clipka wrote:
> Thorsten Froehlich <tho### [at] trfde> wrote:
>> clipka wrote:
>>> Don't expect all these to be "naive hardware implementation" in the same sense
>>> as, say, an integer addition, shift, bit-wise AND/OR/XOR or whatever.
>> Exactly that is why you ought to be looking at the SSE2/3 floating-point
>> registers and associated hardware support. The x87 FPU is only there for
>> legacy support and rather inefficient.
> 
> Hah! Say that again...
> 


> SSE3, SSSE3 to SSE4 is rather primitive compared to what the x87 FPU can do -
> except when it comes to bulk add, subtract, multiply or divide. Which is what
> they're designed for: Vectors and matrices. That's why they're called Streaming
> SIMD (= Single Instruction Multiple Data) Extensions.
> 
> Search for trigonometric or logarithmic functions - you'll not find any in the
> SSE2 or SSE3 sections. You'll probably find that these still rely on good old
> x87 FPU instructions.

You are looking at the wrong manual. This manual does not tell you how to do 
something but what is available.  I admit the Intel documentation is not 
clear, but x87 usage is deprecated. This is documented for x86-64 mode in OS 
vendor information because the x86-64 ABIs even use the SSE registers for 
argument passing (no more x87 FPU stack or memory mapped argument passing). 
But googling for that information is difficult. One of the top-most useful 
links I found was 
<http://msdn.microsoft.com/en-us/library/bb147385.aspx#ID0EBEAA> - you will 
have to look up the remaining information yourself. I guess AMD might have 
more info, as they came up with x86-64.....

	Thorsten

Post a reply to this message