% PT_INSN_ALLOC_DECODER(3)

<!---
 ! Copyright (c) 2015-2016, Intel Corporation
 !
 ! Redistribution and use in source and binary forms, with or without
 ! modification, are permitted provided that the following conditions are met:
 !
 !  * Redistributions of source code must retain the above copyright notice,
 !    this list of conditions and the following disclaimer.
 !  * Redistributions in binary form must reproduce the above copyright notice,
 !    this list of conditions and the following disclaimer in the documentation
 !    and/or other materials provided with the distribution.
 !  * Neither the name of Intel Corporation nor the names of its contributors
 !    may be used to endorse or promote products derived from this software
 !    without specific prior written permission.
 !
 ! THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 ! AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 ! IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 ! ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 ! LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 ! CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 ! SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 ! INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 ! CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 ! ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 ! POSSIBILITY OF SUCH DAMAGE.
 !-->

# NAME

pt_insn_alloc_decoder, pt_insn_free_decoder - allocate/free an Intel(R)
Processor Trace instruction flow decoder


# SYNOPSIS

| **\#include `<intel-pt.h>`**
|
| **struct pt_insn_decoder \***
| **pt_insn_alloc_decoder(const struct pt_config \**config*);**
|
| **void pt_insn_free_decoder(struct pt_insn_decoder \**decoder*);**

Link with *-lipt*.


# DESCRIPTION

An instruction flow decoder decodes raw Intel Processor Trace (Intel PT) into a
sequence of instructions described by the *pt_insn* structure.  See
**pt_insn_next**(3).

**pt_insn_alloc_decoder**() allocates a new instruction flow 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 instruction flow decoder needs to be synchronized onto the trace
stream before it can be used.  To synchronize the instruction flow decoder, use
**pt_insn_sync_forward**(3), **pt_insn_sync_backward**(3), or
**pt_insn_sync_set**(3).

**pt_insn_free_decoder**() frees the Intel PT instruction flow 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_insn_alloc_decoder**().


# RETURN VALUE

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


# EXAMPLE

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

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

	errcode = bar(decoder);

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


# SEE ALSO

**pt_config**(3), **pt_insn_sync_forward**(3), **pt_insn_sync_backward**(3),
**pt_insn_sync_set**(3), **pt_insn_get_offset**(3), **pt_insn_get_sync_offset**(3),
**pt_insn_get_image**(3), **pt_insn_set_image**(3), **pt_insn_get_config**(3),
**pt_insn_time**(3), **pt_insn_core_bus_ratio**(3), **pt_insn_next**(3)
