Minor change.

Doc/comment in faust_bit_rev_permu.

src/algorithm/factorization/faust_bit_rev_permu.cpp

@@ -12,18 +12,19 @@ namespace Faust {
 
 		while(lower_mask < upper_mask)
 		{
-			for(unsigned int i=0;i<size;i++){
+			for(unsigned int i=0;i<size;i++)
+			{
 				lobit = (v[i] & lower_mask) >>(shift);
 				hibit = (v[i] & upper_mask)>>(n-shift-1);
 				if(lobit > hibit){
-					//lobit == 1, hibit == 0
-					v[i] ^= lower_mask;
-					v[i] |= upper_mask;
+					// swap lobit == 1, hibit == 0
+					v[i] ^= lower_mask; // 1 ^ 1 == 0 == hibit
+					v[i] |= upper_mask; // 0 | 1 == 1 == lobit
 				}
 				else if (lobit < hibit){
 					//swap lobit == 0, hibit == 1
-					v[i] |= lower_mask;
-					v[i] ^= upper_mask;
+					v[i] |= lower_mask; // 0 | 1 == 1 == hibit
+					v[i] ^= upper_mask; // 1 ^ 1 == 0 == lobit
 				}
 			}
 			lower_mask <<= 1;

src/algorithm/factorization/faust_bit_rev_permu.h

@@ -4,9 +4,9 @@ namespace Faust {
 	/**
 	 * \brief This function is only utility for faust_FFT.h(pp).
 	 *
-	 *  Init v to (1,..,2^n-1).
+	 *  Init v to (0,..,2^n-1).
 	 *  And proceeds with a bit reversal permutation.
-	 *  E.g. : if n = 3, v=(0, 1, 2, 3, 4, 5, 6, 7, 8) and becomes (0, 4, 2, 6, 1, 5, 3, 7).
+	 *  E.g. : if n = 3, v=(0, 1, 2, 3, 4, 5, 6, 7) and becomes (0, 4, 2, 6, 1, 5, 3, 7).
 	 */
 	void bit_rev_permu(unsigned int n, unsigned int* v, const bool initv=true);
 }