static int do_write(connection *c) {
    pa_memchunk chunk;
    ssize_t r;
    void *p;

    connection_assert_ref(c);

    if (!c->source_output)
        return 0;

    if (pa_memblockq_peek(c->output_memblockq, &chunk) < 0) {
/*         pa_log("peek failed"); */
        return 0;
    }

    pa_assert(chunk.memblock);
    pa_assert(chunk.length);

    p = pa_memblock_acquire(chunk.memblock);
    r = pa_iochannel_write(c->io, (uint8_t*) p+chunk.index, chunk.length);
    pa_memblock_release(chunk.memblock);

    pa_memblock_unref(chunk.memblock);

    if (r < 0) {
        pa_log("write(): %s", pa_cstrerror(errno));
        return -1;
    }

    pa_memblockq_drop(c->output_memblockq, (size_t) r);

    return 1;
}

void voice_append_chunk_to_file(struct userdata *u, const char *file_name, pa_memchunk *chunk) {
    int i;
    FILE *file = NULL;
    for (i = 0; i < file_table_size && file_table[i].name != NULL; i++) {
        if (0 == strcmp(file_name, file_table[i].name)) {
            file = file_table[i].file;
        }
    }

    if (i >= file_table_size) {
        pa_log("Can't open new files, not writing to file \"%s\"", file_name);
        return;
    }

    if (file == NULL) {
        file = file_table[i].file = fopen(file_name, "w");
        if (file == NULL) {
            pa_log("Can't open file \"%s\": %s", file_name, strerror(errno));
            return;
        }
    }

    char *p = pa_memblock_acquire(chunk->memblock);
    fwrite(p + chunk->index, 1, chunk->length, file);
    pa_memblock_release(chunk->memblock);
}

void pa_memchunk_dump_to_file(pa_memchunk *c, const char *fn) {
    FILE *f;
    void *p;

    pa_assert(c);
    pa_assert(fn);

    /* Only for debugging purposes */

    f = pa_fopen_cloexec(fn, "a");

    if (!f) {
        pa_log_warn("Failed to open '%s': %s", fn, pa_cstrerror(errno));
        return;
    }

    p = pa_memblock_acquire(c->memblock);

    if (fwrite((uint8_t*) p + c->index, 1, c->length, f) != c->length)
        pa_log_warn("Failed to write to '%s': %s", fn, pa_cstrerror(errno));

    pa_memblock_release(c->memblock);

    fclose(f);
}

static int do_read(connection *c) {
    pa_memchunk chunk;
    ssize_t r;
    size_t l;
    void *p;
    size_t space = 0;

    connection_assert_ref(c);

    if (!c->sink_input || (l = (size_t) pa_atomic_load(&c->playback.missing)) <= 0)
        return 0;

    if (c->playback.current_memblock) {

        space = pa_memblock_get_length(c->playback.current_memblock) - c->playback.memblock_index;

        if (space <= 0) {
            pa_memblock_unref(c->playback.current_memblock);
            c->playback.current_memblock = NULL;
        }
    }

    if (!c->playback.current_memblock) {
        pa_assert_se(c->playback.current_memblock = pa_memblock_new(c->protocol->core->mempool, (size_t) -1));
        c->playback.memblock_index = 0;

        space = pa_memblock_get_length(c->playback.current_memblock);
    }

    if (l > space)
        l = space;

    p = pa_memblock_acquire(c->playback.current_memblock);
    r = pa_iochannel_read(c->io, (uint8_t*) p + c->playback.memblock_index, l);
    pa_memblock_release(c->playback.current_memblock);

    if (r <= 0) {

        if (r < 0 && (errno == EINTR || errno == EAGAIN))
            return 0;

        pa_log_debug("read(): %s", r == 0 ? "EOF" : pa_cstrerror(errno));
        return -1;
    }

    chunk.memblock = c->playback.current_memblock;
    chunk.index = c->playback.memblock_index;
    chunk.length = (size_t) r;

