vbi.cpp

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// POSIX headers
#include <unistd.h>
#include <fcntl.h>
 
#include <sys/ioctl.h>
 
// ANSI C++ headers
#include <cmath>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
 
#ifdef USING_V4L2
#include <linux/videodev2.h>
#endif // USING_V4L2
 
// vbitext headers
#include "captions/vbilut.h"
#include "vbi.h"
#include "vt.h"
 
#define FAC    (1<<16)         // factor for fix-point arithmetic
 
static unsigned char *rawbuf = nullptr;// one common buffer for raw vbi data.
#ifdef USING_V4L2
static int rawbuf_size;                // its current size
#endif // USING_V4L2
 
/***** bttv api *****/
#define BTTV_VBISIZE           _IOR('v' , BASE_VIDIOCPRIVATE+8, int)
 
 
static void
error(const char *str, ...)
{
    va_list ap;
 
    va_start(ap, str);
    vfprintf(stderr, str, ap);
    fprintf(stderr, "\n");
    va_end(ap);
}
 
 
static int
chk_parity(uint8_t *p, int n)
{
    int err = 0;
 
    for (err = 0; n--; p++)
    {
       if (hamm24par[0][*p] & 32)
           *p &= 0x7f;
       else
           *p = BAD_CHAR, err++;
    }
    return err;
}
 
static void
out_of_sync(struct vbi *vbi)
{
    int i = 0;
 
    // discard all in progress pages
    for (i = 0; i < 8; ++i)
       vbi->rpage[i].page->flags &= ~PG_ACTIVE;
}
 
 
// send an event to all clients
 
static void
vbi_send(struct vbi *vbi, int type, int i1, int i2, int i3, void *p1)
{
    struct vt_event ev {};
    struct vbi_client *cl = nullptr;
    struct vbi_client *cln = nullptr;
 
    ev.resource = vbi;
    ev.type = type;
    ev.i1 = i1;
    ev.i2 = i2;
    ev.i3 = i3;
    ev.p1 = p1;
 
    for (cl = static_cast<vbi_client *>((void*)vbi->clients[0].first);
         (cln = static_cast<vbi_client *>((void*)cl->node->next)) != nullptr;
         cl = cln)
       cl->handler(cl->data, &ev);
}
 
static void
vbi_send_page(struct vbi *vbi, struct raw_page *rvtp, int page)
{
    if (rvtp->page->flags & PG_ACTIVE)
    {
       if (rvtp->page->pgno % 256 != page)
       {
           struct vt_page *cvtp = nullptr;
           rvtp->page->flags &= ~PG_ACTIVE;
           do_enhancements(rvtp->enh, rvtp->page);
//         if (vbi->cache)
//             cvtp = vbi->cache->op->put(vbi->cache, rvtp->page);
           vbi_send(vbi, EV_PAGE, 0, 0, 0, cvtp ?: rvtp->page);
       }
    }
}
 
// fine tune pll
// this routines tries to adjust the sampling point of the decoder.
// it collects parity and hamming errors and moves the sampling point
// a 10th of a bitlength left or right.
 
static constexpr int8_t PLL_SAMPLES  { 4 };  // number of err vals to collect
static constexpr int8_t PLL_ERROR    { 4 };  // if this err val is crossed, readjust
//static constexpr int8_t PLL_ADJUST { 4 };  // max/min adjust (10th of bitlength)
 
static void
pll_add(struct vbi *vbi, int n, int err)
{
    if (vbi->pll_fixed)
       return;
 
    if (err > PLL_ERROR*2/3)   // limit burst errors
       err = PLL_ERROR*2/3;
 
    vbi->pll_err += err;
    vbi->pll_cnt += n;
    if (vbi->pll_cnt < PLL_SAMPLES)
       return;
 
    if (vbi->pll_err > PLL_ERROR)
    {
       if (vbi->pll_err > vbi->pll_lerr)
           vbi->pll_dir = -vbi->pll_dir;
       vbi->pll_lerr = vbi->pll_err;
 
       vbi->pll_adj += vbi->pll_dir;
       if (vbi->pll_adj < -PLL_ADJUST || vbi->pll_adj > PLL_ADJUST)
       {
           vbi->pll_adj = 0;
           vbi->pll_dir = -1;
           vbi->pll_lerr = 0;
       }
 
