fix_8cpp-source.html

来自「这个是关于G.726算法的源程序」· HTML 代码 · 共 709 行 · 第 1/5 页

<a name="l00299"></a>00299     a &lt;&lt;= 1;
<a name="l00300"></a>00300     <span class="keywordflow">if</span>((<a class="code" href="group__integers.html#ga2">uint32</a>)a&gt;=(<a class="code" href="group__integers.html#ga2">uint32</a>)b)
<a name="l00301"></a>00301         a -= b, r += 1&lt;&lt;2;
<a name="l00302"></a>00302     a &lt;&lt;= 1;
<a name="l00303"></a>00303     <span class="keywordflow">if</span>((<a class="code" href="group__integers.html#ga2">uint32</a>)a&gt;=(<a class="code" href="group__integers.html#ga2">uint32</a>)b)
<a name="l00304"></a>00304         a -= b, r += 1&lt;&lt;1;
<a name="l00305"></a>00305     a &lt;&lt;= 1;
<a name="l00306"></a>00306     <span class="keywordflow">if</span>((<a class="code" href="group__integers.html#ga2">uint32</a>)a&gt;=(<a class="code" href="group__integers.html#ga2">uint32</a>)b)
<a name="l00307"></a>00307         a -= b, r += 1&lt;&lt;0;
<a name="l00308"></a>00308 
<a name="l00309"></a>00309 <span class="preprocessor">#endif</span>
<a name="l00310"></a>00310 <span class="preprocessor"></span>
<a name="l00311"></a>00311     <span class="keywordflow">return</span> (r&lt;0) ? 0x80000000-r : r;
<a name="l00312"></a>00312 
<a name="l00313"></a>00313     }
<a name="l00314"></a>00314 
<a name="l00315"></a>00315 
<a name="l00316"></a><a class="code" href="classFix.html#e5">00316</a> <a class="code" href="common_8h.html#a2">EXPORT</a> <a class="code" href="group__fix.html#ga0">fix</a> <a class="code" href="classFix.html#e5">Fix::Sqrt</a>(<a class="code" href="group__fix.html#ga1">ufix</a> a)
<a name="l00317"></a>00317     {
<a name="l00318"></a>00318     <a class="code" href="group__fix.html#ga1">ufix</a> r,nr,m;
<a name="l00319"></a>00319 
<a name="l00320"></a>00320     <span class="comment">// calculate integer part (bits 31 to 16)</span>
<a name="l00321"></a>00321     r = 0;
<a name="l00322"></a>00322     m = 0x40000000;
<a name="l00323"></a>00323     <span class="keywordflow">do</span>
<a name="l00324"></a>00324         {
<a name="l00325"></a>00325         nr = r+m;
<a name="l00326"></a>00326         <span class="keywordflow">if</span>(nr&lt;=a)
<a name="l00327"></a>00327             {
<a name="l00328"></a>00328             a -= nr;
<a name="l00329"></a>00329             r = nr+m;
<a name="l00330"></a>00330             }
<a name="l00331"></a>00331         r &gt;&gt;= 1;
<a name="l00332"></a>00332         m &gt;&gt;= 2;
<a name="l00333"></a>00333         }
<a name="l00334"></a>00334     <span class="keywordflow">while</span>(m);
<a name="l00335"></a>00335 
<a name="l00336"></a>00336     <span class="comment">// calculate bits 15 to 8</span>
<a name="l00337"></a>00337     r &lt;&lt;= 8;
<a name="l00338"></a>00338     a &lt;&lt;= 8;
<a name="l00339"></a>00339     m = 0x40;
<a name="l00340"></a>00340     <span class="keywordflow">do</span>
<a name="l00341"></a>00341         {
<a name="l00342"></a>00342         nr = r+m;
<a name="l00343"></a>00343         <span class="keywordflow">if</span>(nr&lt;=a)
<a name="l00344"></a>00344             {
<a name="l00345"></a>00345             a -= nr;
<a name="l00346"></a>00346             r = nr+m;
<a name="l00347"></a>00347             }
<a name="l00348"></a>00348         r &gt;&gt;= 1;
<a name="l00349"></a>00349         m &gt;&gt;= 2;
<a name="l00350"></a>00350         }
<a name="l00351"></a>00351     <span class="keywordflow">while</span>(m);
<a name="l00352"></a>00352 
<a name="l00353"></a>00353     <span class="comment">// calculate bits 7 to 0</span>
