[Boost-commit] svn:boost r62924 - sandbox/SOC/2010/bits_and_ints/boost/integer

Subject: [Boost-commit] svn:boost r62924 - sandbox/SOC/2010/bits_and_ints/boost/integer
From: muriloufg_at_[hidden]
Date: 2010-06-13 19:36:06

Author: murilov
Date: 2010-06-13 19:36:03 EDT (Sun, 13 Jun 2010)
New Revision: 62924
URL: http://svn.boost.org/trac/boost/changeset/62924

Log:
Added overload in interleave function for accepting 8-bit (returning 16-bit) and 16-bit (returning 32-bit) integers as parameter.
Text files modified: 
   sandbox/SOC/2010/bits_and_ints/boost/integer/interleave.hpp |    61 ++++++++++++++++++++++++++++++--------- 
   1 files changed, 47 insertions(+), 14 deletions(-)

Modified: sandbox/SOC/2010/bits_and_ints/boost/integer/interleave.hpp
==============================================================================
--- sandbox/SOC/2010/bits_and_ints/boost/integer/interleave.hpp	(original)
+++ sandbox/SOC/2010/bits_and_ints/boost/integer/interleave.hpp	2010-06-13 19:36:03 EDT (Sun, 13 Jun 2010)
@@ -12,6 +12,8 @@
 
 #include <boost/utility/enable_if.hpp>
 #include <boost/type_traits/is_integral.hpp>
+#include <boost/cstdint.hpp>
+
 
 /*
  *	Bit interleaving functions.
@@ -22,7 +24,7 @@
  *		b = 10; // 0000 1010
  *		z = interleave(a, b); // z = 102
  *		
- *      a = 0 0 0 0 0 1 0 1
+ *		a = 0 0 0 0 0 1 0 1
  *		b =  0 0 0 0 1 0 1 0
  *		z = 0000000001100110
  */
@@ -30,24 +32,26 @@
 namespace boost 
 {
 
+/*
+ *	Interleave two 16-bit integral types and returns the bits interleaved in an
+ *		uint32_t.
+ */
 template <typename T>
-inline typename enable_if_c<is_integral<T>::type::value && sizeof(T) == 4, T>::type
+inline typename enable_if_c<is_integral<T>::type::value && sizeof(T) == 2, uint32_t>::type
 interleave(T x, T y)
 {
-	// puts the byte 2 in the byte 4
-	// and the byte 3 in the byte 5
+	uint32_t a(x), b(y);
+	
+	// puts the byte 2 in the byte 4 and the byte 3 in the byte 5
         a = (a | (a << 8)) & 0x00FF00FF;
         
-	// puts the bytes in alternate
-	// bytes
+	// now the original bytes of x are in alternate bytes
         a = (a | (a << 4)) & 0x0F0F0F0F;
         
-	// now the original bits are in
-	// the lowest 2 bits of the nibbles
+	// now the original bits of x are in the lowest 2 bits of the nibbles
         a = (a | (a << 2)) & 0x33333333;
         
-	// now the original bits are in 
-	// the even bits
+	// now the original bits are in the even bits
         a = (a | (a << 1)) & 0x55555555;
         
         // do the same with b
@@ -55,15 +59,44 @@
         b = (b | (b << 4)) & 0x0F0F0F0F;
         b = (b | (b << 2)) & 0x33333333;
         b = (b | (b << 1)) & 0x55555555;
-	// now the original bits are in
-	// the odd bits
+	
+	// now the original bits are in the odd bits
         b <<= 1;
 
-	// the result is the union of
-	// a and b bits
+	// the result is the union of a and b bits
         return (a | b);
 }
 
+/*
+ *	Interleave two 8-bit integral types and returns the bits interleaved in an
+ *		uint16_t.
+ */
+template <typename T>
+inline typename enable_if_c<is_integral<T>::type::value && sizeof(T) == 1, uint16_t>::type
+interleave(T x, T y)
+{
+	uint16_t a(x), b(y);
+	
+	// now the original bytes are in alternate bytes
+	a = (a | (a << 4)) & 0x0F0F;
+	
+	// now the original bits are in the lowest 2 bits of the nibbles
+	a = (a | (a << 2)) & 0x3333;
+	
+	// now the original bits are in the even bits
+	a = (a | (a << 1)) & 0x5555;
+	
+	// do the same with b
+	b = (b | (b << 4)) & 0x0F0F;
+	b = (b | (b << 2)) & 0x3333;
+	b = (b | (b << 1)) & 0x5555;
+	
+	// now the original bits are inthe odd bits
+	b <<= 1;
+	
+	// the result is the union of a and b bits
+	return (a | b);
 }
 
+}
 #endif
\ No newline at end of file