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Mail Archives: djgpp/1994/10/06/06:42:10

Date: Thu, 6 Oct 1994 10:14:17 +0100
From: terra AT diku DOT dk
To: FIXER AT FAXCSL DOT DCRT DOT NIH DOT GOV
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Re: 16/32 (was: djgpp and the 386SX)

   Date: Wed, 5 Oct 1994 18:38:59 -0400 (EDT)
   From: Chris Tate <FIXER AT FAXCSL DOT DCRT DOT NIH DOT GOV>

[...]

   I believe that 16-bit integer operations are faster on the I486 and before;
   I don't know about the Pentium.  Anybody know for sure?

(meaning faster than 32-bit operations)

There is no execution time difference between 16-bit operations and
32-bit operations for i[34]86.

However, if you are in a 32-bit segment (djgpp world) then 16-bit
operation have to be tagged with a prefix which make them slower.
In a 16-bit segment (dos world) it is the other way round.

Furthermore, the execution times for multiplication and division
depend and the actual values used, but not on the size of the
registers used.

Morten

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