that time i forgot C

while(*dp) { *dp -= 1; *(dp + offset) += factor; }

// is not the same as; top works, bottom doesn't

*(dp + offset) += *dp * factor;
*dp = 0;

// neither does this:

u64 a = 0;
while(*dp) { *dp -= 1; a += factor; }
*(dp + offset) += a;

// i chose u64 in case it overflows a u8
// u8 doesn't work either

// the top one must work because it handles overflows differently than the other two...