% PT_INSN_ALLOC_DECODER(3)

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# 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)