include c:\cxpl\codes;  \intrinsic 'code' declarations
string 0;               \use zero-terminated strings, instead of MSb terminated

proc Compress(S);       \Compress string using run-length encoding, & display it
char S;
int  I, C0, C, N;
[I:= 0;
C0:= S(I);  I:= I+1;
repeat  ChOut(0, C0);
        N:= 0;
        repeat  C:= S(I);  I:= I+1;
                N:= N+1;
        until   C#C0;
        if N>1 then IntOut(0, N-1);
        C0:= C;
until   C=0;
]; \Compress

proc Expand(S);         \Expand compressed string, and display it
char S;
int  I, C0, C, N;
[I:= 0;
C0:= S(I);  I:= I+1;
repeat  ChOut(0, C0);
        C:= S(I);  I:= I+1;
        if C>=^1 & C<=^9 then
                [N:= 0;
                while C>=^0 & C<=^9 do
                        [N:= N*10 + C-^0;
                        C:= S(I);  I:= I+1;
                        ];
                while N do [ChOut(0, C0);  N:= N-1];
                ];
        C0:= C;
until   C=0;
]; \Expand

[Compress("WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW");
CrLf(0);
Expand("W11BW11B2W23BW13");  CrLf(0);
]