Gray code: Difference between revisions
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31 11111 10000 11111
</pre>
=={{header|SparForte}}==
As a structured script.
<syntaxhighlight lang="ada">#!/usr/local/bin/spar
pragma annotate( summary, "gray" );
pragma annotate( description, "Gray code is a form of binary encoding where " );
pragma annotate( description, "transitions between consecutive numbers differ by" );
pragma annotate( description, "only one bit. Create functions to encode a number" );
pragma annotate( description, "to and decode a number from Gray code. Display the" );
pragma annotate( description, "normal binary representations, Gray code" );
pragma annotate( description, "representations, and decoded Gray code values for all" );
pragma annotate( description, "5-bit binary numbers (0-31 inclusive, leading 0's not" );
pragma annotate( description, "necessary). There are many possible Gray codes. The" );
pragma annotate( description, "following encodes what is called 'binary reflected" );
pragma annotate( description, "Gray code.'" );
pragma annotate( see_also, "http://rosettacode.org/wiki/Gray_code" );
pragma annotate( author, "Ken O. Burtch" );
pragma license( unrestricted );
pragma restriction( no_external_commands );
procedure gray is
bits : constant natural := 5;
subtype nat_values is natural;
function encode (binary : nat_values) return nat_values is
begin
return binary xor numerics.shift_right (binary, 1);
end encode;
-- SparForte 1.3 cannot print to numbers to different bases but we
-- we can write a function
function intToBin( nat_value : nat_values ) return string is
result : string;
v : nat_values := nat_value;
begin
if v = 0 then
result := '0';
else
while v > 0 loop
if (v and 1) = 1 then
result := '1' & @;
else
result := '0' & @;
end if;
v := numerics.shift_right( @, 1 );
end loop;
end if;
return "2#" & result & "#";
end intToBin;
function decode (gray : nat_values) return nat_values is
binary : nat_values;
bit : nat_values;
mask : nat_values := 2 ** (bits - 1);
begin
bit := gray and mask;
binary := bit;
for i in 2 .. bits loop
bit := numerics.shift_right (@, 1);
mask := numerics.shift_right (mask, 1);
bit := (gray and mask) xor @;
binary := @ + bit;
end loop;
return binary;
end decode;
j : nat_values;
ibinstr : string;
jbinstr : string;
begin
put_line ("Number Binary Gray Decoded");
for i in 0..31 loop
j := encode (i);
-- convert i and j to base 2 representation
ibinstr := intToBin(i);
jbinstr := intToBin(j);
-- for binary strings, right-justify
put (i, "ZZZZZ9" ) @
(' ' & strings.insert( ibinstr, 1, (8-strings.length(ibinstr)) * ' ' ) ) @
(' ' & strings.insert( jbinstr, 1, (8-strings.length(jbinstr)) * ' ' ) ) @
( " " ) @ (decode (j), "ZZZZZ9" );
new_line;
end loop;
end gray;</syntaxhighlight>
=={{header|SQL}}==
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