[Android reverse] smali basics (1)

Dalvik instruction set

• register definition
  • .localsDefine the number of registers
• function definition
  • .methodstart of function
  • endend of function
• data manipulation instruction
  • move vA,vBAssign the value of the vB register to the vA register
  • move/16 vAA,vBBThe data width is defined as 16 bits
  • move-object vA,vBfor object assignment
  • move-object/16 vAA,vBBDefine data width
• return command
  • return vAAReturns the value of the vAA register
  • return-objectreturn object
• Data Definition Instructions
  • constdata definition
  • const-stringdefine a string
• Instance operation instruction
  • check-cast vAA,type@BBConvert the object reference of the vAA register to the specified type
  • instance-of vA,vB,type@CCIt will be judged whether the object reference of the vB register can be converted to the specified type, it is vA=1, anyway vA=0
  • new-instance vAA,type@AAAConstructs a new instance of the specified type
• Array manipulation instructions
  • array-length vA,vBGet the length of the array in the vB register, and assign the result to the vA register
  • new-array vA,vB,type@CCConstructs an array of the specified type and size (vB), and assigns the result to vA
• abnormal
  • throw vAAThrows an exception of the type specified in the vAA register
• instruction jump
  • gotounconditional jump
  • packed-switch vAA,+BBBranch jump instruction, +BB only wants to increment the offset table
  • sparse-switch vAA,+BBbranch jump, irregular
• if jump instruction
  • if-test
    • eqequal
    • nenot equal to
    • ltless than
    • leless than or equal to
    • gegreater than greater than
    • gtmore than the
    • neznot equal to 0
    • nqzequal to 0
• comparison instruction
  • cmp-floatCompares two single-precision floating-point numbers
  • cmp-doublecompares double-precision floating-point numbers
  • cmp-longcompares two long integers
• field operation
  • Common fields start with "i"
    • igetread operation
    • iputwrite operation
  • Static fields start with "s"
    • sgetread operation
    • sputwrite operation
• method call
  • invoke-virtualcall instance virtual method
  • invoke-superInvoking the instance's superclass method
  • invoke-directInvoking the direct method of the instance
  • invoke-staticInvoking a static method on an instance