Messages in this thread |  | | From | Albert Cahalan <> | Subject | 64-bit math in the kernel | Date | Thu, 14 Nov 1996 19:27:10 -0500 (EST) |
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What is the best way to divide a __u64 by a __u32 in the kernel? The result will fit in a __u32.
It seems gcc requires libgcc to do that, but libgcc is not available. Right now the code casts to a double, but it is not good to use the FPU in the kernel. I do have a disgusting hack that does the job in 4 divisions and 3 multiplications (hmmm, is div() available?), but the hack takes almost 4 times as long on a Pentium.
Just how bad are FPU operations in the kernel? I seem to remember that the FPU memcpy patch had to take special precautions to avoid corrupting data.
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