    c->playback.memblock_index += (size_t) r;

    pa_asyncmsgq_post(c->sink_input->sink->asyncmsgq, PA_MSGOBJECT(c->sink_input), SINK_INPUT_MESSAGE_POST_DATA, NULL, 0, &chunk, NULL);
    pa_atomic_sub(&c->playback.missing, (int) r);

    return 0;
}

pa_srbchannel* pa_srbchannel_new(pa_mainloop_api *m, pa_mempool *p) {
    int capacity;
    int readfd;
    struct srbheader *srh;

    pa_srbchannel* sr = pa_xmalloc0(sizeof(pa_srbchannel));
    sr->mainloop = m;
    sr->memblock = pa_memblock_new_pool(p, -1);
    if (!sr->memblock)
        goto fail;

    srh = pa_memblock_acquire(sr->memblock);
    pa_zero(*srh);

    sr->rb_read.memory = (uint8_t*) srh + PA_ALIGN(sizeof(*srh));
    srh->readbuf_offset = sr->rb_read.memory - (uint8_t*) srh;

    capacity = (pa_memblock_get_length(sr->memblock) - srh->readbuf_offset) / 2;

    sr->rb_write.memory = PA_ALIGN_PTR(sr->rb_read.memory + capacity);
    srh->writebuf_offset = sr->rb_write.memory - (uint8_t*) srh;

    capacity = PA_MIN(capacity, srh->writebuf_offset - srh->readbuf_offset);

    pa_log_debug("SHM block is %d bytes, ringbuffer capacity is 2 * %d bytes",
        (int) pa_memblock_get_length(sr->memblock), capacity);

    srh->capacity = sr->rb_read.capacity = sr->rb_write.capacity = capacity;

    sr->rb_read.count = &srh->read_count;
    sr->rb_write.count = &srh->write_count;

    sr->sem_read = pa_fdsem_new_shm(&srh->read_semdata);
    if (!sr->sem_read)
        goto fail;

    sr->sem_write = pa_fdsem_new_shm(&srh->write_semdata);
    if (!sr->sem_write)
        goto fail;

    readfd = pa_fdsem_get(sr->sem_read);

#ifdef DEBUG_SRBCHANNEL
    pa_log("Enabling io event on fd %d", readfd);
#endif

    sr->read_event = m->io_new(m, readfd, PA_IO_EVENT_INPUT, semread_cb, sr);
    m->io_enable(sr->read_event, PA_IO_EVENT_INPUT);

    return sr;

fail:
    pa_srbchannel_free(sr);

    return NULL;
}

pa_memchunk* pa_memchunk_memcpy(pa_memchunk *dst, pa_memchunk *src) {
    void *p, *q;

    pa_assert(dst);
    pa_assert(src);
    pa_assert(dst->length == src->length);

    p = pa_memblock_acquire(dst->memblock);
    q = pa_memblock_acquire(src->memblock);

    memmove((uint8_t*) p + dst->index,
            (uint8_t*) q + src->index,
            dst->length);

    pa_memblock_release(dst->memblock);
    pa_memblock_release(src->memblock);

    return dst;
}

static void do_read(struct userdata *u) {
    uint32_t free_frags;
    pa_memchunk memchunk;
    WAVEHDR *hdr;
    MMRESULT res;
    void *p;

    if (!u->source)
        return;

    if (!PA_SOURCE_IS_LINKED(u->source->state))
        return;

