c_1
p_b = SCALE_MUL((int64_t)fs->c_1, (int64_t)q->avg) - fs->c_2;
u_int c_1 ; /* max_p/(max_th-min_th) (scaled) */
fs->c_1 = fs->max_p;
fs->c_1 = SCALE((int64_t)(fs->max_p)) / (fs->fs.max_th - fs->fs.min_th);
fs->c_2 = SCALE_MUL(fs->c_1, SCALE(fs->fs.min_th));