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<title>BCD arithmetic for Teletext page numbers</title>
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<hr><h1>BCD arithmetic for Teletext page numbers<br>
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[<a class="el" href="group__Service.html">Data Service Decoder</a>]</small>
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<tr><td colspan=2><br><h2>Functions</h2></td></tr>
<tr><td nowrap align=right valign=top>static_inline unsigned int </td><td valign=bottom><a class="el" href="group__BCD.html#a0">vbi_dec2bcd</a> (unsigned int dec)</td></tr>
<tr><td nowrap align=right valign=top>static_inline unsigned int </td><td valign=bottom><a class="el" href="group__BCD.html#a1">vbi_bcd2dec</a> (unsigned int bcd)</td></tr>
<tr><td nowrap align=right valign=top>static_inline unsigned int </td><td valign=bottom><a class="el" href="group__BCD.html#a2">vbi_add_bcd</a> (unsigned int a, unsigned int b)</td></tr>
<tr><td nowrap align=right valign=top>static_inline vbi_bool </td><td valign=bottom><a class="el" href="group__BCD.html#a3">vbi_is_bcd</a> (unsigned int bcd)</td></tr>
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<hr><a name="_details"></a><h2>Detailed Description</h2>
Teletext page numbers are expressed as binary coded decimal numbers in range 0x100 to 0x8FF. The bcd format encodes one decimal digit in every hex nibble (four bits) of the number. Page numbers containing digits 0xA to 0xF are reserved for various system purposes and not intended for display. <hr><h2>Function Documentation</h2>
<a name="a0" doxytag="bcd.h::vbi_dec2bcd"></a><p>
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<td class="md" nowrap valign="top"> static_inline unsigned int vbi_dec2bcd </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top">unsigned int </td>
<td class="mdname1" valign="top" nowrap> <em>dec</em> </td>
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<dl compact><dt><b>Parameters: </b></dt><dd>
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<tr><td valign=top><em>dec</em> </td><td>
Decimal number.</td></tr>
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</dl>Converts a decimal number between 0 ... 999 to a bcd number in range 0x000 ... 0x999. Extra digits in the input will be discarded.
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<dl compact><dt><b>Returns: </b></dt><dd>
BCD number. </dl> </td>
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<td class="md" nowrap valign="top"> static_inline unsigned int vbi_bcd2dec </td>
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<td class="md" nowrap valign="top">unsigned int </td>
<td class="mdname1" valign="top" nowrap> <em>bcd</em> </td>
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<dl compact><dt><b>Parameters: </b></dt><dd>
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<tr><td valign=top><em>bcd</em> </td><td>
BCD number.</td></tr>
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</dl>Converts a bcd number between 0x000 ... 0xFFF to a decimal number in range 0 ... 999. Extra digits in the input will be discarded.
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<dl compact><dt><b>Returns: </b></dt><dd>
Decimal number. The result is undefined when the bcd number contains hex digits 0xA ... 0xF. </dl> </td>
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<a name="a2" doxytag="bcd.h::vbi_add_bcd"></a><p>
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<td class="md" nowrap valign="top"> static_inline unsigned int vbi_add_bcd </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top">unsigned int </td>
<td class="mdname" nowrap> <em>a</em>, </td>
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<td class="md" nowrap>unsigned int </td>
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<td class="md">) </td>
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<dl compact><dt><b>Parameters: </b></dt><dd>
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<tr><td valign=top><em>a</em> </td><td>
BCD number. </td></tr>
<tr><td valign=top><em>b</em> </td><td>
BCD number.</td></tr>
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</dl>Adds two bcd numbers, returning a bcd sum. The result will be in range 0x0000 0000 ... 0x9999 9999, discarding carry and extra digits in the inputs. To subtract you can add the complement, e. g. -0x1 = +0x9999 9999.
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<dl compact><dt><b>Returns: </b></dt><dd>
BCD number. The result is undefined when the bcd number contains hex digits 0xA ... 0xF. </dl> </td>
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<td class="md" nowrap valign="top"> static_inline vbi_bool vbi_is_bcd </td>
<td class="md" valign="top">( </td>
<td class="md" nowrap valign="top">unsigned int </td>
<td class="mdname1" valign="top" nowrap> <em>bcd</em> </td>
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<dl compact><dt><b>Parameters: </b></dt><dd>
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<tr><td valign=top><em>bcd</em> </td><td>
BCD number.</td></tr>
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</dl>Tests if <em>bcd</em> forms a valid BCD number.
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<dl compact><dt><b>Returns: </b></dt><dd>
<code>FALSE</code> if <em>bcd</em> contains hex digits 0xA ... 0xF. </dl> </td>
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