1 files changed, 77 insertions, 1 deletions
diff --git a/src/main/java/org/openslx/libvirt/domain/DomainUtils.java b/src/main/java/org/openslx/libvirt/domain/DomainUtils.java
index 2462371..34dcdd6 100644
--- a/src/main/java/org/openslx/libvirt/domain/DomainUtils.java
+++ b/src/main/java/org/openslx/libvirt/domain/DomainUtils.java
@@ -2,9 +2,11 @@ package org.openslx.libvirt.domain;
 
 import java.math.BigInteger;
 
+import org.openslx.libvirt.domain.device.HostdevPciDeviceAddress;
+
 /**
  * Collection of helper functions to maintain a Libvirt domain XML document.
- * 
+ *
  * @author Manuel Bentele
  * @version 1.0
  */
@@ -115,4 +117,78 @@ public final class DomainUtils
 
 		return value.divide( dividend ).toString();
 	}
+
+	/**
+	 * Builds a PCI slot usage map from all devices in the given domain configuration.
+	 * <p>
+	 * The returned array tracks which PCI device slots are in use on the primary bus
+	 * (domain 0, bus 0). Array indices correspond to device numbers (0-63), with:
+	 * </p>
+	 * <ul>
+	 *   <li>{@code 0} = slot is free</li>
+	 *   <li>{@code >0} = slot is occupied (value encodes domain:bus:device lookup)</li>
+	 * </ul>
+	 * <p>
+	 * Slots 0 and 1 are pre-marked as reserved.
+	 * </p>
+	 *
+	 * @param config domain configuration to scan for existing PCI devices
+	 * @return array of size 64 tracking PCI slot usage
+	 */
+	public static int[] buildPciSlotUsageMap( Domain config )
+	{
+		int[] inUse = new int[ 64 ];
+		inUse[ 0 ] = Integer.MAX_VALUE;
+		inUse[ 1 ] = Integer.MAX_VALUE;
+
+		for ( org.openslx.libvirt.domain.device.Device dev : config.getDevices() ) {
+			HostdevPciDeviceAddress target = dev.getPciTarget();
+			if ( target == null )
+				continue;
+			if ( target.getPciDomain() != 0 || target.getPciBus() != 0 )
+				continue; // Ignore non-primary bus
+			if ( target.getPciDevice() >= inUse.length )
+				continue;
+			inUse[ target.getPciDevice() ] = Integer.MAX_VALUE;
+		}
+
+		return inUse;
+	}
+
+	/**
+	 * Finds a free PCI device slot on the primary bus (domain 0, bus 0) that doesn't
+	 * collide with existing device addresses.
+	 * <p>
+	 * The method first checks if the exact same PCI address was already assigned
+	 * (for reuse), otherwise returns the first free slot starting from device 2.
+	 * </p>
+	 *
+	 * @param inUse PCI slot usage map from {@link #buildPciSlotUsageMap(Domain)}
+	 * @param pciDeviceAddress original PCI device address to find a slot for
+	 * @return free PCI device number (0-63) for assignment
+	 * @throws IllegalStateException if no free PCI slot is available
+	 */
+	public static int findFreePciDeviceSlot( int[] inUse, HostdevPciDeviceAddress pciDeviceAddress )
+	{
+		int devAddr;
+		int firstFree = -1;
+		int lookup = ( pciDeviceAddress.getPciDomain() << 16 )
+				| ( pciDeviceAddress.getPciBus() << 8 )
+				| ( pciDeviceAddress.getPciDevice() );
+
+		for ( devAddr = 0; devAddr < inUse.length; ++devAddr ) {
+			if ( firstFree == -1 && inUse[ devAddr ] == 0 ) {
+				firstFree = devAddr;
+			} else if ( inUse[ devAddr ] == lookup ) {
+				return devAddr;
+			}
+		}
+
+		if ( firstFree == -1 ) {
+			throw new IllegalStateException( "No free PCI device slot available" );
+		}
+
+		inUse[ firstFree ] = lookup;
+		return firstFree;
+	}
 }