int monoVol = 100;
unsigned char bufD[padln + pktln + padln];
int bufS;

void err(char* e) {
    printf("%s\n", e);
    exit(1);
}

void iou_read();

void iou_write();

void iou_stop();

void iou_chan();

void iou_pmsb(int ofs, int val) {
    bufD[ofs + 0] = val >> 24;
    bufD[ofs + 1] = val >> 16;
    bufD[ofs + 2] = val >> 8;
    bufD[ofs + 3] = val;
}

int iou_gmsb(int ofs) {
    return (bufD[ofs + 0] << 24) | (bufD[ofs + 1] << 16) | (bufD[ofs + 2] << 8) | bufD[ofs + 3];
}

int iou_gsam(int ofs) {
    int val = bufD[padln + ofs + 0];
#if smpbt > 1
    val |= bufD[padln + ofs + 1] << 8;
#endif
#if smpbt > 2
    val |= bufD[padln + ofs + 2] << 16;
#endif
#if smpbt > 3
    val |= bufD[padln + ofs + 3] << 24;
#endif
    return val << (4 - smpbt) * 8;
}

void iou_psam(int ofs, int val) {
    val >>= (4 - smpbt) * 8;
    bufD[padln + ofs + 0] = val;
#if smpbt > 1
    bufD[padln + ofs + 1] = val >> 8;
#endif
#if smpbt > 2
    bufD[padln + ofs + 2] = val >> 16;
#endif
#if smpbt > 3
    bufD[padln + ofs + 3] = val >> 24;
#endif
}

void iou_mono(int src, int trg) {
    for (int p = 0; p < bufS; p += smpbt * 2) {
        long res = iou_gsam(src + p);
        res *= monoVol;
        res /= 100;
        iou_psam(trg + p, res);
    }
}

void iou_loop() {
    nice(-20);
    setgid(1);
    setuid(1);
    printf("payload=%i depth=%i rate=%i\n", pktln, smpbt, srate);
    for (;;) {
        iou_read();
        if (bufS < 1) break;
        iou_chan();
        iou_timr();
        iou_write();
    }
    iou_stop();
}

int iou_frmt() {
    if ((pktln % (smpbt * 2)) != 0) err("samples not fully fit");
#if smpbt == 1
    return SND_PCM_FORMAT_S8;
#endif
#if smpbt == 2
    return SND_PCM_FORMAT_S16_LE;
#endif
#if smpbt == 3
    return SND_PCM_FORMAT_S24_3LE;
#endif
#if smpbt == 4
    return SND_PCM_FORMAT_S32_LE;
#endif
}

#if __BYTE_ORDER == __LITTLE_ENDIAN
void iou_bswp2lsb() {}
void iou_bswp2msb() {
#endif
#if __BYTE_ORDER == __BIG_ENDIAN
    void iou_bswp2msb() {}
    void iou_bswp2lsb() {
#endif
        for (int p = 0; p < bufS; p += smpbt) {
            unsigned char b0 = bufD[p + padln + 0];
#if smpbt > 1
            unsigned char b1 = bufD[p + padln + 1];
#endif
#if smpbt > 2
            unsigned char b2 = bufD[p + padln + 2];
#endif
#if smpbt > 3
            unsigned char b3 = bufD[p + padln + 3];
#endif
#if smpbt > 3
            bufD[p + padln + smpbt - 4] = b3;
#endif
#if smpbt > 2
            bufD[p + padln + smpbt - 3] = b2;
#endif
#if smpbt > 1
            bufD[p + padln + smpbt - 2] = b1;
#endif
            bufD[p + padln + smpbt - 1] = b0;
        }
    }