Add stream avail() methods

Makes it more readable to write code that needs to know how much
data/space is available in a stream.

common/rdr/FdInStream.cxx

@@ -126,7 +126,7 @@ size_t FdInStream::overrun(size_t itemSize, size_t nItems, bool wait)
   }
 
   size_t nAvail;
-  nAvail = (end - ptr) / itemSize;
+  nAvail = avail() / itemSize;
   if (nAvail < nItems)
     return nAvail;
 

common/rdr/FdOutStream.cxx

@@ -129,7 +129,7 @@ size_t FdOutStream::overrun(size_t itemSize, size_t nItems)
   flush();
 
   // Still not enough space?
-  if (itemSize > (size_t)(end - ptr)) {
+  if (itemSize > avail()) {
     // Can we shuffle things around?
     // (don't do this if it gains us less than 25%)
     if (((size_t)(sentUpTo - start) > bufSize / 4) &&
@@ -150,7 +150,7 @@ size_t FdOutStream::overrun(size_t itemSize, size_t nItems)
   }
 
   size_t nAvail;
-  nAvail = (end - ptr) / itemSize;
+  nAvail = avail() / itemSize;
   if (nAvail < nItems)
     return nAvail;
 

common/rdr/FileInStream.cxx

@@ -81,7 +81,7 @@ size_t FileInStream::overrun(size_t itemSize, size_t nItems, bool wait)
   }
 
   size_t nAvail;
-  nAvail = (end - ptr) / itemSize;
+  nAvail = avail() / itemSize;
   if (nAvail < nItems)
     return nAvail;
 

common/rdr/HexInStream.cxx

@@ -91,7 +91,7 @@ size_t HexInStream::overrun(size_t itemSize, size_t nItems, bool wait) {
   offset += ptr - start;
   ptr = start;
 
-  while ((size_t)(end - ptr) < itemSize) {
+  while (avail() < itemSize) {
     size_t n = in_stream.check(2, 1, wait);
     if (n == 0) return 0;
     const U8* iptr = in_stream.getptr();
@@ -111,7 +111,7 @@ size_t HexInStream::overrun(size_t itemSize, size_t nItems, bool wait) {
   }
 
   size_t nAvail;
-  nAvail = (end - ptr) / itemSize;
+  nAvail = avail() / itemSize;
   if (nAvail < nItems)
     return nAvail;
 

common/rdr/HexOutStream.cxx

@@ -103,7 +103,7 @@ HexOutStream::overrun(size_t itemSize, size_t nItems) {
   writeBuffer();
 
   size_t nAvail;
-  nAvail = (end - ptr) / itemSize;
+  nAvail = avail() / itemSize;
   if (nAvail < nItems)
     return nAvail;
 

common/rdr/InStream.h

@@ -35,6 +35,14 @@ namespace rdr {
 
     virtual ~InStream() {}
 
+    // avail() returns the number of bytes that are currenctly directly
+    // available from the stream.
+
+    inline size_t avail()
+    {
+      return end - ptr;
+    }
+
     // check() ensures there is buffer data for at least one item of size
     // itemSize bytes.  Returns the number of items in the buffer (up to a
     // maximum of nItems).  If wait is false, then instead of blocking to wait
@@ -48,11 +56,11 @@ namespace rdr {
       if (itemSize == 0 || nItems == 0)
         return 0;
 
-      if (itemSize > (size_t)(end - ptr))
+      if (itemSize > avail())
         return overrun(itemSize, nItems, wait);
 
       // itemSize cannot be zero at this point
-      nAvail = (end - ptr) / itemSize;
+      nAvail = avail() / itemSize;
       if (nAvail < nItems)
         return nAvail;
 

common/rdr/OutStream.h

@@ -40,6 +40,14 @@ namespace rdr {
 
     virtual ~OutStream() {}
 
+    // avail() returns the number of bytes that currently be written to the
+    // stream without any risk of blocking.
+
+    inline size_t avail()
+    {
+      return end - ptr;
+    }
+
     // check() ensures there is buffer space for at least one item of size
     // itemSize bytes.  Returns the number of items which fit (up to a maximum
     // of nItems).
@@ -48,10 +56,10 @@ namespace rdr {
     {
       size_t nAvail;
 