    EnterCriticalSection(&u->crit);
    free_frags = u->free_ifrags;
    u->free_ifrags = 0;
    LeaveCriticalSection(&u->crit);

    if (free_frags == u->fragments)
        pa_log_debug("WaveIn overflow!");

    while (free_frags) {
        hdr = &u->ihdrs[u->cur_ihdr];
        if (hdr->dwFlags & WHDR_PREPARED)
            waveInUnprepareHeader(u->hwi, hdr, sizeof(WAVEHDR));

        if (hdr->dwBytesRecorded) {
            memchunk.memblock = pa_memblock_new(u->core->mempool, hdr->dwBytesRecorded);
            pa_assert(memchunk.memblock);

            p = pa_memblock_acquire(memchunk.memblock);
            memcpy((char*) p, hdr->lpData, hdr->dwBytesRecorded);
            pa_memblock_release(memchunk.memblock);

            memchunk.length = hdr->dwBytesRecorded;
            memchunk.index = 0;

            pa_source_post(u->source, &memchunk);
            pa_memblock_unref(memchunk.memblock);
        }

        res = waveInPrepareHeader(u->hwi, hdr, sizeof(WAVEHDR));
        if (res != MMSYSERR_NOERROR)
            pa_log_error("Unable to prepare waveIn block: %d", res);

        res = waveInAddBuffer(u->hwi, hdr, sizeof(WAVEHDR));
        if (res != MMSYSERR_NOERROR)
            pa_log_error("Unable to add waveIn block: %d", res);

        free_frags--;
        u->cur_ihdr++;
        u->cur_ihdr %= u->fragments;
    }
}

/* No lock necessary. */
pa_memblock *pa_memblock_will_need(pa_memblock *b) {
    void *p;

    pa_assert(b);
    pa_assert(PA_REFCNT_VALUE(b) > 0);

    p = pa_memblock_acquire(b);
    pa_will_need(p, b->length);
    pa_memblock_release(b);

    return b;
}

static void dump_chunk(const pa_memchunk *chunk) {
    size_t n;
    void *q;
    char *e;

    pa_assert(chunk);

    q = pa_memblock_acquire(chunk->memblock);
    for (e = (char*) q + chunk->index, n = 0; n < chunk->length; n++, e++)
        fprintf(stderr, "%c", *e);
    pa_memblock_release(chunk->memblock);
}

pa_memblock *pa_silence_memblock(pa_memblock* b, const pa_sample_spec *spec) {
    void *data;

    pa_assert(b);
    pa_assert(spec);

    data = pa_memblock_acquire(b);
    pa_silence_memory(data, pa_memblock_get_length(b), spec);
    pa_memblock_release(b);

    return b;
}

pa_memchunk* pa_silence_memchunk(pa_memchunk *c, const pa_sample_spec *spec) {
    void *data;

    pa_assert(c);
    pa_assert(c->memblock);
    pa_assert(spec);

    data = pa_memblock_acquire(c->memblock);
    pa_silence_memory((uint8_t*) data+c->index, c->length, spec);
    pa_memblock_release(c->memblock);

    return c;
}

static int process_render(struct userdata *u) {
    pa_assert(u);


    if (u->memchunk.length <= 0)
        pa_sink_render(u->sink, ioring->usable_buffer_space, &u->memchunk);


    pa_assert(u->memchunk.length > 0);

    xc_evtchn_notify(xce, xen_evtchn_port);
    for (;;) {
        ssize_t l;
        void *p;

        p = pa_memblock_acquire(u->memchunk.memblock);
	    /* xen: write data to ring buffer & notify backend */
        l = ring_write(ioring, (uint8_t*)p + u->memchunk.index, u->memchunk.length);

        pa_memblock_release(u->memchunk.memblock);

        pa_assert(l != 0);

        if (l < 0) {
            if (errno == EINTR)
                continue;
            else if (errno == EAGAIN)
                return 0;
            else {
                pa_log("Failed to write data to FIFO: %s", pa_cstrerror(errno));
                return -1;
            }

