opcodeda.java

這是一個8051的模擬器 以java寫成

/**
 * Projet de langage JAVA IFITEP 3 2005 - Simulateur 8051 
 * <p> 
 * D閒inition de l'instruction DA.
 * Cf.:
 *  - documentation technique 8051
 *  - Ouvrage "Microcontroleur 8051 et 8052", edition Dunod
 *  
 * @author Matthieu SIMON
 * @version 1.0 du 14/06/05
 */
public class OpcodeDA extends Opcode {
	public void execute(CORE_CPU8051 cpu) throws OpcodeException {
		int a;
		if(decodeAddressingMode(cpu.getCurrentLine().getOperand(1)) != CORE_CPU8051.ACC)
			throw new OpcodeException(this, "Bad Addressing Mode");
		a = CORE_CPU8051.internalDataMem[CORE_CPU8051.ACC];
		
		byte tmp = (byte)(a&0x0F);
		if(tmp > 9 || (CORE_CPU8051.internalDataMem[CORE_CPU8051.PSW]&0x40) != 0) // AC flag is set
			if((tmp = (byte)(tmp + 6)) > 15)
				CORE_CPU8051.internalDataMem[CORE_CPU8051.PSW] |= 0x80; // set carry flag
		tmp &= 0x0F;
		
		a = ((a>>4)&0x0F) + ((CORE_CPU8051.internalDataMem[CORE_CPU8051.PSW]>>7)&1);
		if(a > 9 || (CORE_CPU8051.internalDataMem[CORE_CPU8051.PSW]&0x80) != 0) // overflow is set
			if((a = (a + 6)) > 15)
				CORE_CPU8051.internalDataMem[CORE_CPU8051.PSW] |= 0x80; // set carry flag
		a &= 0x0F;
		CORE_CPU8051.internalDataMem[CORE_CPU8051.ACC] = (byte)(((a<<4)&0xF0) | tmp);		
		cpu.incCyclesCount(1);
	}
}