#ifdef DEBUG
           printf("pll_adj = %2d\n", vbi->pll_adj);
#endif
    }
    vbi->pll_cnt = 0;
    vbi->pll_err = 0;
}
 
void
vbi_pll_reset(struct vbi *vbi, int fine_tune)
{
    vbi->pll_fixed = static_cast<int>(fine_tune >= -PLL_ADJUST && fine_tune <= PLL_ADJUST);
 
    vbi->pll_err = 0;
    vbi->pll_lerr = 0;
    vbi->pll_cnt = 0;
    vbi->pll_dir = -1;
    vbi->pll_adj = 0;
    if (vbi->pll_fixed)
       vbi->pll_adj = fine_tune;
#ifdef DEBUG
       if (vbi->pll_fixed)
           printf("pll_reset (fixed@%d)\n", vbi->pll_adj);
       else
           printf("pll_reset (auto)\n");
#endif
}
 
// process one videotext packet
 
static int
vt_line(struct vbi *vbi, unsigned char *p)
{
    struct vt_page *cvtp = nullptr;
    struct raw_page *rvtp = nullptr;
    int err = 0;
 
    int hdr = hamm16(p, &err);
    if (err & 0xf000)
       return -4;
 
    int mag = hdr & 7;
    int mag8 = mag?: 8;
    int pkt = (hdr >> 3) & 0x1f;
    p += 2;
 
    rvtp = vbi->rpage + mag;
    cvtp = rvtp->page;
 
    switch (pkt)
    {
       case 0:
       {
           int b1 = hamm16(p, &err);       // page number
           int b2 = hamm16(p+2, &err);     // subpage number + flags
           int b3 = hamm16(p+4, &err);     // subpage number + flags
           int b4 = hamm16(p+6, &err);     // language code + more flags
 
           if (vbi->ppage->page->flags & PG_MAGSERIAL)
               vbi_send_page(vbi, vbi->ppage, b1);
           vbi_send_page(vbi, rvtp, b1);
 
           if (err & 0xf000)
               return 4;
 
           cvtp->errors = (err >> 8) + chk_parity(p + 8, 32);;
           cvtp->pgno = mag8 * 256 + b1;
           cvtp->subno = (b2 + b3 * 256) & 0x3f7f;
           cvtp->lang = "\0\4\2\6\1\5\3\7"[b4 >> 5] + (isLatin1 ? 0 : 8);
           cvtp->flags = b4 & 0x1f;
           cvtp->flags |= b3 & 0xc0;
           cvtp->flags |= (b2 & 0x80) >> 2;
           cvtp->lines = 1;
           cvtp->flof = 0;
           vbi->ppage = rvtp;
 
           pll_add(vbi, 1, cvtp->errors);
 
           conv2latin(p + 8, 32, cvtp->lang);
           vbi_send(vbi, EV_HEADER, cvtp->pgno, cvtp->subno, cvtp->flags, p);
 
           if (b1 == 0xff)
               return 0;
 
           cvtp->flags |= PG_ACTIVE;
           init_enhance(rvtp->enh);
           memcpy(cvtp->data[0]+0, p, 40);
           memset(cvtp->data[0]+40, ' ', sizeof(cvtp->data)-40);
           return 0;
       }
 
       case 1 ... 24:
       {
           pll_add(vbi, 1, err = chk_parity(p, 40));
 
           if (~cvtp->flags & PG_ACTIVE)
               return 0;
 
           cvtp->errors += err;
           cvtp->lines |= 1 << pkt;
           conv2latin(p, 40, cvtp->lang);
           memcpy(cvtp->data[pkt], p, 40);
           return 0;
       }
       case 26:
       {
           if (~cvtp->flags & PG_ACTIVE)
               return 0;
 
           int d = hamm8(p, &err);
           if (err & 0xf000)
               return 4;
 
           std::array<unsigned int,13> t {};
           for (ptrdiff_t i = 0; i < 13; ++i)
               t[i] = hamm24(p + 1 + 3*i, &err);
           if (err & 0xf000)
               return 4;
 
