Challenge and origin

On Stack Overflow a popular question is: How to convert byte size into human readable format in java? The most up voted answer has a quite nice method for doing this, but this is codegolf and we can do better, can't we?

Your challenge is to write a method or program that coverts the given number of bytes to the correct human readable format and prints the result to the standard out of your language.*

_{*See the rules for more clarification!}

Input

The input will always be a positive number of bytes with a maximum of (2^31)-1.

Output

You may choose if you prefer the International System of Units or the binary notation as output (the SI notation probably saves you some bytes).

SI:      B, kB,  MB,  GB  
Binary:  B, KiB, MiB, GiB

_{Note: Higher units than GB or GiB are not posible due to the restricted input range.}

Example output

International System of Units:

Input       Output
0           0       B
999         999     B
1000        1.0     kB
1023        1.0     kB
1024        1.0     kB
1601        1.6     kB
160581      160.6   kB
4066888     4.1     MB
634000000   634.0   MB
2147483647  2.1     GB

Binary:

Input       Output
0           0       B
999         999     B
1000        1000    B
1023        1023    B
1024        1.0     KiB
1601        1.6     KiB
160581      156.8   KiB
4066888     3.9     MiB
634000000   604.6   MiB
2147483647  2.0     GiB

Rules

• Build-in functions for byte formatting are not allowed!
• The output should always be in the same notation standard, you may not mix SI or binary;
• The output should always be in the largest unit possible where the resulting number is still higher or equal to one;
• The output should always have one decimal number, but you may choose to print an integer number when the resulting output is in bytes (B);
• You may choose if you would like to add a space, tab or nothing between the number and the unit;
• Input is received via STDIN or function parameters;
• Output is printed to the console or returned as string (or similar character container);
• This is code golf, so the shortest answer wins. Have fun!