IPrefix

IPrefix

IPrefix class is a representation of the various Instruction prefixes. All the known prefixes have already been created as objects using this class.
So generally you use those, instead of creating new instances of this class.

Table of Contents

• Available prefixes
• Properties
• Functions
  • is
  • toString
  • Wrappers

Available prefixes

Name	Description
CS	Segment override to Code Segment.
DS	Segment override to Data Segment.
ES	Segment override to Extra Segment.
FS	Segment override to General Segment 1.
GS	Segment override to General Segment 2.
SS	Segment override to Stack Segment.
OPCH	OPerand size CHange - 32 bit to 16, 64 bit to 128 etc.
AD16	ADdress override to 16 bit. Also used in float instructions for converting to lower size.
ILOCK	Repeat/LOCK to grant exclusive use of all shared memory.
IREPE	String manipulation - Repeat string operation.
IREPN	String manipulation - Repeat string operation.

Properties

All the objects listed above contain the following properties.

Property name	Description
Value	The underlying value as hex.

In addition the IPrefix class itself has a List member containing all the Values.

Functions

is

Checks whether the current prefix is the same as the one specified.

Syntax:

<obj>.is(pre)

Argument	Description
pre	The prefix to compare against.

Returns: true if pre is an IPrefix and the Value matches else false

toString

Override of toString to return the underlying Value as a hex.

Primarily used by the [Instr] class, while generating the instruction's hex equivalent.

Syntax;

<obj>.toString()

Wrappers

You may have noticed that the last 3 prefixes begin with an I. This is done intentionally to avoid conflict with the wrapper functions.

For the last 3 prefixes, they are usually written before the instructions themselves (in the truest sense of the word prefix).

To mimic this behavior in code as well, there are 4 wrapping functions available for them :

• LOCK
• REPE
• REPN
• REP (Just an alias for REPE needed for some of the string instructions)

For e.g.

REP(LODS(AX)) //this will add the REP prefix to loop the LODS instruction.

Further reading

• Inbuilt API
• Scripted API
• Writing scripts