gistfile1.c

void encode(void)
{
    ...
    while (r < bufferend) {
        ...
        r += y; s += y;
        if (r >= N * 2 - F) {
            for (i = 0; i < N; i++) buffer[i] = buffer[i + N];
            bufferend -= N;  r -= N;  s -= N;
            while (bufferend < N * 2) {
                if ((c = fgetc(infile)) == EOF) break;
                buffer[bufferend++] = c;  textcount++;
            }
        }
    }
    ...
}