static void write40_skip(byte*& w, int count)
{
while (count)
{
if (count < 0x80)
{
write40_c5(w, count);
count = 0;
}
else
{
int c_write = count < 0x8000 ? count : 0x7fff;
write40_c2(w, c_write);
count -= c_write;
}
}
}
int encode40(const byte* last_s, const byte* x, byte* d, int cb_s)
{
// full compression
byte* s = new byte[cb_s];
{
byte* a = s;
int size = cb_s;
while (size--)
*a++ = *last_s++ ^ *x++;
}
const byte* s_end = s + cb_s;
const byte* r = s;
byte* w = d;
const byte* copy_from = NULL;
while (r < s_end)
{
int v = *r;
int t = get_run_length(r, s_end);
if (!v)
{
flush_copy(w, r, copy_from);
write40_skip(w, t);
}
else if (t > 2)
{
flush_copy(w, r, copy_from);
write40_fill(w, t, v);
}
else
{
if (!copy_from)
copy_from = r;
}
r += t;
}
flush_copy(w, r, copy_from);
write40_c2(w, 0);
delete[] s;
return w - d;
}