optimize color write and increase bitblt limits

the color write improvements appears to give clients a 90% speed up on loading color nbt

src/main/resources/application.conf

@@ -1598,8 +1598,8 @@ opencomputers {
     # This setting assigns the budget call cost to invoke bitblt to write vram
     # to a screen. Video ram can bitblit to a screen which can cause real life
     # network laod the defaults settings put bitblit network impact close to gpu.set
-    # Increase these values to throttle bitblt more. These values appear inverted
-    # but the cost of bitblt is based on the max resolution of the device
-    bitbltCosts: [ 1, 2, 8 ]
+    # Increase these values to throttle bitblt more. The cost tier N is bitbltCost * 2^(tier)
+    # default is .5, which gives: .5, 1, 4
+    bitbltCost: 0.5
   }
 }

src/main/scala/li/cil/oc/Settings.scala

@@ -476,12 +476,7 @@ class Settings(val config: Config) {
       Array(1, 2, 3)
   }
 
-  val bitbltCosts: Array[Double] = Array(config.getDoubleList("gpu.bitbltCosts"): _*) match {
-    case Array(tier1, tier2, tier3) => Array(tier1: Double, tier2: Double, tier3: Double)
-    case _ =>
-      OpenComputers.log.warn("Bad number of bitblit costs (expected 3), ignoring.")
-      Array(1, 2, 8)
-  }
+  val bitbltCost: Double = if (config.hasPath("gpu.bitbltCost")) config.getDouble("gpu.bitbltCost") else 0.5
 }
 
 object Settings {

src/main/scala/li/cil/oc/server/component/GraphicsCard.scala

@@ -71,7 +71,7 @@ class GraphicsCard(val tier: Int) extends prefab.ManagedEnvironment with DeviceI
   // These are dirty page bitblt budget costs
   // a single bitblt can send a screen of data, which is n*set calls where set is writing an entire line
   // So for each tier, we multiple the set cost with the number of lines the screen may have
-  final val bitbltCost: Double = Settings.get.bitbltCosts(0 max tier min 2)
+  final val bitbltCost: Double = Settings.get.bitbltCost * scala.math.pow(2, tier)
   final val totalVRAM: Double = (maxResolution._1 * maxResolution._2) * Settings.get.vramSizes(0 max tier min 2)
 
   var budgetExhausted: Boolean = false // for especially expensive calls, bitblt

src/main/scala/li/cil/oc/util/NbtDataStream.scala

@@ -0,0 +1,49 @@
+package li.cil.oc.util
+
+import net.minecraft.nbt.NBTTagCompound
+
+object NbtDataStream {
+  def getShortArray(nbt: NBTTagCompound, key: String, array2d: Array[Array[Short]], w: Int, h: Int) : Boolean = {
+    if (!nbt.hasKey(key)) {
+      return false
+    }
+
+    val rawByteReader = new java.io.ByteArrayInputStream(nbt.getByteArray(key))
+    val memReader = new java.io.DataInputStream(rawByteReader)
+    for (y <- 0 until h) {
+      for (x <- 0 until w) {
+        if (2 > memReader.available()) {
+          return true // not great, but get out now
+        }
+        array2d(y)(x) = memReader.readShort()
+      }
+    }
+    true
+  }
+
+  def getIntArrayLegacy(nbt: NBTTagCompound, key: String, array2d: Array[Array[Short]], w: Int, h: Int) : Boolean = {
+    if (!nbt.hasKey(key)) {
+      return false
+    }
+    // legacy format
+    val c = nbt.getIntArray(key)
+    for (y <- 0 until h) {
+      val rowColor = array2d(y)
+      for (x <- 0 until w) {
+        val index = x + y * w
+        if (index >= c.length) {
+          return true // not great, but, the read at least started
+        }
+        rowColor(x) = c(index).toShort
+      }
+    }
+    true
+  }
+
+  def setShortArray(nbt: NBTTagCompound, key: String, array: Array[Short]): Unit = {
+    val rawByteWriter = new java.io.ByteArrayOutputStream()
+    val memWriter = new java.io.DataOutputStream(rawByteWriter)
+    array.foreach(memWriter.writeShort(_))
+    nbt.setByteArray(key, rawByteWriter.toByteArray)
+  }
+}

src/main/scala/li/cil/oc/util/TextBuffer.scala

@@ -262,15 +262,8 @@ class TextBuffer(var width: Int, var height: Int, initialFormat: PackedColor.Col
     foreground = PackedColor.Color(nbt.getInteger("foreground"), nbt.getBoolean("foregroundIsPalette"))
     background = PackedColor.Color(nbt.getInteger("background"), nbt.getBoolean("backgroundIsPalette"))
 
-    val c = nbt.getIntArray("color")
-    for (i <- 0 until h) {
-      val rowColor = color(i)
-      for (j <- 0 until w) {
-        val index = j + i * w
-        if (index < c.length) {
-          rowColor(j) = c(index).toShort
-        }
-      }
+    if (!NbtDataStream.getShortArray(nbt, "color_bytes", color, w, h)) {
+      NbtDataStream.getIntArrayLegacy(nbt, "color", color, w, h)
     }
   }
 
@@ -291,10 +284,10 @@ class TextBuffer(var width: Int, var height: Int, initialFormat: PackedColor.Col
     nbt.setInteger("background", _background.value)
     nbt.setBoolean("backgroundIsPalette", _background.isPalette)
 
-    nbt.setTag("color", new NBTTagIntArray(color.flatten.map(_.toInt)))
+    NbtDataStream.setShortArray(nbt, "color_bytes", color.flatten.map(_.toShort))
   }
 
-  override def toString = {
+  override def toString: String = {
     val b = StringBuilder.newBuilder
     if (buffer.length > 0) {
       b.appendAll(buffer(0))