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<p>Fibonacci Linear Feedback Shift Register using specified polynomial maskGenerates a maximal length pseudo-random sequence of length 2^degree-1.
<a href="classgri__lfsr.html#details">More...</a></p>
<p><code>#include <<a class="el" href="gri__lfsr_8h_source.html">gri_lfsr.h</a>></code></p>
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<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="pub-methods"></a>
Public Member Functions</h2></td></tr>
<tr class="memitem:a9d75c0d9937724f0784ccbae11114950"><td class="memItemLeft" align="right" valign="top"> </td><td class="memItemRight" valign="bottom"><a class="el" href="classgri__lfsr.html#a9d75c0d9937724f0784ccbae11114950">gri_lfsr</a> (<a class="el" href="stdint_8h.html#a435d1572bf3f880d55459d9805097f62">uint32_t</a> <a class="el" href="classgri__lfsr.html#ab11f525cf4205ac9e77ed3b23d353812">mask</a>, <a class="el" href="stdint_8h.html#a435d1572bf3f880d55459d9805097f62">uint32_t</a> seed, <a class="el" href="stdint_8h.html#a435d1572bf3f880d55459d9805097f62">uint32_t</a> reg_len)</td></tr>
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<tr class="memitem:ab48a354944fe18d9d261be11aa558b0f"><td class="memItemLeft" align="right" valign="top">unsigned char </td><td class="memItemRight" valign="bottom"><a class="el" href="classgri__lfsr.html#ab48a354944fe18d9d261be11aa558b0f">next_bit</a> ()</td></tr>
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<tr class="memitem:afd1989999dcc0306a1b73f5822d38357"><td class="memItemLeft" align="right" valign="top">unsigned char </td><td class="memItemRight" valign="bottom"><a class="el" href="classgri__lfsr.html#afd1989999dcc0306a1b73f5822d38357">next_bit_scramble</a> (unsigned char input)</td></tr>
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<tr class="memitem:af23672b2652cbfa71cd34d99b5b3edd2"><td class="memItemLeft" align="right" valign="top">unsigned char </td><td class="memItemRight" valign="bottom"><a class="el" href="classgri__lfsr.html#af23672b2652cbfa71cd34d99b5b3edd2">next_bit_descramble</a> (unsigned char input)</td></tr>
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<tr class="memitem:a7bddbd6bf10acb53c86239efbeef648e"><td class="memItemLeft" align="right" valign="top"><a class="el" href="volk_8tmpl_8h.html#a8dc2b7da310a28e667530ba0e8ca4cc4">void</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="classgri__lfsr.html#a7bddbd6bf10acb53c86239efbeef648e">reset</a> ()</td></tr>
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<tr class="memitem:af04de11f558b49d79265df6f32f343c1"><td class="memItemLeft" align="right" valign="top"><a class="el" href="volk_8tmpl_8h.html#a8dc2b7da310a28e667530ba0e8ca4cc4">void</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="classgri__lfsr.html#af04de11f558b49d79265df6f32f343c1">pre_shift</a> (int num)</td></tr>
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<tr class="memitem:ab11f525cf4205ac9e77ed3b23d353812"><td class="memItemLeft" align="right" valign="top">int </td><td class="memItemRight" valign="bottom"><a class="el" href="classgri__lfsr.html#ab11f525cf4205ac9e77ed3b23d353812">mask</a> () const </td></tr>
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<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><p>Fibonacci Linear Feedback Shift Register using specified polynomial mask</p>
<p>Generates a maximal length pseudo-random sequence of length 2^degree-1. </p>
<p>Constructor: gri_lfsr(int mask, int seed, int reg_len); </p>
<pre class="fragment"> mask - polynomial coefficients representing the locations
of feedback taps from a shift register which are xor'ed
together to form the new high order bit.
Some common masks might be:
x^4 + x^3 + x^0 = 0x19
x^5 + x^3 + x^0 = 0x29
x^6 + x^5 + x^0 = 0x61
seed - the initialization vector placed into the register
durring initialization. Low order bit corresponds
to x^0 coefficient -- the first to be shifted as output.
</pre><p>reg_len - specifies the length of the feedback shift register to be used. Durring each iteration, the register is rightshifted one and the new bit is placed in bit reg_len. reg_len should generally be at least order(mask) + 1</p>
<p>see <a href="http://en.wikipedia.org/wiki/Linear_feedback_shift_register">http://en.wikipedia.org/wiki/Linear_feedback_shift_register</a> for more explanation.</p>
<p><a class="el" href="classgri__lfsr.html#ab48a354944fe18d9d261be11aa558b0f">next_bit()</a> - Standard LFSR operation </p>
<pre class="fragment">Perform one cycle of the LFSR. The output bit is taken from
the shift register LSB. The shift register MSB is assigned from
the modulo 2 sum of the masked shift register.
</pre><p><a class="el" href="classgri__lfsr.html#afd1989999dcc0306a1b73f5822d38357">next_bit_scramble(unsigned char input)</a> - Scramble an input stream </p>
<pre class="fragment">Perform one cycle of the LFSR. The output bit is taken from
the shift register LSB. The shift register MSB is assigned from
the modulo 2 sum of the masked shift register and the input LSB.
</pre><p><a class="el" href="classgri__lfsr.html#af23672b2652cbfa71cd34d99b5b3edd2">next_bit_descramble(unsigned char input)</a> - Descramble an input stream </p>
<pre class="fragment">Perform one cycle of the LFSR. The output bit is taken from
the modulo 2 sum of the masked shift register and the input LSB.
The shift register MSB is assigned from the LSB of the input.
</pre><p>See <a href="http://en.wikipedia.org/wiki/Scrambler">http://en.wikipedia.org/wiki/Scrambler</a> for operation of these last two functions (see multiplicative scrambler.) </p>
</div><h2 class="groupheader">Constructor & Destructor Documentation</h2>
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<td class="paramtype"><a class="el" href="stdint_8h.html#a435d1572bf3f880d55459d9805097f62">uint32_t</a> </td>
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<td class="memname">int gri_lfsr::mask </td>
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<td class="memname">unsigned char gri_lfsr::next_bit </td>
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<td class="memname">unsigned char gri_lfsr::next_bit_descramble </td>
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<td class="memname">unsigned char gri_lfsr::next_bit_scramble </td>
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<td class="memname"><a class="el" href="volk_8tmpl_8h.html#a8dc2b7da310a28e667530ba0e8ca4cc4">void</a> gri_lfsr::pre_shift </td>
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<p>Rotate the register through x number of bits where we are just throwing away the results to get queued up correctly </p>
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<td class="memname"><a class="el" href="volk_8tmpl_8h.html#a8dc2b7da310a28e667530ba0e8ca4cc4">void</a> gri_lfsr::reset </td>
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<p>Reset shift register to initial seed value </p>
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<hr/>The documentation for this class was generated from the following file:<ul>
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