% PT_BLK_ALLOC_DECODER(3)

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# NAME

pt_blk_alloc_decoder, pt_blk_free_decoder - allocate/free an Intel(R) Processor

Trace block decoder

# SYNOPSIS

| **\#include `<intel-pt.h>`**

|

| **struct pt_block_decoder \***

| **pt_blk_alloc_decoder(const struct pt_config \**config*);**

|

| **void pt_blk_free_decoder(struct pt_block_decoder \**decoder*);**

Link with *-lipt*.

# DESCRIPTION

A block decoder decodes raw Intel Processor Trace (Intel PT) into a sequence of

blocks of instructions described by the *pt_block* structure.  See

**pt_blk_next**(3).

**pt_blk_alloc_decoder**() allocates a new block decoder and returns a pointer

to it.  The *config* argument points to a *pt_config* object.  See

**pt_config**(3).  The *config* argument will not be referenced by the returned

decoder but the trace buffer defined by the *config* argument's *begin* and

*end* fields will.

The returned block decoder needs to be synchronized onto the trace stream before

it can be used.  To synchronize the decoder, use **pt_blk_sync_forward**(3),

**pt_blk_sync_backward**(3), or **pt_blk_sync_set**(3).

**pt_blk_free_decoder**() frees the Intel PT block decoder pointed to by

*decoder*.  The *decoder* argument must be NULL or point to a decoder that has

been allocated by a call to **pt_blk_alloc_decoder**().

# RETURN VALUE

**pt_blk_alloc_decoder**() returns a pointer to a *pt_block_decoder* object on

success or NULL in case of an error.

# EXAMPLE

~~~{.c}

    struct pt_block_decoder *decoder;

    int errcode;

    decoder = pt_blk_alloc_decoder(config);

    if (!decoder)

        return pte_nomem;

    errcode = decode(decoder);

    pt_blk_free_decoder(decoder);

    return errcode;

~~~

# SEE ALSO

**pt_config**(3), **pt_blk_sync_forward**(3), **pt_blk_sync_backward**(3),

**pt_blk_sync_set**(3), **pt_blk_get_offset**(3), **pt_blk_get_sync_offset**(3),

**pt_blk_get_image**(3), **pt_blk_set_image**(3), **pt_blk_get_config**(3),

**pt_blk_time**(3), **pt_blk_core_bus_ratio**(3), **pt_blk_next**(3)