org.eclipse.cdt.debug.edc.arm/src/org/eclipse/cdt/debug/edc/internal/arm/ARMElf.java

/*******************************************************************************
 * Copyright (c) 2009, 2010 Nokia and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 * Nokia - Initial API and implementation
 *******************************************************************************/
package org.eclipse.cdt.debug.edc.internal.arm;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import org.eclipse.cdt.core.IAddress;
import org.eclipse.cdt.debug.edc.internal.symbols.elf.BufferedRandomReadAccessFile;
import org.eclipse.cdt.debug.edc.internal.symbols.elf.Elf;
import org.eclipse.cdt.utils.Addr32;
import org.eclipse.cdt.utils.Addr64;

/**
 * ARM Elf provides extra "mappings" in the symbol table to help distinguish
 * between ARM and Thumb code. These extra symbols are mapped to the same
 * address as the real symbol, but have a NULL type. The symbols of interest are
 * $a and $t, for ARM and Thumb modes respectively.
 */
public class ARMElf extends Elf {

	private Map<IAddress, Symbol> zeroSymbols = new HashMap<IAddress, Symbol>();
	
	public ARMElf(String filename, boolean isLE) throws IOException {
		super(new BufferedRandomReadAccessFile(filename, isLE), filename, 0);
		readSymbols();
	}

	/**
	 * Record the interesting symbols once
	 */
	private void readSymbols() throws IOException {
		Elf.Section symtab = getSectionByName(".symtab"); //$NON-NLS-1$

		int numSyms = 1;
		if (symtab.sh_entsize != 0) {
			numSyms = (int) symtab.sh_size / (int) symtab.sh_entsize;
		}
		long offset = symtab.sh_offset;
		for (int c = 0; c < numSyms; offset += symtab.sh_entsize, c++) {
			efile.seek(offset);
			Symbol symbol = new Symbol(symtab);
			switch (ehdr.e_ident[ELFhdr.EI_CLASS]) {
			case ELFhdr.ELFCLASS32: {
				byte[] addrArray = new byte[ELF32_ADDR_SIZE];

				symbol.st_name = efile.readIntE();
				efile.readFullyE(addrArray);
				symbol.st_value = new Addr32(addrArray);
				symbol.st_size = efile.readIntE();
				symbol.st_info = efile.readByte();
				symbol.st_other = efile.readByte();
				symbol.st_shndx = efile.readShortE();
			}
				break;
			case ELFhdr.ELFCLASS64: {
				byte[] addrArray = new byte[ELF64_ADDR_SIZE];

				symbol.st_name = efile.readIntE();
				symbol.st_info = efile.readByte();
				symbol.st_other = efile.readByte();
				symbol.st_shndx = efile.readShortE();
				efile.readFullyE(addrArray);
				symbol.st_value = new Addr64(addrArray);
				symbol.st_size = readUnsignedLong(efile);
			}
				break;
			case ELFhdr.ELFCLASSNONE:
			default:
				throw new IOException("Unknown ELF class " + ehdr.e_ident[ELFhdr.EI_CLASS]); //$NON-NLS-1$
			}

			if (symbol.st_size == 0) {
				if (!zeroSymbols.containsKey(symbol.st_value)) {
					zeroSymbols.put(symbol.st_value, symbol);
				}
			}
		}		
	}

	public String getMappingSymbolAtAddress(IAddress address) {
		// use the start address of the symbol and try to find
		// the matching mapping entry

		Symbol symbol = zeroSymbols.get(address);
		if (symbol == null)
			return null;
		
		return symbol.toString();
	}
}