FIX: Using TYPE Operator in Indirect Memory Operand Gives A2056

• Microsoft Macro Assembler for MS-DOS, versions 5.1, 5.1a
• Microsoft Macro Assembler for OS/2, versions 5.1, 5.1a

SYMPTOMS

The Microsoft Macro Assembler (MASM) versions 5.10 and 5.10a may generate the following error when the TYPE operator is used in an indirect memory operand:

error A2056: Immediate mode illegal

RESOLUTION

Instead of using the TYPE operator in this situation, a workaround for this problem is to use an equate that is set to the same value. This workaround is also illustrated in the following sample code (by deleting the line where the error occurs and uncommenting the specified line to take its place):

STATUS

Microsoft 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

The TYPE operator returns a number that represents the type of an expression. This is normally the size of the variable in bytes. However, using the TYPE operator in an indirect memory operand of an instruction such as ADD causes the assembler to generate the A2056 error. The sample code below demonstrates this problem.

Sample Code

; Assemble options needed: none

.MODEL SMALL

.DATA
String DB "this is a test"
STYPE  EQU TYPE(String)

.CODE
       add WORD PTR [bx+10+TYPE(String)], 1
;       add WORD PTR [bx+10+STYPE], 1       ;uncomment for workaround
       end 

Additional query words: 5.10 5.10a buglist5.10 buglist5.10a fixlist6.00

Keywords :
Version : :5.1,5.1a
Platform :
Issue type :