           //printf("enhance on %x/%x\n", cvtp->pgno, cvtp->subno);
           add_enhance(rvtp->enh, d, t);
           return 0;
       }
       case 27:
       {
           // FLOF data (FastText)
           if (~cvtp->flags & PG_ACTIVE)
               return 0; // -1 flushes all pages.  we may never resync again :(
 
           int b1 = hamm8(p, &err);
           int b2 = hamm8(p + 37, &err);
           if (err & 0xf000)
               return 4;
           if (b1 != 0 || !(b2 & 8))
               return 0;
 
           for (ptrdiff_t i = 0; i < 6; ++i)
           {
               err = 0;
               b1 = hamm16(p+1+6*i, &err);
               b2 = hamm16(p+3+6*i, &err);
               int b3 = hamm16(p+5+6*i, &err);
               if (err & 0xf000)
                   return 1;
               int x = (b2 >> 7) | ((b3 >> 5) & 0x06);
               cvtp->link[i].pgno = ((mag ^ x) ?: 8) * 256 + b1;
               cvtp->link[i].subno = (b2 + b3 * 256) & 0x3f7f;
           }
           cvtp->flof = 1;
           return 0;
       }
       case 30:
       {
           if (mag8 != 8)
               return 0;
 
           p[0] = hamm8(p, &err);              // designation code
           p[1] = hamm16(p+1, &err);           // initial page
           p[3] = hamm16(p+3, &err);           // initial subpage + mag
           p[5] = hamm16(p+5, &err);           // initial subpage + mag
           if (err & 0xf000)
               return 4;
 
           err += chk_parity(p+20, 20);
           conv2latin(p+20, 20, 0);
 
           vbi_send(vbi, EV_XPACKET, mag8, pkt, err, p);
           return 0;
       }
       default:
           // unused at the moment...
           //vbi_send(vbi, EV_XPACKET, mag8, pkt, err, p);
           return 0;
    }
    return 0;
}
 
 
 
// process one raw vbi line
 
static int
vbi_line(struct vbi *vbi, const unsigned char *p)
{
    std::array<unsigned char,43> data {};
    std::array<int,2566> dt {};
    std::array<int,6>    hi {};
    std::array<int,6>    lo {};
    int i = 0;
    int n = 0;
    int bpb = vbi->bpb;
 
    /* remove DC. edge-detector */
    for (i = vbi->soc; i < vbi->eoc; ++i)
       dt[i] = p[i+bpb/FAC] - p[i];    // amplifies the edges best.
 
    /* set barrier */
    for (i = vbi->eoc; i < vbi->eoc+16; i += 2)
       dt[i] = 100, dt[i+1] = -100;
 
    /* find 6 rising and falling edges */
    for (i = vbi->soc, n = 0; n < 6; ++n)
    {
       while (dt[i] < 32)
           i++;
       hi[n] = i;
       while (dt[i] > -32)
           i++;
       lo[n] = i;
    }
    if (i >= vbi->eoc)
       return -1;      // not enough periods found
 
    i = hi[5] - hi[1]; // length of 4 periods (8 bits)
    if (i < vbi->bp8bl || i > vbi->bp8bh)
       return -1;      // bad frequency
 
    /* AGC and sync-reference */
    unsigned char min = 255;
    unsigned char max = 0;
    int sync = 0;
    for (i = hi[4]; i < hi[5]; ++i)
       if (p[i] > max)
           max = p[i], sync = i;
    for (i = lo[4]; i < lo[5]; ++i)
       if (p[i] < min)
           min = p[i];
    int thr = (min + max) / 2;
 
    p += sync;
 
    /* search start-byte 11100100 */
    for (i = 4*bpb + vbi->pll_adj*bpb/10; i < 16*bpb; i += bpb)
    {
       if (p[i/FAC] > thr && p[(i+bpb)/FAC] > thr) // two ones is enough...
       {
           /* got it... */
           data.fill(0);
 
           for (n = 0; n < 43*8; ++n, i += bpb)
               if (p[i/FAC] > thr)
                   data[n/8] |= 1 << (n%8);
 
           if (data[0] != 0x27)        // really 11100100? (rev order!)
               return -1;
 
           if ((i = vt_line(vbi, data.data()+1)))
           {
               if (i < 0)
                   pll_add(vbi, 2, -i);
               else
                   pll_add(vbi, 1, i);
           }
           return 0;
       }
    }
    return -1;
}
 
