Canonicalize CIDR: Difference between revisions

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parse arg z . /*obtain optional argument from the CL.*/

if z=='' | z=="," then z= '87.70.141.1/22' /*Not specified? Then use the default.*/

parse var z # '/' -0 mask /*get the address nodes & ~~optional~~ mask*/

parse var z # '/' -0 mask /*get the address nodes & netaddr mask.*/

size= d2b( substr(mask, 2) ) /*size of binary network mask in bytes.*/

shift= length(size % 2**8) /*compute the size of the binary shift.*/

#= translate(#, , .) /*elide periods from IPv4 address nodes*/

$= /*initialize the to-be reassembled IPv4*/

do j=1 for words(#); x= ~~word(#,~~ j) /*process each of ~~the~~ ~~address~~ ~~nodes.~~ */

do j=1 for max( words(#), 4) /*process each of IP node, a min of 4. */

if ~~j>1~~ & ~~x//2~~ ~~then~~ x= x ~~- 1~~ /*Is ~~low─order~~ ~~bit~~ ~~on?~~ ~~Then~~ ~~remove~~ ~~it.~~*/

x= word( word(#, j) 0, 1) /*use a zero for omitted IP nodes. */

if j>shift then do /*possibly elide some low─order bits. */

_= right( d2b(x), 2**5, 0) /*convert X to binary, pad with zeros.*/

x= b2d( (left(_, length(_)-shift) || left('', shift, 0) ) )

end /* [↑] "zero─out" some low─order bits*/

$= $ x /*reconstruct (by abutment) IPv4 nodes.*/

end /*j*/ /*(REXX stores it's numbers in decimal)*/

/*~~stick a fork~~ in ~~it,~~ ~~we're~~ ~~all~~ ~~done.~~ */

say ' original IPv4 address: ' z /*display the original IPv4 address. */

say ' canonicalized address: ' translate( space($), ., " ") || ~~mask~~ /*canonicalized.*/~~</lang>~~

say ' canonicalized address: ' translate( space($), ., " ")mask /*canonicalized.*/

exit 0 /*stick a fork in it, we're all done. */

/*──────────────────────────────────────────────────────────────────────────────────────*/

b2d: return x2d( b2x( arg(1) ) ) + 0 /*convert binary ───► decimal number.*/

d2b: return x2b( d2x( arg(1) ) ) + 0 /* " decimal ───► binary " */</lang>

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