        } else {

            u->memchunk.index += (size_t) l;
            u->memchunk.length -= (size_t) l;

            if (u->memchunk.length <= 0) {
                pa_memblock_unref(u->memchunk.memblock);
                pa_memchunk_reset(&u->memchunk);
            }
        }

        return 0;
    }
}

static int process_sink_render(struct userdata *u)
{
    pa_assert(u);

    if (u->memchunk_sink.length <= 0)
        pa_sink_render(u->sink, libvchan_buffer_space(u->play_ctrl), &u->memchunk_sink);

    pa_assert(u->memchunk_sink.length > 0);

    for (;;) {
        ssize_t l;
        void *p;

        p = pa_memblock_acquire(u->memchunk_sink.memblock);
        l = write_to_vchan(u->play_ctrl, (char *) p +
                           u->memchunk_sink.index, u->memchunk_sink.length);
        pa_memblock_release(u->memchunk_sink.memblock);

        pa_assert(l != 0);

        if (l < 0) {

            if (errno == EINTR)
                continue;
            else if (errno == EAGAIN)
                return 0;
            else {
                pa_log
                ("Failed to write data to VCHAN: %s",
                 pa_cstrerror(errno));
                return -1;
            }

        } else {

            u->memchunk_sink.index += (size_t) l;
            u->memchunk_sink.length -= (size_t) l;

            if (u->memchunk_sink.length <= 0) {
                pa_memblock_unref(u->memchunk_sink.memblock);
                pa_memchunk_reset(&u->memchunk_sink);
            }
        }

        return 0;
    }
}

/* Called from thread context */
static void cmtspeech_source_output_push_cb(pa_source_output *o, const pa_memchunk *chunk) {
    struct userdata *u;
    uint8_t *buf;

    pa_assert(o);
    pa_assert_se(u = o->userdata);

    if (chunk->length != u->ul_frame_size) {
        pa_log_warn("Pushed UL audio frame has wrong size %zu", chunk->length);
        return;
    }

    buf = ((uint8_t *) pa_memblock_acquire(chunk->memblock)) + chunk->index;

    (void)cmtspeech_send_ul_frame(u, buf, chunk->length);

    pa_memblock_release(chunk->memblock);
}

pa_srbchannel* pa_srbchannel_new_from_template(pa_mainloop_api *m, pa_srbchannel_template *t)
{
    int temp;
    struct srbheader *srh;
    pa_srbchannel* sr = pa_xmalloc0(sizeof(pa_srbchannel));

    sr->mainloop = m;
    sr->memblock = t->memblock;
    pa_memblock_ref(sr->memblock);
    srh = pa_memblock_acquire(sr->memblock);

    sr->rb_read.capacity = sr->rb_write.capacity = srh->capacity;
    sr->rb_read.count = &srh->read_count;
    sr->rb_write.count = &srh->write_count;

    sr->rb_read.memory = (uint8_t*) srh + srh->readbuf_offset;
    sr->rb_write.memory = (uint8_t*) srh + srh->writebuf_offset;

    sr->sem_read = pa_fdsem_open_shm(&srh->read_semdata, t->readfd);
    if (!sr->sem_read)
        goto fail;

    sr->sem_write = pa_fdsem_open_shm(&srh->write_semdata, t->writefd);
    if (!sr->sem_write)
        goto fail;

    pa_srbchannel_swap(sr);
    temp = t->readfd; t->readfd = t->writefd; t->writefd = temp;

#ifdef DEBUG_SRBCHANNEL
    pa_log("Enabling io event on fd %d", t->readfd);
#endif

    sr->read_event = m->io_new(m, t->readfd, PA_IO_EVENT_INPUT, semread_cb, sr);
    m->io_enable(sr->read_event, PA_IO_EVENT_INPUT);

    return sr;

fail:
    pa_srbchannel_free(sr);

    return NULL;
}

static int process_render(struct userdata *u) {
    pa_assert(u);

    if (u->memchunk.length <= 0)
        pa_sink_render(u->sink, u->buffer_size, &u->memchunk);

    pa_assert(u->memchunk.length > 0);

    for (;;) {
        ssize_t l;
        void *p;

        p = pa_memblock_acquire(u->memchunk.memblock);
        l = pa_write(u->fd, (uint8_t*) p + u->memchunk.index, u->memchunk.length, &u->write_type);
        pa_memblock_release(u->memchunk.memblock);

        pa_assert(l != 0);

        if (l < 0) {

            if (errno == EINTR)
                continue;
            else if (errno == EAGAIN)
                return 0;
            else {
                pa_log("Failed to write data to FIFO: %s", pa_cstrerror(errno));
                return -1;
            }