 
 
// called when new vbi data is waiting
 
void
vbi_handler(struct vbi *vbi, [[maybe_unused]] int fd)
{
    int n = 0;
    unsigned int seq = 0;
 
    n = read(vbi->fd, rawbuf, vbi->bufsize);
 
    if (dl_empty(vbi->clients))
       return;
 
    if (n != vbi->bufsize)
       return;
 
    seq = *(unsigned int *)&rawbuf[n - 4];
    if (vbi->seq+1 != seq)
    {
       out_of_sync(vbi);
       if (seq < 3 && vbi->seq >= 3)
           vbi_reset(vbi);
    }
    vbi->seq = seq;
 
    if (seq > 1)       // the first may contain data from prev channel
    {
#if 1
       for (int i = 0; i+vbi->bpl <= n; i += vbi->bpl)
           vbi_line(vbi, rawbuf + i);
#else
        /* work-around for old saa7134 driver versions (prior 0.2.6) */
       for (int i = 16 * vbi->bpl; i + vbi->bpl <= n; i += vbi->bpl)
           vbi_line(vbi, rawbuf + i);
 
       for (int i = 0; i + vbi->bpl <= 16 * vbi->bpl; i += vbi->bpl)
           vbi_line(vbi, rawbuf + i);
#endif
    }
}
 
 
 
int
vbi_add_handler(struct vbi *vbi, vbic_handler handler, void *data)
{
    struct vbi_client *cl = nullptr;
 
    if (!(cl = new struct vbi_client))
       return -1;
    cl->handler = handler;
    cl->data = data;
    // cl is not leaking, the first struct element has the same address
    // as the struct
    dl_insert_last(vbi->clients, cl->node);
    return 0; // cppcheck-suppress memleak
}
 
 
 
void
vbi_del_handler(struct vbi *vbi, vbic_handler handler, void *data)
{
    struct vbi_client *cl = nullptr;
 
    for (cl = static_cast<vbi_client*>((void*)vbi->clients->first);
         cl->node->next != nullptr;
         cl = static_cast<vbi_client*>((void*)cl->node->next))
    {
       if (cl->handler == handler && cl->data == data)
       {
           dl_remove(cl->node);
           delete cl;
           break;
       }
    }
}
 
#ifdef USING_V4L2
static int
set_decode_parms(struct vbi *vbi, struct v4l2_vbi_format *p)
{
    if (p->sample_format != V4L2_PIX_FMT_GREY)
    {
       fprintf(stderr, "got pix fmt %x\n", p->sample_format);
       error("v4l2: unsupported vbi data format");
       return -1;
    }
 
    // some constants from the standard:
    //   horizontal frequency                  fh = 15625Hz
    //   teletext bitrate                      ft = 444*fh = 6937500Hz
    //   teletext identification sequence      10101010 10101010 11100100
    //   13th bit of seq rel to falling hsync  12us -1us +0.4us
    // I search for the clock run-in (10101010 10101010) from 12us-1us-12.5/ft
    // (earliest first bit) to 12us+0.4us+3.5/ft (latest last bit)
    //   earlist first bit                     tf = 12us-1us-12.5/ft = 9.2us
    //   latest last bit                       tl = 12us+0.4us+3.5/ft = 12.9us
    //   total number of used bits             n = (2+1+2+40)*8 = 360
 
    int    bpl = p->samples_per_line; // bytes per line
    double fs = p->sampling_rate; // sampling rate
    double bpb = fs/6937500.0; // bytes per bit
    int    soc = (int)(9.2e-6*fs) - (int)p->offset;  // start of clock run-in
    int    eoc = (int)(12.9e-6*fs) - (int)p->offset; // end of clock run-in
    if (soc < 0)
       soc = 0;
    if (eoc > bpl - (int)(43*8*bpb))
       eoc = bpl - (int)(43*8*bpb);
    if (eoc - soc < (int)(16*bpb))
    {
       // line too short or offset too large or wrong sample_rate
       error("v4l2: broken vbi format specification");
       return -1;
    }
    if (eoc > 240)
    {
       // the vbi_line routine can hold max 240 values in its work buffer
       error("v4l2: unable to handle these sampling parameters");
       return -1;
    }
 
