% PT_INSN_ALLOC_DECODER(3)
# 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)