- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
I have two different versions of "IA-32 Intel Architecture Software Developer's Manual". In Table A-2 "One-byte Opcode Map", one says 0x82 is "Ev, Ib"(the same as 0x83)but the other says 0x82 is "Eb, Ib"(the same as 0x80). But in "instruction set reference", it seems 0x82 is never used(for example, instruction __add__). So, is 0x82 a valid opcode? If it is, how should I decode it?
Thanks
Message Edited by minwang on 10-21-2004 05:53 PM
Link Copied
5 Replies
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
Greetings fromIntel Software NetworkSupport.
Wewill check onthiswith our engineering team and let you know.
Regards,
Message Edited by intel.software.network.support on 11-30-2005 04:26 PM
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
Here is the response we received from our hardware engineering contacts:
0x82 is a valid instruction. It decodes to ADD, SUB, AND, OR, XOR depending on the MODRM. If MOD is 11 then we have memory operations. Group 1 (row 1) in table A-4 (appdx A) defines how the instruction is decoded from that point onwards. The ADD entry of table B-10 shows the decode for opcode 0x82.
Regards,
Lexi S.
IntelSoftware NetworkSupport
Message Edited by intel.software.network.support on 11-30-2005 04:26 PM
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
Is there any difference between opcode 0x82 and 0x83? From the "one-byte opcode map (table A-2)", it seems they're identicle.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
We asked for clarification from our engineering contacts, whohave indicated that you should go by the most recent release of the documentation. The MODRM byte details the instructions interpretation.
We hope this is helpful.
Regards,
Message Edited by intel.software.network.support on 11-30-2005 04:26 PM
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
Quoting - minwang
Is there any difference between opcode 0x82 and 0x83? From the "one-byte opcode map (table A-2)", it seems they're identicle.
Reply
Topic Options
- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page