STEP_C0           821 third_party/libjpeg/jquant2.c     inc0 = inc0 * (2 * STEP_C0) + STEP_C0 * STEP_C0;
STEP_C0           848 third_party/libjpeg/jquant2.c       xx0 += 2 * STEP_C0 * STEP_C0;