/// <summary>
/// Decodes the toptext multi page.
/// </summary>
/// <param name="cache">The cache.</param>
private void DecodeMultiPage(TeletextPageCache cache)
{
// multi page contains the number of subpages transmitted for each page (100-899);
if (!cache.PageExists(TOP_MULTI_PAGE))
{
return;
}
byte[] multiPage = cache.GetPage(TOP_MULTI_PAGE, 0);
for (int pageNr = 100; pageNr <= 899; pageNr++)
{
int row = ((pageNr - 100) / 40) + 1;
int col = ((pageNr - 100) % 40) + 2;
byte data = Hamming.Decode[multiPage[row * 42 + col]];
if (data == NotPresent)
{
//page is offair
_pageSubCount[pageNr] = 0;
}
else if (data == 0x0a)
{
//page has > 10 subpages
_pageSubCount[pageNr] = 10; //( or more)
}
else
{
int numberOfSubPages = data - 1;
_pageSubCount[pageNr] = numberOfSubPages;
}
}
}
/// <summary>
/// Decodes the additional toptext pages.
/// </summary>
/// <param name="cache">The cache.</param>
private void DecodeAdditionalPages(TeletextPageCache cache)
{
//addditional pages carry information to display on line 24
//
for (int pageNr = TOP_ADDITIONAL_PAGE; pageNr < 0x1fd; ++pageNr)
{
if (!cache.PageExists(pageNr))
{
continue;
}
byte[] additionalPage = cache.GetPage(pageNr, 0);
int lineCounter = 0;
while (true)
{
int row = 1 + (lineCounter / 2);
int col = (20 * (lineCounter % 2));
byte magazine = Hamming.Decode[additionalPage[row * 42 + 2 + col]];
byte pageTens = Hamming.Decode[additionalPage[row * 42 + 3 + col]];
byte pageUnits = Hamming.Decode[additionalPage[row * 42 + 4 + col]];
if (magazine >= 0 && magazine <= 7)
{
if (pageTens >= 0x0 && pageTens <= 9)
{
if (pageUnits >= 0x0 && pageUnits <= 9)
{
string description = String.Empty;
for (int i = 1; i < 12; ++i)
{
row = 1 + (lineCounter / 2);
col = 9 + i + (20 * (lineCounter % 2));
description += (char)(additionalPage[row * 42 + col] & 0x7f);
}
if (magazine == 0)
{
magazine = 8;
}
int pageNo = magazine * 100 + pageTens * 10 + pageUnits;
if (pageNo >= 100 && pageNo <= 899)
{
_pageDescription[pageNo] = description;
}
}
}
}
lineCounter++;
if (lineCounter >= 43)
{
break;
}
}
}
}
/// <summary>
/// Decodes the basic toptext page.
/// </summary>
/// <param name="cache">The cache.</param>
/// <returns></returns>
private bool DecodeBasicPage(TeletextPageCache cache)
{
//basic toppage contains information which teletext pages are onair
//and if onair if it has subpages or not
//also contains the type for each page
if (!cache.PageExists(TOP_BASIC_PAGE))
{
return(false);
}
byte[] basicPage = cache.GetPage(TOP_BASIC_PAGE, 0);
for (int pageNr = 100; pageNr <= 899; pageNr++)
{
int row = ((pageNr - 100) / 40) + 1;
int col = ((pageNr - 100) % 40) + 2;
byte data = Hamming.Decode[basicPage[row * 42 + col]];
if (data == ProgramInfoBlockPageMulti ||
data == BlockPageMulti ||
data == GroupPageMulti ||
data == NormalPageMulti ||
data == NormalPageMultiInfo
)
{
//page is onair and has subpages
_pageType[pageNr] = data;
}
if (data == ProgramInfoBlockPageSingle ||
data == BlockPageSingle ||
data == GroupPageSingle ||
data == NormalPage ||
data == NormalPageInfo)
{
//page is onair and has subpages
_pageType[pageNr] = data;
}
if (data == NotPresent)
{
//page is not onair
_pageType[pageNr] = data;
_pageSubCount[pageNr] = 0;
}
}
return(true);
}
/// <summary>
/// Decodes the additional toptext pages.
