Fold larger bitmap into smaller, modulo specified size
void bitmap_fold(unsigned long * dst, const unsigned long * orig, int sz, int bits);
dst
resulting smaller bitmap
orig
original larger bitmap
sz
specified size
bits
number of bits in each of these bitmaps
For each bit oldbit in orig, set bit oldbit mod sz in dst. Clear all other bits in dst. See further the comment and Example [2] for bitmap_onto for why and how to use this.