Article: Q79835
Product(s): Microsoft Macro Assembler
Version(s): 6.0,6.0a,6.0b,6.10,6.10a
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 6.0, 6.0a, 6.0b, 6.10, 6.10a
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SYMPTOMS
========
When using the Microsoft Macro Assembler (MASM) to generate a listing file for
an assembler source file that contains a CMPXCHG instruction, errors may occur
in that listing. A colon is appended to bytes of values 26h, 2Eh, 36h, and 3Eh
when they appear in an instruction. For example, the following are generated:
0000 0F B0 26: 00 00 cmpxchg data1, ah
0005 0F B0 2E: 00 00 cmpxchg data1, ch
000A 0F B0 36: 00 00 cmpxchg data1, dh
000F 0F B0 3E: 00 00 cmpxchg data1, bh
instead of the following:
0000 0F B0 26 0000 R cmpxchg data1, ah
0005 0F B0 2E 0000 R cmpxchg data1, ch
000A 0F B0 36 0000 R cmpxchg data1, dh
000F 0F B0 3E 0000 R cmpxchg data1, bh
In addition, the address of a memory location is not always shown; instead, a
series of disjoint zero bytes appear. For example, the following is generated:
0014 0F B0 16 00 00 cmpxchg data2, dl
instead of the following:
0014 0F B0 16 0100 R cmpxchg data2, dl
Note that this also occurs in the first example. Finally, extra trailing bytes
may be placed in the listing file. For example, the following is generated:
0019 67& 0F B1 94 73 00000200 R cmpxchg data3[ebx+2*esi],dx
00 00 00 09
instead of the following:
0019 67& 0F B1 94 73 00000200 R cmpxchg data3[ebx+2*esi],dx
STATUS
======
Microsoft has confirmed this to be a problem in MASM versions 6.0, 6.0a, 6.0b,
6.1, and 6.1a. This problem was corrected in MASM for MS-DOS version 6.11.
Sample Code
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; Assemble options needed: /c /Fl
.MODEL small
.486
.STACK 4096
.DATA
data1 DB 100h DUP ('x')
data2 DB 100h DUP ('y')
data3 DW 100h DUP (1)
.CODE
start:
cmpxchg data1, ah
cmpxchg data1, ch
cmpxchg data1, dh
cmpxchg data1, bh
cmpxchg data2, dl
cmpxchg data3[ebx+2*esi],dx
END start
Additional query words: 6.00 6.00a 6.00b 6.10 6.10a buglist6.00a buglist6.00b buglist6.10 buglist6.10a fixlist6.11
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Keywords :
Technology : kbMASMsearch kbAudDeveloper kbMASM600 kbMASM600a kbMASM600b
Version : :6.0,6.0a,6.0b,6.10,6.10a
Solution Type : kbfix
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