nit_private.h b/src/tables/nit_private.h
index 8eadce7..6c80e35 100644
--- a/src/tables/nit_private.h
+++ b/src/tables/nit_private.h
@@ -39,14 +39,14 @@ typedef struct dvbpsi_nit_decoder_s
{
DVBPSI_DECODER_COMMON
- uint16_t i_network_id;
-
dvbpsi_nit_callback pf_nit_callback;
void * p_cb_data;
dvbpsi_nit_t current_nit;
dvbpsi_nit_t * p_building_nit;
+ uint16_t i_network_id;
+
} dvbpsi_nit_decoder_t;
/*****************************************************************************
diff --git a/src/tables/pmt_private.h b/src/tables/pmt_private.h
index ed75a8b..4f10ecc 100644
--- a/src/tables/pmt_private.h
+++ b/src/tables/pmt_private.h
@@ -37,14 +37,14 @@ typedef struct dvbpsi_pmt_decoder_s
{
DVBPSI_DECODER_COMMON
- uint16_t i_program_number;
-
dvbpsi_pmt_callback pf_pmt_callback;
void * p_cb_data;
dvbpsi_pmt_t current_pmt;
dvbpsi_pmt_t * p_building_pmt;
+ uint16_t i_program_number;
+
} dvbpsi_pmt_decoder_t;
/*****************************************************************************
diff --git a/src/tables/sis.h b/src/tables/sis.h
index 16f2298..a339a6c 100644
--- a/src/tables/sis.h
+++ b/src/tables/sis.h
@@ -97,7 +97,7 @@ typedef struct dvbpsi_sis_s
/* FIXME: alignment stuffing */
uint32_t i_ecrc; /*!< CRC 32 of decrypted splice_info_section */
-} dvbpsi_sis_t;
+} __attribute__((packed)) dvbpsi_sis_t;
/*****************************************************************************
* Splice Commands
diff --git a/src/tables/tot.h b/src/tables/tot.h
index bb2a760..6ccf009 100644
--- a/src/tables/tot.h
+++ b/src/tables/tot.h
@@ -67,7 +67,7 @@ typedef struct dvbpsi_tot_s
uint32_t i_crc; /*!< CRC_32 (TOT only) */
-} dvbpsi_tot_t;
+} __attribute__((packed)) dvbpsi_tot_t;
/*****************************************************************************
* dvbpsi_tot_callback
--
1.7.11.7
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