[Rawstudio-commit] rawspeed r157 - RawSpeed

[Klaus Post]

Author: post
Date: 2009-10-05 22:20:13 +0200 (Mon, 05 Oct 2009)
New Revision: 157

Modified:
   RawSpeed/BitPumpMSB.cpp
   RawSpeed/BitPumpMSB.h
   RawSpeed/OrfDecoder.cpp
Log:
Minor optimization to ORF-reader.

Modified: RawSpeed/BitPumpMSB.cpp
===================================================================
--- RawSpeed/BitPumpMSB.cpp     2009-10-05 15:23:19 UTC (rev 156)
+++ RawSpeed/BitPumpMSB.cpp     2009-10-05 20:20:13 UTC (rev 157)
@@ -65,6 +65,9 @@
 
 guint BitPumpMSB::getBits(guint nbits) {
   if (mLeft < nbits) {
+    if (nbits>24)
+      throw IOException("Invalid data, attempting to read more than 24 bits.");
+      
     fill();
   }
 
@@ -79,6 +82,9 @@
 
 guint BitPumpMSB::peekBits(guint nbits) {
   if (mLeft < nbits) {
+    if (nbits>24)
+      throw IOException("Invalid data, attempting to read more than 24 bits.");
+
     fill();
   }
 
@@ -132,6 +138,10 @@
   mLeft -= nbits;
 }
 
+void BitPumpMSB::skipBitsNoFill(unsigned int nbits) {
+  mLeft -= nbits;
+}
+
 unsigned char BitPumpMSB::getByte() {
   if (mLeft < 8) {
     fill();

Modified: RawSpeed/BitPumpMSB.h
===================================================================
--- RawSpeed/BitPumpMSB.h       2009-10-05 15:23:19 UTC (rev 156)
+++ RawSpeed/BitPumpMSB.h       2009-10-05 20:20:13 UTC (rev 157)
@@ -38,6 +38,7 @@
        guint peekBit();
   guint peekByte();
   void skipBits(guint nbits);
+  void skipBitsNoFill(guint nbits);
   __inline void checkPos()  { if (off>size) throw IOException("Out of buffer 
read");};        // Check if we have a valid position
        guchar getByte();
        guchar getByteSafe();

Modified: RawSpeed/OrfDecoder.cpp
===================================================================
--- RawSpeed/OrfDecoder.cpp     2009-10-05 15:23:19 UTC (rev 156)
+++ RawSpeed/OrfDecoder.cpp     2009-10-05 20:20:13 UTC (rev 157)
@@ -102,6 +102,16 @@
   guchar* data = mRaw->getData();
   gint pitch = mRaw->pitch;
 
+  /* Build a table to quickly look up "high" value */
+  gchar bittable[4096];
+  for (i = 0; i < 4096; i++) {
+    int b = i;
+    for (high = 0; high < 12; high++)
+      if ((b>>(11-high))&1)
+        break;
+      bittable[i] = high;
+  }
+
   s.skipBytes(7);
   BitPumpMSB bits(&s);
 
@@ -114,10 +124,13 @@
       carry = acarry[x & 1];
       i = 2 * (carry[2] < 3);
       for (nbits = 2 + i; (gushort) carry[0] >> (nbits + i); nbits++);
-      sign = bits.getBitNoFill() * -1;
-      low  = bits.getBitsNoFill(2);
-      for (high = 0; high < 12; high++)
-        if (bits.getBitNoFill()) break;
+      int b = bits.peekBitsNoFill(15);
+      sign = (b >> 14) * -1;
+      low  = (b >> 12) & 3;
+      high = bittable[b&4095];
+      // Skip bits used above.
+      bits.skipBitsNoFill(min(12+3, high + 1 + 3));
+
       if (high == 12)
         high = bits.getBits(16 - nbits) >> 1;
       carry[0] = (high << nbits) | bits.getBits(nbits);


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