    vbi->bpb = lround(bpb * FAC);
    vbi->soc = soc;
    vbi->eoc = eoc;
    vbi->bp8bl = 0.97 * 8*bpb; // -3% tolerance
    vbi->bp8bh = 1.03 * 8*bpb; // +3% tolerance
 
    vbi->bpl = bpl;
    vbi->bufsize = bpl * (p->count[0] + p->count[1]);
 
    return 0;
}
#endif // USING_V4L2
 
static int
setup_dev([[maybe_unused]] struct vbi *vbi)
{
#ifdef USING_V4L2
    struct v4l2_format v4l2_format {};
    struct v4l2_vbi_format *vbifmt = &v4l2_format.fmt.vbi;
 
    memset(&v4l2_format, 0, sizeof(v4l2_format));
    v4l2_format.type = V4L2_BUF_TYPE_VBI_CAPTURE;
    if (ioctl(vbi->fd, VIDIOC_G_FMT, &v4l2_format) == -1)
    {
       error("Video 4 Linux version 1 support is not enabled.");
       return -1;
    }
 
    if (set_decode_parms(vbi, vbifmt) == -1)
       return -1;
 
    if (vbi->bpl < 1 || vbi->bufsize < vbi->bpl || vbi->bufsize % vbi->bpl != 0)
    {
       error("strange size of vbi buffer (%d/%d)", vbi->bufsize, vbi->bpl);
       return -1;
    }
 
    // grow buffer if necessary
    if (rawbuf_size < vbi->bufsize)
    {
       delete [] rawbuf;
       rawbuf_size = vbi->bufsize;
       if (!(rawbuf = new u_char[rawbuf_size]))
       {
            error("unable to allocate in setup_dev()\n");
       }
    }
 
    return 0;
#else
    return -1;
#endif // USING_V4L2
}
 
 
 
struct vbi *
vbi_open(const char *vbi_dev_name,
         [[maybe_unused]] struct cache *ca,
         int fine_tune,
         int big_buf)
{
    static int s_inited = 0;
    struct vbi *vbi = nullptr;
 
    if (! s_inited)
       lang_init();
    s_inited = 1;
 
    vbi = new struct vbi;
    if (vbi == nullptr)
    {
       error("out of memory");
       goto fail1;
    }
 
    if ((vbi->fd = open(vbi_dev_name, O_RDONLY)) == -1)
    {
       error("cannot open vbi device");
       goto fail2;
    }
 
    if (big_buf != -1)
       error("-oldbttv/-newbttv is obsolete.  option ignored.");
 
    if (setup_dev(vbi) == -1)
       goto fail3;
 
//    vbi->cache = ca;
 
    dl_init(vbi->clients);
    vbi->seq = 0;
    out_of_sync(vbi);
    vbi->ppage = vbi->rpage;
 
    vbi_pll_reset(vbi, fine_tune);
// ECA removed    fdset_add_fd(fds, vbi->fd, vbi_handler, vbi);
    return vbi;
 
fail3:
    close(vbi->fd);
fail2:
    delete vbi;
fail1:
    return nullptr;
}
 
 
 
void
vbi_close(struct vbi *vbi)
{
//    fdset_del_fd(fds, vbi->fd);
//    if (vbi->cache)
//     vbi->cache->op->close(vbi->cache);
    close(vbi->fd);
    delete vbi;
}
 
 
struct vt_page *
vbi_query_page([[maybe_unused]] struct vbi *vbi,
               [[maybe_unused]] int pgno,
               [[maybe_unused]] int subno)
{
#ifdef IMPLEMENTED
    struct vt_page *vtp = 0;
 
    if (vbi->cache)
        vtp = vbi->cache->op->get(vbi->cache, pgno, subno);
    if (vtp == 0)
    {
       // EV_PAGE will come later...
       return 0;
    }
 
    vbi_send(vbi, EV_PAGE, 1, 0, 0, vtp);
    return vtp;
#else
    return nullptr;
#endif
}
 
void
vbi_reset(struct vbi *vbi)
{
//    if (vbi->cache)
//     vbi->cache->op->reset(vbi->cache);
    vbi_send(vbi, EV_RESET, 0, 0, 0, nullptr);
}