        } else {

            u->memchunk.index += (size_t) l;
            u->memchunk.length -= (size_t) l;

            if (u->memchunk.length <= 0) {
                pa_memblock_unref(u->memchunk.memblock);
                pa_memchunk_reset(&u->memchunk);
            }
        }

        return 0;
    }
}

static void dump(pa_memblockq *bq) {
    printf(">");

    for (;;) {
        pa_memchunk out;
        char *e;
        size_t n;
        void *q;

        if (pa_memblockq_peek(bq, &out) < 0)
            break;

        q = pa_memblock_acquire(out.memblock);
        for (e = (char*) q + out.index, n = 0; n < out.length; n++)
            printf("%c", *e);
        pa_memblock_release(out.memblock);

        pa_memblock_unref(out.memblock);
        pa_memblockq_drop(bq, out.length);
    }

    printf("<\n");
}

void pa_memchunk_sine(pa_memchunk *c, pa_mempool *pool, unsigned rate, unsigned freq) {
    size_t l;
    unsigned gcd, n;
    void *p;

    pa_memchunk_reset(c);

    gcd = pa_gcd(rate, freq);
    n = rate / gcd;

    l = pa_mempool_block_size_max(pool) / sizeof(float);

    l /= n;
    if (l <= 0) l = 1;
    l *= n;

    c->length = l * sizeof(float);
    c->memblock = pa_memblock_new(pool, c->length);

    p = pa_memblock_acquire(c->memblock);
    calc_sine(p, c->length, freq * l / rate);
    pa_memblock_release(c->memblock);
}

static int sink_process_msg(pa_msgobject *o, int code, void *data, int64_t offset, pa_memchunk *memchunk) {
    struct userdata *u = PA_SINK(o)->userdata;

    switch (code) {

        case SINK_MESSAGE_RENDER:

            /* Handle the request from the JACK thread */

            if (u->sink->thread_info.state == PA_SINK_RUNNING) {
                pa_memchunk chunk;
                size_t nbytes;
                void *p;

                pa_assert(offset > 0);
                nbytes = (size_t) offset * pa_frame_size(&u->sink->sample_spec);

                pa_sink_render_full(u->sink, nbytes, &chunk);

                p = (uint8_t*) pa_memblock_acquire(chunk.memblock) + chunk.index;
                pa_deinterleave(p, u->buffer, u->channels, sizeof(float), (unsigned) offset);
                pa_memblock_release(chunk.memblock);

                pa_memblock_unref(chunk.memblock);
            } else {
                unsigned c;
                pa_sample_spec ss;

                /* Humm, we're not RUNNING, hence let's write some silence */

                ss = u->sink->sample_spec;
                ss.channels = 1;

                for (c = 0; c < u->channels; c++)
                    pa_silence_memory(u->buffer[c], (size_t) offset * pa_sample_size(&ss), &ss);
            }

            u->frames_in_buffer = (jack_nframes_t) offset;
            u->saved_frame_time = * (jack_nframes_t*) data;
            u->saved_frame_time_valid = TRUE;

            return 0;

        case SINK_MESSAGE_BUFFER_SIZE:
            pa_sink_set_max_request_within_thread(u->sink, (size_t) offset * pa_frame_size(&u->sink->sample_spec));
            return 0;

        case SINK_MESSAGE_ON_SHUTDOWN:
            pa_asyncmsgq_post(u->thread_mq.outq, PA_MSGOBJECT(u->core), PA_CORE_MESSAGE_UNLOAD_MODULE, u->module, 0, NULL, NULL);
            return 0;

        case PA_SINK_MESSAGE_GET_LATENCY: {
            jack_nframes_t l, ft, d;
            size_t n;

