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Octavio

Joined: 21 Jun 2003
Posts: 366
Location: Spain

Octavio 18 Apr 2005, 16:10

amd 3dnow instructions like

pavgusb mm1,mm2 ;db 0fh,0fh,0cah,0bfh

are encoded with the modrm byte (0cah) before the opcode byte (0bfh)
i haven´t tested if this works but usually opcode byte is before modrm.
I have assembled it with fasm1.46 and fasm1.59

18 Apr 2005, 16:10

f0dder

Joined: 19 Feb 2004
Posts: 3175
Location: Denmark

f0dder 18 Apr 2005, 16:28

mikael "fluff" klasson's hexit assembles it as 0f0fcabf, too...

18 Apr 2005, 16:28

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8351
Location: Kraków, Poland

Tomasz Grysztar 18 Apr 2005, 22:57

The third opcode byte for AMD 3DNow! is really an immediate byte for the instruction 0Fh-0Fh, and therefore comes last.

18 Apr 2005, 22:57

Octavio

Joined: 21 Jun 2003
Posts: 366
Location: Spain

Octavio 18 Apr 2005, 23:56

Privalov wrote:

The third opcode byte for AMD 3DNow! is really an immediate byte for the instruction 0Fh-0Fh, and therefore comes last.

thanks for the explanations ,the amd docs i have are really a data shit Evil or Very Mad

Please can someone tellme where to download the latest instructions sets for intel and amd.

18 Apr 2005, 23:56

MazeGen

Joined: 06 Oct 2003
Posts: 977
Location: Czechoslovakia

MazeGen 19 Apr 2005, 07:59

http://developer.intel.com/design/Pentium4/documentation.htm#manuals

http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_739_7044,00.html

19 Apr 2005, 07:59

Octavio

Joined: 21 Jun 2003
Posts: 366
Location: Spain

Octavio 19 Apr 2005, 16:27

Thanks

19 Apr 2005, 16:27

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