Re: [Discuss-gnuradio] The effect of FUSB_BLOCK_SIZE and FUSB_NBLOCKS

[Stefan Brüns]

On Wednesday 04 March 2009 12:26:09 Stefan Bruens wrote:
> 0 means default. Excerpt from fusb_linux.cc:
> ---
> static const int MAX_BLOCK_SIZE = fusb_sysconfig::max_block_size();
> static const int DEFAULT_BLOCK_SIZE = MAX_BLOCK_SIZE;
> static const int DEFAULT_BUFFER_SIZE = 4 * (1L << 20);
> if (d_block_size == 0)
>   d_block_size = DEFAULT_BLOCK_SIZE;
> if (d_nblocks == 0)
>   d_nblocks = std::max (1, DEFAULT_BUFFER_SIZE / d_block_size);
> ---
> max_block_size() is 16kB

Just a small correction, usrp_basic.cc sets default values on its own, taken 
from fusb_sysconfig_linux.cc, so it ends up with:
default block size: 4kB
default buffer size: 1MB
number of blocks: 1MB/4kB => 256

so on Linux {0,0} is the same as {4096,256}. Values for OsX/Win/BSD might be 
different.

Stefan

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