            /* This is the "worst-case" latency */
            l = jack_port_get_total_latency(u->client, u->port[0]) + u->frames_in_buffer;

            if (u->saved_frame_time_valid) {
                /* Adjust the worst case latency by the time that
                 * passed since we last handed data to JACK */

                ft = jack_frame_time(u->client);
                d = ft > u->saved_frame_time ? ft - u->saved_frame_time : 0;
                l = l > d ? l - d : 0;
            }

            /* Convert it to usec */
            n = l * pa_frame_size(&u->sink->sample_spec);
            *((pa_usec_t*) data) = pa_bytes_to_usec(n, &u->sink->sample_spec);

            return 0;
        }

    }

    return pa_sink_process_msg(o, code, data, offset, memchunk);
}

int pa_sound_file_load(
        pa_mempool *pool,
        const char *fname,
        pa_sample_spec *ss,
        pa_channel_map *map,
        pa_memchunk *chunk,
        pa_proplist *p) {

    SNDFILE *sf = NULL;
    SF_INFO sfi;
    int ret = -1;
    size_t l;
    sf_count_t (*readf_function)(SNDFILE *sndfile, void *ptr, sf_count_t frames) = NULL;
    void *ptr = NULL;
    int fd;

    pa_assert(fname);
    pa_assert(ss);
    pa_assert(chunk);

    pa_memchunk_reset(chunk);

    if ((fd = pa_open_cloexec(fname, O_RDONLY, 0)) < 0) {
        pa_log("Failed to open file %s: %s", fname, pa_cstrerror(errno));
        goto finish;
    }

#ifdef HAVE_POSIX_FADVISE
    if (posix_fadvise(fd, 0, 0, POSIX_FADV_SEQUENTIAL) < 0) {
        pa_log_warn("POSIX_FADV_SEQUENTIAL failed: %s", pa_cstrerror(errno));
        goto finish;
    } else
        pa_log_debug("POSIX_FADV_SEQUENTIAL succeeded.");
#endif

    pa_zero(sfi);
    if (!(sf = sf_open_fd(fd, SFM_READ, &sfi, 1))) {
        pa_log("Failed to open file %s", fname);
        goto finish;
    }

    fd = -1;

    if (pa_sndfile_read_sample_spec(sf, ss) < 0) {
        pa_log("Failed to determine file sample format.");
        goto finish;
    }

    if ((map && pa_sndfile_read_channel_map(sf, map) < 0)) {
        if (ss->channels > 2)
            pa_log("Failed to determine file channel map, synthesizing one.");
        pa_channel_map_init_extend(map, ss->channels, PA_CHANNEL_MAP_DEFAULT);
    }

    if (p)
        pa_sndfile_init_proplist(sf, p);

    if ((l = pa_frame_size(ss) * (size_t) sfi.frames) > PA_SCACHE_ENTRY_SIZE_MAX) {
        pa_log("File too large");
        goto finish;
    }

    chunk->memblock = pa_memblock_new(pool, l);
    chunk->index = 0;
    chunk->length = l;

    readf_function = pa_sndfile_readf_function(ss);

    ptr = pa_memblock_acquire(chunk->memblock);

    if ((readf_function && readf_function(sf, ptr, sfi.frames) != sfi.frames) ||
        (!readf_function && sf_read_raw(sf, ptr, (sf_count_t) l) != (sf_count_t) l)) {
        pa_log("Premature file end");
        goto finish;
    }

    ret = 0;

finish:

    if (sf)
        sf_close(sf);

    if (ptr)
        pa_memblock_release(chunk->memblock);

    if (ret != 0 && chunk->memblock)
        pa_memblock_unref(chunk->memblock);

    if (fd >= 0)
        pa_close(fd);

    return ret;
}