FIX: LES Instruction Assembles IncorrectlyLast reviewed: September 10, 1997Article ID: Q29735 |
5.10 5.10a | 5.10 5.10a
MS-DOS | OS/2kbtool kbfixlist kbbuglist The information in this article applies to:
SYMPTOMSThe program example below demonstrates a problem with the LES instructions in Microsoft Macro Assembler (MASM) versions 5.1 and 5.1a. The first LES instruction (Parm1) assembles correctly, but the second instruction (Parm2) generates the error message:
error A2056: Immediate mode illegalThe only difference between the two instructions is the order of the arguments. In earlier versions of MASM, they produced identical code.
CAUSEThe problem is with the type operator and the way it handles registers inside brackets ([]). The type operator makes things a constant on the left of the expression. Parm1 works because it handles registers inside brackets differently. "TYPE x" turns bp into a constant; +10 then turns it back into an addressing mode. However, in Parm2, bp+10 has been turned into an addressing mode, which is then turned into a constant by "TYPE x". This difference is demonstrated in the sample code below.
STATUSMicrosoft has confirmed this to be a problem in MASM versions 5.1 and 5.1a. This problem was corrected in MASM version 6.0.
MORE INFORMATION
Sample Code; Assemble options needed: none
.MODEL smallx STRUC y DD ? x ENDS Parm1 EQU DWORD PTR [bp+TYPE x+10] Parm2 EQU DWORD PTR [bp+10+TYPE x] .CODE begin: les di,Parm1 les di,Parm2END begin
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Additional reference words: 5.10 5.10a buglist5.10 buglist5.10a fixlist6.00
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