-      if (itemSize > (size_t)(end - ptr))
+      if (itemSize > avail())
         return overrun(itemSize, nItems);
 
-      nAvail = (end - ptr) / itemSize;
+      nAvail = avail() / itemSize;
       if (nAvail < nItems)
         return nAvail;
 

common/rdr/RandomStream.cxx

@@ -124,7 +124,7 @@ size_t RandomStream::overrun(size_t itemSize, size_t nItems, bool wait) {
   }
 
   size_t nAvail;
-  nAvail = (end - ptr) / itemSize;
+  nAvail = avail() / itemSize;
   if (nAvail < nItems)
     return nAvail;
 

common/rdr/TLSInStream.cxx

@@ -100,7 +100,7 @@ size_t TLSInStream::overrun(size_t itemSize, size_t nItems, bool wait)
   }
 
   size_t nAvail;
-  nAvail = (end - ptr) / itemSize;
+  nAvail = avail() / itemSize;
   if (nAvail < nItems)
     return nAvail;
 

common/rdr/TLSOutStream.cxx

@@ -101,7 +101,7 @@ size_t TLSOutStream::overrun(size_t itemSize, size_t nItems)
   flush();
 
   size_t nAvail;
-  nAvail = (end - ptr) / itemSize;
+  nAvail = avail() / itemSize;
   if (nAvail < nItems)
     return nAvail;
 

common/rdr/ZlibInStream.cxx

@@ -108,13 +108,13 @@ size_t ZlibInStream::overrun(size_t itemSize, size_t nItems, bool wait)
   end -= ptr - start;
   ptr = start;
 
-  while ((size_t)(end - ptr) < itemSize) {
+  while (avail() < itemSize) {
     if (!decompress(wait))
       return 0;
   }
 
   size_t nAvail;
-  nAvail = (end - ptr) / itemSize;
+  nAvail = avail() / itemSize;
   if (nAvail < nItems)
     return nAvail;
 
@@ -136,7 +136,7 @@ bool ZlibInStream::decompress(bool wait)
   size_t n = underlying->check(1, 1, wait);
   if (n == 0) return false;
   zs->next_in = (U8*)underlying->getptr();
-  zs->avail_in = underlying->getend() - underlying->getptr();
+  zs->avail_in = underlying->avail();
   if (zs->avail_in > bytesIn)
     zs->avail_in = bytesIn;
 

common/rdr/ZlibOutStream.cxx

@@ -106,7 +106,7 @@ size_t ZlibOutStream::overrun(size_t itemSize, size_t nItems)
 
   checkCompressionLevel();
 
-  while ((size_t)(end - ptr) < itemSize) {
+  while (avail() < itemSize) {
     zs->next_in = start;
     zs->avail_in = ptr - start;
 
@@ -128,7 +128,7 @@ size_t ZlibOutStream::overrun(size_t itemSize, size_t nItems)
   }
 
   size_t nAvail;
-  nAvail = (end - ptr) / itemSize;
+  nAvail = avail() / itemSize;
   if (nAvail < nItems)
     return nAvail;
 
@@ -148,7 +148,7 @@ void ZlibOutStream::deflate(int flush)
   do {
     underlying->check(1);
     zs->next_out = underlying->getptr();
-    zs->avail_out = underlying->getend() - underlying->getptr();
+    zs->avail_out = underlying->avail();
 
 #ifdef ZLIBOUT_DEBUG
     fprintf(stderr,"zos: calling deflate, avail_in %d, avail_out %d\n",

common/rfb/JpegCompressor.cxx

@@ -85,7 +85,7 @@ JpegInitDestination(j_compress_ptr cinfo)
 
   jc->clear();
   dest->pub.next_output_byte = jc->getptr();
-  dest->pub.free_in_buffer = jc->getend() - jc->getptr();
+  dest->pub.free_in_buffer = jc->avail();
 }
 
 static boolean
@@ -97,7 +97,7 @@ JpegEmptyOutputBuffer(j_compress_ptr cinfo)
   jc->setptr(jc->getend());
   jc->overrun(jc->getend() - jc->getstart(), 1);
   dest->pub.next_output_byte = jc->getptr();
-  dest->pub.free_in_buffer = jc->getend() - jc->getptr();
+  dest->pub.free_in_buffer = jc->avail();
 
   return TRUE;
 }