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 * 1. Redistributions of source code must retain the above copyright notice, this list of
 * conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided
 * with the distribution.
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 * 3. Neither the name of the copyright holder nor the names of its contributors may be used to
 * endorse or promote products derived from this software without specific prior written
 * permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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package com.oracle.truffle.llvm.parser.macho;

import com.oracle.truffle.llvm.parser.filereader.ObjectFileReader;
import com.oracle.truffle.llvm.runtime.Magic;
import com.oracle.truffle.llvm.runtime.except.LLVMParserException;
import org.graalvm.polyglot.io.ByteSequence;

public final class MachOReader extends ObjectFileReader {

    private final boolean is64Bit;

    private MachOReader(ByteSequence buffer, boolean littleEndian, boolean is64Bit) {
        super(buffer, littleEndian);
        this.is64Bit = is64Bit;
    }

    public static MachOFile create(ByteSequence buffer) {
        int position = 0;

        int ret = buffer.byteAt(position++) & 0xff;
        ret = (ret << 8) | (buffer.byteAt(position++) & 0xff);
        ret = (ret << 8) | (buffer.byteAt(position++) & 0xff);
        ret = (ret << 8) | (buffer.byteAt(position++) & 0xff);
        long magic = Integer.toUnsignedLong(ret);

        if (!MachOFile.isMachOMagicNumber(magic)) {
            throw new LLVMParserException("Invalid Mach-O file!");
        }

        boolean is64Bit = isMachO64MagicNumber(magic);
        MachOReader reader = new MachOReader(buffer, isReversedByteOrder(magic), is64Bit);
        reader.setPosition(position);
        MachOHeader header = MachOHeader.create(reader);
        MachOLoadCommandTable loadCommandTable = MachOLoadCommandTable.create(header, reader);
        return new MachOFile(header, loadCommandTable, reader.byteSequence);
    }

    public boolean is64Bit() {
        return is64Bit;
    }

    private static boolean isMachO64MagicNumber(long magic) {
        return magic == Magic.MH_MAGIC_64.magic || magic == Magic.MH_CIGAM_64.magic;
    }

    private static boolean isReversedByteOrder(long magic) {
        return magic == Magic.MH_CIGAM.magic || magic == Magic.MH_CIGAM_64.magic;
    }

}