Q31598: Sign-Extended Register and Immediate Form of AND/OR/XOR
Article: Q31598
Product(s): Microsoft Macro Assembler
Version(s): 5.0,5.1,6.0
Operating System(s):
Keyword(s):
Last Modified: 06-MAY-2001
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The information in this article applies to:
- Microsoft Macro Assembler (MASM), versions 5.0, 5.1, 6.0
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SUMMARY
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The Microsoft Macro Assembler will generate sign-extended encodings whenever
possible. The following are MASM instructions that will produce sign-extended
encodings:
Assembler Sign-Extended Nonsign-Extended
Instructions Encodings Encodings
AND bx, 0ffffh 83 E3 FF 81 E3 FFFF
ADD bx, 0001h 83 C3 01 81 C3 0001
ADC bx, 0fh 83 D3 0F 81 D3 000F
OR bx, 1 83 CB 01 81 CB 0001
SBB bx, 0ffffh 83 DB FF 81 DB FFFF
SUB bx, 3 83 EB 03 81 EB 0003
XOR bx, 0002h 83 F3 02 81 F3 0002
CMP bx, 0fff2h 83 FB F2 81 FB FFF2
MORE INFORMATION
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MASM will choose the sign-extended version of the instruction because of the
1-byte savings in the encoding. The 8088/8086/80186/80286 processors do support
the sign-extended encoding, but documentation on this feature is limited. The
support of sign-extended encoding is documented in the "8086/8088/80186/80188
Programmer's Pocket Reference Guide" on Page 43.
Additional query words: kbinf 5.00 5.10 6.00
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Keywords :
Technology : kbMASMsearch kbAudDeveloper kbMASM510 kbMASM600 kbMASM500
Version : :5.0,5.1,6.0
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