Module kala.compress.compressors.pack200
Package kala.compress.harmony.unpack200.bytecode

Class ByteCode

  • public class ByteCode
extends ClassFileEntry
    A bytecode class file entry.

    • Field Detail

      • noArgByteCodes

        private static ByteCode[] noArgByteCodes

      • nestedPositions

        private int[][] nestedPositions

      • rewrite

        private int[] rewrite

      • byteCodeOffset

        private int byteCodeOffset

      • byteCodeTargets

        private int[] byteCodeTargets

    • Constructor Detail

      • ByteCode

        protected ByteCode​(int opcode)

      • ByteCode

        protected ByteCode​(int opcode,
                   ClassFileEntry[] nested)

    • Method Detail

      • getByteCode

        public static ByteCode getByteCode​(int opcode)

      • applyByteCodeTargetFixup

        public void applyByteCodeTargetFixup​(CodeAttribute codeAttribute)
        Some ByteCodes (in particular, those with labels need to be fixed up after all the bytecodes in the CodeAttribute have been added. (This can't be done beforehand because the CodeAttribute needs to be complete before targets can be assigned.)
        Parameters:
        codeAttribute - the code attribute

      • doWrite

        protected void doWrite​(java.io.DataOutputStream dos)
                throws java.io.IOException
        Specified by:
        doWrite in class ClassFileEntry
        Throws:
        java.io.IOException

      • equals

        public boolean equals​(java.lang.Object obj)
        Specified by:
        equals in class ClassFileEntry

      • extractOperands

        public void extractOperands​(OperandManager operandManager,
                            Segment segment,
                            int codeLength)

      • getByteCodeForm

        protected ByteCodeForm getByteCodeForm()

      • getByteCodeIndex

        public int getByteCodeIndex()

      • getByteCodeTargets

        public int[] getByteCodeTargets()

      • getLength

        public int getLength()

      • getName

        public java.lang.String getName()

      • getNestedPosition

        public int[] getNestedPosition​(int index)

      • getNestedPositions

        public int[][] getNestedPositions()

      • getOpcode

        public int getOpcode()

      • getRewrite

        public int[] getRewrite()
        Some bytecodes (the ones with variable lengths) can't have a static rewrite array - they need the ability to update the array. This method permits their associated bytecode formst to query their rewrite array. Note that this should not be called from bytecodes which have a static rewrite; use the table in ByteCodeForm instead to specify those rewrites.
        Returns:
        Some bytecodes.

      • hasMultipleByteCodes

        public boolean hasMultipleByteCodes()
        This method will answer true if the receiver is a multi-bytecode instruction (such as aload0_putfield_super); otherwise, it will answer false.
        Returns:
        boolean true if multibytecode, false otherwise

      • nestedMustStartClassPool

        public boolean nestedMustStartClassPool()

      • setByteCodeIndex

        public void setByteCodeIndex​(int byteCodeOffset)
        ByteCodes may need to know their position in the code array (in particular, label byte codes need to know where they are in order to calculate their targets). This method lets the CodeAttribute specify where the byte code is. Since there are no aload0+label instructions, this method doesn't worry about multioperation bytecodes.
        Parameters:
        byteCodeOffset - int position in code array.

      • setByteCodeTargets

        public void setByteCodeTargets​(int[] byteCodeTargets)
        Some ByteCodes (in particular, those with labels) have to keep track of byteCodeTargets. These are initially offsets in the CodeAttribute array relative to the byteCodeOffset, but later get fixed up to point to the absolute position in the CodeAttribute array. This method sets the targets.
        Parameters:
        byteCodeTargets - int index in array

      • setNestedPositions

        public void setNestedPositions​(int[][] nestedPositions)
        nestedPositions is an array of arrays of ints. Each subarray specifies a position of a nested element (from the nested[] array) and the length of that element. For instance, one might have a nested of: {CPClass java/lang/Foo, CPFloat 3.14} The nestedPositions would then be: {{0,2},{2,2}} In other words, when the bytecode is resolved, the CPClass will be resolved to an int and inserted at position 0 and 1 of the rewrite arguments (the first occurrences of -1). The CPFloat will be resolved to an int position and inserted at positions 2 and 3 of the rewrite arguments.
        Parameters:
        nestedPositions - Each subarray specifies a position of a nested element (from the nested[] array) and the length of that element.

      • setOperand2Bytes

        public void setOperand2Bytes​(int operand,
                             int position)
        Given an int operand, set the rewrite bytes for that position and the one immediately following it to a high-byte, low-byte encoding of the operand.
        Parameters:
        operand - int to set the rewrite bytes to
        position - int position in the operands of the rewrite bytes. For a rewrite array of {100, -1, -1, -1} position 0 is the first -1, position 1 is the second -1, etc.

      • setOperandByte

        public void setOperandByte​(int operand,
                           int position)
        Given an int operand, treat it as a byte and set the rewrite byte for that position to that value. Mask of anything beyond 0xFF.
        Parameters:
        operand - int to set the rewrite byte to (unsigned)
        position - int position in the operands of the rewrite bytes. For a rewrite array of {100, -1, -1, -1} position 0 is the first -1, position 1 is the second -1, etc.

      • setOperandBytes

        public void setOperandBytes​(int[] operands)
        Given an array of ints which correspond to bytes in the operand of the bytecode, set the rewrite bytes of the operand to be the appropriate values. All values in operands[] will be masked with 0xFF so they fit into a byte.
        Parameters:
        operands - int[] rewrite operand bytes

      • setOperandSigned2Bytes

        public void setOperandSigned2Bytes​(int operand,
                                   int position)
        This is just like setOperandInt, but takes special care when the operand is less than 0 to make sure it's written correctly.
        Parameters:
        operand - int to set the rewrite bytes to
        position - int position of the operands in the rewrite bytes

      • setRewrite

        public void setRewrite​(int[] rewrite)
        Some bytecodes (the ones with variable lengths) can't have a static rewrite array - they need the ability to update the array. This method permits that. Note that this should not be called from bytecodes which have a static rewrite; use the table in ByteCodeForm instead to specify those rewrites.
        Parameters:
        rewrite - Some bytecodes.