Function addColorBits

dependency/densecrf/examples/lodepng.cpp:2981–2990

index: bitgroup index, bits: bitgroup size(1, 2 or 4), in: bitgroup value, out: octet array to add bits to*/

/*index: bitgroup index, bits: bitgroup size(1, 2 or 4), in: bitgroup value, out: octet array to add bits to*/
static void addColorBits(unsigned char* out, size_t index, unsigned bits, unsigned in)
{
    unsigned m = bits == 1 ? 7 : bits == 2 ? 3 : 1; /*8 / bits - 1*/
    /*p = the partial index in the byte, e.g. with 4 palettebits it is 0 for first half or 1 for second half*/
    unsigned p = index & m;
    in &= (1u << bits) - 1u; /*filter out any other bits of the input value*/
    in = in << (bits * (m - p));
    if(p == 0) out[index * bits / 8] = in;
    else out[index * bits / 8] |= in;
}

typedef struct ColorTree ColorTree;