/// </summary>
/// <param name="cache">The cache.</param>
private void DecodeAdditionalPages(TeletextPageCache cache)
{
//addditional pages carry information to display on line 24
//
for (int pageNr = TOP_ADDITIONAL_PAGE; pageNr < 0x1fd; ++pageNr)
{
if (!cache.PageExists(pageNr))
continue;
byte[] additionalPage = cache.GetPage(pageNr, 0);
int lineCounter = 0;
while (true)
{
int row = 1 + (lineCounter / 2);
int col = (20 * (lineCounter % 2));
byte magazine = Hamming.Decode[additionalPage[row * 42 + 2 + col]];
byte pageTens = Hamming.Decode[additionalPage[row * 42 + 3 + col]];
byte pageUnits = Hamming.Decode[additionalPage[row * 42 + 4 + col]];
if (magazine >= 0 && magazine <= 7)
{
if (pageTens >= 0x0 && pageTens <= 9)
{
if (pageUnits >= 0x0 && pageUnits <= 9)
{
string description = String.Empty;
for (int i = 1; i < 12; ++i)
{
row = 1 + (lineCounter / 2);
col = 9 + i + (20 * (lineCounter % 2));
description += (char)(additionalPage[row * 42 + col] & 0x7f);
}
if (magazine == 0)
magazine = 8;
int pageNo = magazine * 100 + pageTens * 10 + pageUnits;
if (pageNo >= 100 && pageNo <= 899)
{
_pageDescription[pageNo] = description;
}
}
}
}
lineCounter++;
if (lineCounter >= 43)
break;
}
}
}
/// <summary>
/// Decodes the toptext multi page.
/// </summary>
/// <param name="cache">The cache.</param>
private void DecodeMultiPage(TeletextPageCache cache)
{
// multi page contains the number of subpages transmitted for each page (100-899);
if (!cache.PageExists(TOP_MULTI_PAGE))
return;
byte[] multiPage = cache.GetPage(TOP_MULTI_PAGE, 0);
for (int pageNr = 100; pageNr <= 899; pageNr++)
{
int row = ((pageNr - 100) / 40) + 1;
int col = ((pageNr - 100) % 40) + 2;
byte data = Hamming.Decode[multiPage[row * 42 + col]];
if (data == NotPresent)
{
//page is offair
_pageSubCount[pageNr] = 0;
}
else if (data == 0x0a)
{
//page has > 10 subpages
_pageSubCount[pageNr] = 10; //( or more)
}
else
{
int numberOfSubPages = data - 1;
_pageSubCount[pageNr] = numberOfSubPages;
}
}
}
/// <summary>
/// Decodes the basic toptext page.
/// </summary>
/// <param name="cache">The cache.</param>
/// <returns></returns>
private bool DecodeBasicPage(TeletextPageCache cache)
{
//basic toppage contains information which teletext pages are onair
//and if onair if it has subpages or not
//also contains the type for each page
if (!cache.PageExists(TOP_BASIC_PAGE))
return false;
byte[] basicPage = cache.GetPage(TOP_BASIC_PAGE, 0);
for (int pageNr = 100; pageNr <= 899; pageNr++)
{
int row = ((pageNr - 100) / 40) + 1;
int col = ((pageNr - 100) % 40) + 2;
byte data = Hamming.Decode[basicPage[row * 42 + col]];
if (data == ProgramInfoBlockPageMulti ||
data == BlockPageMulti ||
data == GroupPageMulti ||
data == NormalPageMulti ||
data == NormalPageMultiInfo
)
{
//page is onair and has subpages
_pageType[pageNr] = data;
}
if (data == ProgramInfoBlockPageSingle ||
data == BlockPageSingle ||
data == GroupPageSingle ||
data == NormalPage ||
data == NormalPageInfo)
{
//page is onair and has subpages
_pageType[pageNr] = data;
}
if (data == NotPresent)
{
//page is not onair
_pageType[pageNr] = data;
_pageSubCount[pageNr] = 0;
}
}
return true;
}
