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Re: [Discuss-gnuradio] Avoid double memory initilization in PMT unified
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] Avoid double memory initilization in PMT unified vectors |
Date: |
Tue, 7 Oct 2008 12:23:28 -0700 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Tue, Oct 07, 2008 at 07:26:08PM +0200, Stefan Brüns wrote:
> Hi,
>
> in PMT, there is code like:
>
> pmt_u8vector::pmt_u8vector(size_t k, uint8_t fill)
> : d_v(k)
> {
> for (size_t i = 0; i < k; i++)
> d_v[i] = fill;
> }
>
> As std::vector initializes the memory by itself when called with an size
> argument in the constructor, the memory is initialized twice.
>
> A faster version with the same result is:
>
> pmt_u8vector::pmt_u8vector(size_t k, uint8_t fill)
> : d_v(k, fill)
> {}
Thanks. I'll fix.
> Same is true for the other data types.
>
> Another question:
> Why are the classes for the different types written "by hand", and not using
> templates, eg:
>
> template <typename T>
> class pmt_uniform_vector
> {
> ...
> }
> typedef pmt_uniform_vector< uint8_t > pmt_u8vector;
>
> Stefan
My goal was to keep the interface completely opaque. It's likely that
the underlying implementation will be completely rewritten at some
point. Although we're currently using a C++ style implementation,
it's quite possible that we'll move to a more lisp-style
implementation with type info stored in the low pointer bits, GC
instead of reference counting, etc.
Using templates in the .cc files to reduce replicated code would be a
good idea with the current implementation.
Eric