% PT_PKT_ALLOC_DECODER(3)

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# NAME

pt_pkt_alloc_decoder, pt_pkt_free_decoder - allocate/free an Intel(R) Processor
Trace packet decoder


# SYNOPSIS

| **\#include `<intel-pt.h>`**
|
| **struct pt_packet_decoder \***
| **pt_pkt_alloc_decoder(const struct pt_config \**config*);**
|
| **void pt_pkt_free_decoder(struct pt_packet_decoder \**decoder*);**

Link with *-lipt*.


# DESCRIPTION

**pt_pkt_alloc_decoder**() allocates a new Intel Processor Trace (Intel PT)
packet decoder and returns a pointer to it.  The packet decoder decodes raw
Intel PT trace into a stream of *pt_packet* objects.  See **pt_pkt_next**(3).

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 packet decoder needs to be synchronized onto the trace stream
before it can be used.  To synchronize the packet decoder, use
**pt_pkt_sync_forward**(3), **pt_pkt_sync_backward**(3), or
**pt_pkt_sync_set**(3).

**pt_pkt_free_decoder**() frees the Intel PT packet 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_pkt_alloc_decoder**().


# RETURN VALUE

**pt_pkt_alloc_decoder**() returns a pointer to a *pt_packet_decoder* object on
success or NULL in case of an error.


# EXAMPLE

~~~{.c}
int foo(const struct pt_config *config) {
	struct pt_packet_decoder *decoder;
	errcode;

	decoder = pt_pkt_alloc_decoder(config);
	if (!decoder)
		return pte_nomem;

	errcode = bar(decoder);

	pt_pkt_free_decoder(decoder);
	return errcode;
}
~~~


# SEE ALSO

**pt_config**(3), **pt_pkt_sync_forward**(3), **pt_pkt_sync_backward**(3),
**pt_pkt_sync_set**(3), **pt_pkt_get_offset**(3), **pt_pkt_get_sync_offset**(3),
**pt_pkt_get_config**(3), **pt_pkt_next**(3)