Android Reverse base----Dalvik byte code

Refer to this Weibo, more details can be seen here

http://blog.csdn.net/dd864140130/article/details/52076515

Dalvik byte code

1, register bit 32 bit, 64-bit data (double) is represented by two adjacent 32 registers.

2. Two types: Basic types and reference types (objects and arrays)

What is the fully qualified name?

In the case of String, whose full name is Java.lang.String, then its fully qualified name is java/lang/string; that is, java.lang.String "." Replace with "/" and add a semicolon at the end ";" Make a terminator.

Dalvik byte code type descriptor

V void can only be used for return value types

Z Boolean logical value, returns True (True) False (false)

B byte byte type

Short integer type S

C Char Character type

I int integer type

J Long (64-bit) length integer

F Float Float Type

D double-precision floating point

L object Type, Java class

java->package.name.objectname;

Davik->lpackage/name/objectname

[Array type

Java->int[] int[][] three-dimensional array

davik->[i;   [[I; [[I;

Description of the field

The description of a field in Davik is divided into two types, a description of the base Type field, and a description of the reference type, but the same is true for the two:

Object type descriptor, field name: type descriptor;

For example, the Com.sbbic.Test class has a Name field of type string and an age field of type int, which is described as:

lcom/sbbic/test;->name:ljava/lang/string;

Lcom/sbbic/test;->age:i

Dalvik instruction Set

Data definition Directive Const

const-Assignment Method register name append content

Instructions	Describe
CONST/4 va,#+b	Assign a value to register VA after expanding the value symbol to 32
CONST-WIDE/16 VAA,#+BBBB	Expands the value symbol to 64-bit after assigning a register pair Vaa
Const-string Vaa,[email protected]	Assigning a value to a register by using a string index high walk string Vaa
Const-class Vaa,[email protected]	Get a reference to a class by type index assign to register VAA

Data manipulation Instructions Move

Instructions	Describe
Move VA,VB	The value of the VB register is assigned to the VA register, VA and VB registers are 4-bit
MOVE/FROM16 VAA,VBBBB	Assigns the value of the VBBBB register (16-bit) to the VAA register (7-bit), FROM16 indicates that the source register VBBBB is 16-bit
MOVE/16 VAAAA,VBBBB	Assigns the value of the register VBBBB to the VAAAA register, 16 means that the source register VBBBB and the target register VAAAA are 16-bit
Move-object VA,VB	The object reference in the VB register is assigned to the VA register, and the VA register and the VB Register are all 4-bit
Move-result VAA	Assigns a single (32-bit) non-object result of the previous invoke instruction (method call) operation to the VAA register
Move-result-wide VAA	Assigns a double-word (64-bit) non-object result of the previous invoke instruction operation to the VAA register
Mvoe-result-object VAA	Assigns the result of the object of the previous invoke instruction operation to the VAA register
Move-exception VAA	Saves the exception that occurred at the last runtime to the VAA register

3. Jump Instructions

If-eq	equals then jumps	==
If-ne	does not equal the jump	!=
If-lt	Less then jump	<
If-ge	is greater than or equal to jump	>=
If-gt	Jump if greater than	>
If-le	is less than or equal to jump	<=
Goto	Unconditional Jump
Switch	Branch Jump

Returns 0 Implementation jump

Android Reverse base----Dalvik byte code