Enums

Commands of this submenu are available in the enums window:

Please note that you can create bitfield definitions here.

You can also add a comment for the enum and for each enum member. In order to specify an enum comment, you must stand at the enum name. Comments are set using regular commands:

See also Edit submenu.

Add/Edit an enum

Action    name: AddEnum
 

 Action    name: EditEnum

These commands allow you to define and to edit an enum type. You need to specify:

        - name of enum
        - its serial number (1,2...)
        - representation of enum members

Each enum has its ID and a serial number. The ID is a number used to refer to the enum, while a serial number is used to order enums during output. Changing the serial number moves the enum to another place.

The serial number of an enum is displayed at the lower left corner of the window.

You can specify any number as a serial number, IDA will move the enum to the specified place.

        1 - the current enum becomes the first enum
        2 - the current enum becomes the second enum
        ...

You also need to specify representation of enum constants. You may choose from various number bases (hex,dec,oct,bin) and character constants.

You may specify the element width or leave it zero. Zero means the element width is not specified. The allowed widths are the powers of 2 in the range of 1..64.

Please note that you can create bitfield definitions here by checking the "bitfield" checkbox.

These command is available when you open the enums window.

See also How to Enter a Number.

Delete an enum type

 Action    name: DelEnum

This command deletes the current enum. Beware, when you delete an enum all references to it will be destroyed. Even if you recreate it later, you'll have to specify again all references to it.

This command is available when you open the enums window.

Define an enum member

Action    name: AddConst

This command allows you to define an enum member. An enum member is a symbolic constant. You have to specify its name and value. You cannot define more than 256 constants with the same value in an enum.

If the current enum is a bitfield, you need to specify the bitmask. To learn about bitmasks, read about bitfields.

Edit an enum member

Action    name: EditConst

This command allows you to rename an enum member. An enum member is a symbolic constant. Its name must be unique in the program.

To rename an enum type name, position the cursor over the name of the enum.

Delete an enum member

 Action    name: DelConst

Please remember that deleting a member also deletes all the information about the member, including comments, member name etc.

Bitfields

There is a special kind of enums: bitfields. A bitfield is an enum divided into bit groups. When you define a new symbolic constant in a bitfield, you need to specify the group to which the constant will belong to. By default, IDA proposes groups containing one bit each. If a group is not defined yet, it is automatically created when the first constant in the group is defined. For example:

        name    CONST1
        value   0x1
        mask    0x1

will define a constant named CONST1 with value 1 and will create a group containing only one bit. Another example. Let's consider the following definitions:

 #define OOF_SIGNMASK    0x0003
 #define   OOFS_IFSIGN   0x0000
 #define   OOFS_NOSIGN   0x0001
 #define   OOFS_NEEDSIGN 0x0002
 #define OOF_SIGNED      0x0004
 #define OOF_NUMBER      0x0008
 #define OOF_WIDTHMASK   0x0030
 #define   OOFW_IMM      0x0000
 #define   OOFW_16       0x0010
 #define   OOFW_32       0x0020
 #define   OOFW_8        0x0030
 #define OOF_ADDR        0x0040
 #define OOF_OUTER       0x0080
 #define OOF_ZSTROFF     0x0100

How do we describe this?

   name           value    mask   maskname

   OOFS_IFSIGN   0x0000   0x0003 OOF_SIGNMASK
   OOFS_NOSIGN   0x0001   0x0003 OOF_SIGNMASK
   OOFS_NEEDSIGN 0x0002   0x0003 OOF_SIGNMASK
 OOF_SIGNED      0x0004   0x0004
 OOF_NUMBER      0x0008   0x0008
   OOFW_IMM      0x0000   0x0030 OOF_WIDTHMASK
   OOFW_16       0x0010   0x0030 OOF_WIDTHMASK
   OOFW_32       0x0020   0x0030 OOF_WIDTHMASK
   OOFW_8        0x0030   0x0030 OOF_WIDTHMASK
 OOF_ADDR        0x0040   0x0040
 OOF_OUTER       0x0080   0x0080
 OOF_ZSTROFF     0x0100   0x0100

If a mask consists of more than one bit, it can have a name and a comment. A mask name can be set when a constant with the mask is being defined. IDA will display the mask names in a different color.

In order to use a bitfield in the program, just convert an instruction operand to enum. IDA will display the operand like this:

        mov     ax, 70h

will be replaced by

        mov     ax, OOFS_IFSIGN or OOFW_8 or OOF_ADDR

See also Enum window and Bitfields tutorial

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