[time-nuts] An embedded NTP server

Jim Lux jimlux at earthlink.net
Wed Jan 2 23:36:25 UTC 2013


On 1/2/13 11:37 AM, Poul-Henning Kamp wrote:
>
> Actually, the OS is not important, floating point support is.
>


floating point support in the sense that the compiler supports it and 
generates appropriate code to use software FP or hardware FP as available?

Or you need HW floating point for performance.
(after all, I ran floating point FORTRAN code on a 4 MHz Z80 with 48k 
back in the late 70s... not speedy, but it works)

We just went through an exercise to enable the use of HW FP on our SPARC 
processors for flight use.  The original gcc tool chain & RTEMS setup 
used software FP, even though the hardware has an FPU.  But to implement 
the GPS receiver, we needed HW FP, so we had to work through all those 
issues.  I don't recall precisely what the issues were (probably 
something about saving/restoring FPU registers or, at least, not 
tampering with their contents through an interrupt or library call).

The problem wasn't that GCC couldn't generate the right object code, it 
was something more high level than that.



>




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