<a name="l00354"></a>00354     r &lt;&lt;= 8;
<a name="l00355"></a>00355     a &lt;&lt;= 8;
<a name="l00356"></a>00356     m = 0x40;
<a name="l00357"></a>00357     <span class="keywordflow">do</span>
<a name="l00358"></a>00358         {
<a name="l00359"></a>00359         nr = r+m;
<a name="l00360"></a>00360         <span class="keywordflow">if</span>(nr&lt;=a)
<a name="l00361"></a>00361             {
<a name="l00362"></a>00362             a -= nr;
<a name="l00363"></a>00363             r = nr+m;
<a name="l00364"></a>00364             }
<a name="l00365"></a>00365         r &gt;&gt;= 1;
<a name="l00366"></a>00366         m &gt;&gt;= 2;
<a name="l00367"></a>00367         }
<a name="l00368"></a>00368     <span class="keywordflow">while</span>(m);
<a name="l00369"></a>00369 
<a name="l00370"></a>00370     <span class="comment">// round result</span>
<a name="l00371"></a>00371     <span class="keywordflow">if</span>(r&lt;a)
<a name="l00372"></a>00372         r++;
<a name="l00373"></a>00373     
<a name="l00374"></a>00374     <span class="keywordflow">return</span> r;
<a name="l00375"></a>00375     }
<a name="l00376"></a>00376 
<a name="l00377"></a>00377 
<a name="l00378"></a><a class="code" href="classFix.html#e6">00378</a> <a class="code" href="common_8h.html#a2">EXPORT</a> <a class="code" href="group__fix.html#ga0">fix</a> <a class="code" href="classFix.html#e6">Fix::Log2</a>(<a class="code" href="group__fix.html#ga1">ufix</a> a)
<a name="l00379"></a>00379     {
<a name="l00380"></a>00380     <span class="comment">// trap 0</span>
<a name="l00381"></a>00381     <span class="keywordflow">if</span>(a==0)
<a name="l00382"></a>00382         <span class="keywordflow">return</span> (<a class="code" href="group__fix.html#ga0">fix</a>)-0x80000000;
<a name="l00383"></a>00383 
<a name="l00384"></a>00384     <span class="comment">// calculate integer part of result in i</span>
<a name="l00385"></a>00385     <span class="comment">// and set n = normalised value of a</span>
<a name="l00386"></a>00386     <a class="code" href="group__integers.html#ga5">int32</a> i=15*0x10000;
<a name="l00387"></a>00387     <a class="code" href="group__integers.html#ga2">uint32</a> n=a;
<a name="l00388"></a>00388     <span class="keywordflow">if</span>(n&lt;(<a class="code" href="group__integers.html#ga2">uint32</a>)(1&lt;&lt;(32-16)))
<a name="l00389"></a>00389         n &lt;&lt;= 16, i -= 16*0x10000;
<a name="l00390"></a>00390     <span class="keywordflow">if</span>(n&lt;(<a class="code" href="group__integers.html#ga2">uint32</a>)(1&lt;&lt;(32-8)))
<a name="l00391"></a>00391         n &lt;&lt;= 8, i -= 8*0x10000;
<a name="l00392"></a>00392     <span class="keywordflow">if</span>(n&lt;(<a class="code" href="group__integers.html#ga2">uint32</a>)(1&lt;&lt;(32-4)))
<a name="l00393"></a>00393         n &lt;&lt;= 4, i -= 4*0x10000;
<a name="l00394"></a>00394     <span class="keywordflow">if</span>(n&lt;(<a class="code" href="group__integers.html#ga2">uint32</a>)(1&lt;&lt;(32-2)))
<a name="l00395"></a>00395         n &lt;&lt;= 2, i -= 2*0x10000;
<a name="l00396"></a>00396     <span class="keywordflow">if</span>(n&lt;(<a class="code" href="group__integers.html#ga2">uint32</a>)(1&lt;&lt;(32-1)))
<a name="l00397"></a>00397         n &lt;&lt;= 1, i -= 1*0x10000;
<a name="l00398"></a>00398 
<a name="l00399"></a>00399     <span class="comment">// reduce n to the 23 most significant bits and clear</span>
<a name="l00400"></a>00400     <span class="comment">// the most significant bit, leaving a 22 bit value in n</span>
