Re: [algogeeks] Reverse Bits
x = x16 | (0xx)16 this line exchanges ls 16bits with ms 16bits, i.e. 1 pair of 16bit this logic of exchanging bits is the used for 2 pairs of 8bits each, then for 4 pairs of 4bit, then for 8 pairs of 2 bit and finally 16 pairs of 1bit. On Fri, Aug 5, 2011 at 6:04 PM, rShetty rajeevr...@gmail.com wrote: This is the code to reverse the bits in an unsigned integer . Could anyone please explain the logic of this approach ? Thank You !! #define reverse(x) \ (x=x16|(0xx)16, \ x=(0xff00ff00x)8|(0x00ff00ffx)8, \ x=(0xf0f0f0f0x)4|(0x0f0f0f0fx)4, \ x=(0xx)2|(0xx)2, \ x=(0xx)1|(0xx)1) -- You received this message because you are subscribed to the Google Groups Algorithm Geeks group. To post to this group, send email to algogeeks@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en. -- You received this message because you are subscribed to the Google Groups Algorithm Geeks group. To post to this group, send email to algogeeks@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
Re: [algogeeks] Reverse Bits
Hi Rajeev, I follow similar approach. The basic logic is swap bits of a pair, then swap nibbles(2 bits) and then swap (4bits), 8bits and go on. So for ex. 0110 1101 1100 0101 In first step, I swap bits of each pair. So this becomes, Input - 0110 1101 1100 0101 output- 1001 1110 1100 1010 In second step, I swap 2bits Input - 1001 1110 1100 1010 output-0110 1011 0011 1010 I swap 4 bits now Input - 0110 1011 0011 1010 output-1011 0110 1010 0011 Now I swap 8bits Input - 1011 0110 1010 0011 output-1010 0011 1011 0110 So, now we have the bits in reverse order. First step I do this way x = ((x | 0x) 2) | (x2) | 0x; Next step similarly x = ((x | 0x) 4) | (x4) | 0x; This is the logic. Your code does the reverse way. Regards, Mithun On Fri, Aug 5, 2011 at 6:04 PM, rShetty rajeevr...@gmail.com wrote: This is the code to reverse the bits in an unsigned integer . Could anyone please explain the logic of this approach ? Thank You !! #define reverse(x) \ (x=x16|(0xx)16, \ x=(0xff00ff00x)8|(0x00ff00ffx)8, \ x=(0xf0f0f0f0x)4|(0x0f0f0f0fx)4, \ x=(0xx)2|(0xx)2, \ x=(0xx)1|(0xx)1) -- You received this message because you are subscribed to the Google Groups Algorithm Geeks group. To post to this group, send email to algogeeks@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en. -- Mithun.B.S M:9916775380 -- You received this message because you are subscribed to the Google Groups Algorithm Geeks group. To post to this group, send email to algogeeks@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
Re: [algogeeks] Reverse Bits
@mithun : Thanks On Fri, Aug 5, 2011 at 6:37 PM, mithun bs mithun...@gmail.com wrote: Hi Rajeev, I follow similar approach. The basic logic is swap bits of a pair, then swap nibbles(2 bits) and then swap (4bits), 8bits and go on. So for ex. 0110 1101 1100 0101 In first step, I swap bits of each pair. So this becomes, Input - 0110 1101 1100 0101 output- 1001 1110 1100 1010 In second step, I swap 2bits Input - 1001 1110 1100 1010 output-0110 1011 0011 1010 I swap 4 bits now Input - 0110 1011 0011 1010 output-1011 0110 1010 0011 Now I swap 8bits Input - 1011 0110 1010 0011 output-1010 0011 1011 0110 So, now we have the bits in reverse order. First step I do this way x = ((x | 0x) 2) | (x2) | 0x; Next step similarly x = ((x | 0x) 4) | (x4) | 0x; This is the logic. Your code does the reverse way. Regards, Mithun On Fri, Aug 5, 2011 at 6:04 PM, rShetty rajeevr...@gmail.com wrote: This is the code to reverse the bits in an unsigned integer . Could anyone please explain the logic of this approach ? Thank You !! #define reverse(x) \ (x=x16|(0xx)16, \ x=(0xff00ff00x)8|(0x00ff00ffx)8, \ x=(0xf0f0f0f0x)4|(0x0f0f0f0fx)4, \ x=(0xx)2|(0xx)2, \ x=(0xx)1|(0xx)1) -- You received this message because you are subscribed to the Google Groups Algorithm Geeks group. To post to this group, send email to algogeeks@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en. -- Mithun.B.S M:9916775380 -- You received this message because you are subscribed to the Google Groups Algorithm Geeks group. To post to this group, send email to algogeeks@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en. -- Regards Rajeev N B http://www.opensourcemania.co.cc *Winners Don't do Different things , they do things Differently* -- You received this message because you are subscribed to the Google Groups Algorithm Geeks group. To post to this group, send email to algogeeks@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
