[fpc-devel] Extended in Win64

Daniël Mantione daniel.mantione at freepascal.org
Tue May 6 15:51:16 CEST 2008

Op Tue, 6 May 2008, schreef Jonas Maebe:

> On 06 May 2008, at 15:02, petr.kristan at epos.cz wrote:
>> Why on Win64 on AMD64 is Extended type 64bit same as double and on Win32, 
>> Linux32 and
>> Linux64 is 80bit.
> Because the original win64 releases did not support the use of the 80x87 
> floating point unit

Actually this is a myth, originating from Microsoft itself. Win64 has 
always supported the x87, but early Microsoft documentation said
it did not. This confused Microsofts' MASM coders which disabled the x87 
instructions in MASM.


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