From: Stephen Hemminger <[EMAIL PROTECTED]>
Date: Mon, 12 Dec 2005 12:03:22 -0800
> - d32 = d32 / HZ;
> -
> /* (wmax-cwnd) * (srtt>>3 / HZ) / c * 2^(3*bictcp_HZ) */
> - d64 = (d64 * dist * d32) >> (count+3-BICTCP_HZ);
> -
> - /* cubic root */
> - d64 = cubic_root(d64);
> -
> - result = (u32)d64;
> - return result;
> + return cubic_root((cube_factor * dist) >> (cube_scale + 3 - BICTCP_HZ));
...
> + while ( !(d32 & 0x80000000) && (cube_scale < BICTCP_HZ)){
> + d32 = d32 << 1;
> + ++cube_scale;
> + }
> + cube_factor = d64 * d32 / HZ;
> +
I don't think this transformation is equivalent.
In the old code only the "d32" is scaled by HZ.
So in the old code we're saying something like:
d64 = (d64 * dist * (d32 / HZ)) >> (count + 3 - BICTCP_HZ);
whereas the new code looks like:
d64 = (((d64 * d32) / HZ) * dist) >> (count + 3 - BICTCP_HZ);
Is that really equivalent?
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