<a name="l00401"></a>00401     n = (n-0x80000000+(1&lt;&lt;8))&gt;&gt;9;
<a name="l00402"></a>00402 
<a name="l00403"></a>00403     <span class="comment">// calculate fractional part of result (in f) by interpolation of lookup table values</span>
<a name="l00404"></a>00404     <span class="keyword">static</span> <span class="keyword">const</span> <a class="code" href="group__integers.html#ga5">int32</a> LogTable[] =
<a name="l00405"></a>00405         {
<a name="l00406"></a>00406         0xffff45e1,
<a name="l00407"></a>00407         0x00000000,0x0000b73d,0x00016bad,0x00021d67,0x0002cc7f,0x00037908,0x00042316,0x0004caba,
<a name="l00408"></a>00408         0x00057007,0x0006130b,0x0006b3d8,0x0007527c,0x0007ef06,0x00088984,0x00092204,0x0009b892,
<a name="l00409"></a>00409         0x000a4d3c,0x000ae00d,0x000b7111,0x000c0053,0x000c8ddd,0x000d19bb,0x000da3f6,0x000e2c98,
<a name="l00410"></a>00410         0x000eb3aa,0x000f3935,0x000fbd43,0x00103fdb,0x0010c105,0x001140ca,0x0011bf31,0x00123c42,
<a name="l00411"></a>00411         0x0012b803,0x0013327c,0x0013abb4,0x001423b0,0x00149a78,0x00151012,0x00158482,0x0015f7d0,
<a name="l00412"></a>00412         0x00166a01,0x0016db19,0x00174b20,0x0017ba19,0x0018280a,0x001894f7,0x001900e6,0x00196bdb,
<a name="l00413"></a>00413         0x0019d5da,0x001a3ee8,0x001aa709,0x001b0e41,0x001b7495,0x001bda07,0x001c3e9d,0x001ca259,
<a name="l00414"></a>00414         0x001d053f,0x001d6754,0x001dc89a,0x001e2914,0x001e88c7,0x001ee7b4,0x001f45e1,0x001fa34e,
<a name="l00415"></a>00415         0x00200000,0x00205bf9,0x0020b73d
<a name="l00416"></a>00416         };
<a name="l00417"></a>00417     <a class="code" href="group__integers.html#ga5">int32</a> f = <a class="code" href="fix_8cpp.html#a0">Interpolate</a>(LogTable,n,16);
<a name="l00418"></a>00418 
<a name="l00419"></a>00419     <span class="comment">// scale result to 16 bits (from the 22 bit precision used in lookup table)</span>
<a name="l00420"></a>00420     f = (f+(1&lt;&lt;(5-1)))&gt;&gt;5;
<a name="l00421"></a>00421 
<a name="l00422"></a>00422     <span class="comment">// return sum of integer and fractional part</span>
<a name="l00423"></a>00423     <span class="keywordflow">return</span> i+f;
<a name="l00424"></a>00424     }
<a name="l00425"></a>00425 
<a name="l00426"></a>00426 
<a name="l00427"></a><a class="code" href="classFix.html#e7">00427</a> <a class="code" href="common_8h.html#a2">EXPORT</a> <a class="code" href="group__fix.html#ga1">ufix</a> <a class="code" href="classFix.html#e7">Fix::Exp2</a>(<a class="code" href="group__fix.html#ga0">fix</a> a)
<a name="l00428"></a>00428     {
<a name="l00429"></a>00429     <span class="keywordflow">if</span>(a&gt;=0x00100000)
<a name="l00430"></a>00430         <span class="keywordflow">return</span> 0xffffffffu; <span class="comment">// result will be too big so result max value</span>
<a name="l00431"></a>00431 
<a name="l00432"></a>00432     <span class="comment">// special cases for small values</span>
<a name="l00433"></a>00433     <span class="keywordflow">if</span>(a&lt;-0x000ead96)
<a name="l00434"></a>00434         {
<a name="l00435"></a>00435         <span class="keywordflow">if</span>(a&lt;-0x00110000)
<a name="l00436"></a>00436             <span class="keywordflow">return</span> 0;
<a name="l00437"></a>00437         <span class="keywordflow">if</span>(a&lt;-0x000f6a3f)
<a name="l00438"></a>00438             <span class="keywordflow">return</span> 1;
<a name="l00439"></a>00439         <span class="keywordflow">return</span> 2;
<a name="l00440"></a>00440         }