bit_size = s->f_code - 1;
bit_size = f_or_b_code - 1;
static void mpeg1_encode_motion(MpegEncContext *s, int val){    int code, bit_size, l, m, bits, range, sign;    if (val == 0) {        /* zero vector */        code = 0;        put_bits(&s->pb,                 mbMotionVectorTable[0][1],                  mbMotionVectorTable[0][0]);     } else {        bit_size = s->f_code - 1;        range = 1 << bit_size;        /* modulo encoding */        l = 16 * range;        m = 2 * l;        if (val < -l) {            val += m;        } else if (val >= l) {            val -= m;        }        if (val >= 0) {            val--;            code = (val >> bit_size) + 1;            bits = val & (range - 1);            sign = 0;        } else {            val = -val;            val--;            code = (val >> bit_size) + 1;            bits = val & (range - 1);            sign = 1;        }        put_bits(&s->pb,                 mbMotionVectorTable[code][1],                  mbMotionVectorTable[code][0]);         put_bits(&s->pb, 1, sign);        if (bit_size > 0) {            put_bits(&s->pb, bit_size, bits);        }    }}