Re! XCHG instruction: load register AX with a 1

From: "Wilco Dijkstra" <Wilco_dot_Dijkstra@xxxxxxxxxxxx>
Date: Tue, 28 Nov 2006 22:24:42 GMT

"2005" <uws2003@xxxxxxxxx> wrote in message
news:1164745288.708611.241670@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Hi

In the XCHG instruction, why would be load register AX with a 1 prior
to excution of XCHG - is this
- to insure that the "Flag" variable will be set to 1 after the XCHG or
- the XCHG instruction will not work unless a 1 is loaded into AX
before executing the XCHG instruction ?

Don't listen to the other guys, they are trying to trick you. You should
load EAX with 0x01010101, then the flag will be correctly set to 1
irrespectively of the endian setting.

Wilco

.

References:
- XCHG instruction: load register AX with a 1
  - From: 2005

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