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00044 #ifdef HAVE_CONFIG_H
00045 #include <config.h>
00046 #endif
00047
00048 #include "prim_type.h"
00049 #include "fe_internal.h"
00050 #include "fixpoint.h"
00051
00052
00053
00054 static uint32 logtable[] = {
00055 (uint32) (0 * (1 << DEFAULT_RADIX)),
00056 (uint32) (0.0223678130284545 * (1 << DEFAULT_RADIX)),
00057 (uint32) (0.0443941193584534 * (1 << DEFAULT_RADIX)),
00058 (uint32) (0.0660891904577724 * (1 << DEFAULT_RADIX)),
00059 (uint32) (0.0874628412503394 * (1 << DEFAULT_RADIX)),
00060 (uint32) (0.108524456778169 * (1 << DEFAULT_RADIX)),
00061 (uint32) (0.129283016944966 * (1 << DEFAULT_RADIX)),
00062 (uint32) (0.149747119504682 * (1 << DEFAULT_RADIX)),
00063 (uint32) (0.169925001442312 * (1 << DEFAULT_RADIX)),
00064 (uint32) (0.189824558880017 * (1 << DEFAULT_RADIX)),
00065 (uint32) (0.20945336562895 * (1 << DEFAULT_RADIX)),
00066 (uint32) (0.228818690495881 * (1 << DEFAULT_RADIX)),
00067 (uint32) (0.247927513443586 * (1 << DEFAULT_RADIX)),
00068 (uint32) (0.266786540694901 * (1 << DEFAULT_RADIX)),
00069 (uint32) (0.285402218862248 * (1 << DEFAULT_RADIX)),
00070 (uint32) (0.303780748177103 * (1 << DEFAULT_RADIX)),
00071 (uint32) (0.321928094887362 * (1 << DEFAULT_RADIX)),
00072 (uint32) (0.339850002884625 * (1 << DEFAULT_RADIX)),
00073 (uint32) (0.357552004618084 * (1 << DEFAULT_RADIX)),
00074 (uint32) (0.375039431346925 * (1 << DEFAULT_RADIX)),
00075 (uint32) (0.39231742277876 * (1 << DEFAULT_RADIX)),
00076 (uint32) (0.409390936137702 * (1 << DEFAULT_RADIX)),
00077 (uint32) (0.426264754702098 * (1 << DEFAULT_RADIX)),
00078 (uint32) (0.442943495848728 * (1 << DEFAULT_RADIX)),
00079 (uint32) (0.459431618637297 * (1 << DEFAULT_RADIX)),
00080 (uint32) (0.475733430966398 * (1 << DEFAULT_RADIX)),
00081 (uint32) (0.491853096329675 * (1 << DEFAULT_RADIX)),
00082 (uint32) (0.507794640198696 * (1 << DEFAULT_RADIX)),
00083 (uint32) (0.523561956057013 * (1 << DEFAULT_RADIX)),
00084 (uint32) (0.539158811108031 * (1 << DEFAULT_RADIX)),
00085 (uint32) (0.554588851677637 * (1 << DEFAULT_RADIX)),
00086 (uint32) (0.569855608330948 * (1 << DEFAULT_RADIX)),
00087 (uint32) (0.584962500721156 * (1 << DEFAULT_RADIX)),
00088 (uint32) (0.599912842187128 * (1 << DEFAULT_RADIX)),
00089 (uint32) (0.614709844115208 * (1 << DEFAULT_RADIX)),
00090 (uint32) (0.62935662007961 * (1 << DEFAULT_RADIX)),
00091 (uint32) (0.643856189774725 * (1 << DEFAULT_RADIX)),
00092 (uint32) (0.658211482751795 * (1 << DEFAULT_RADIX)),
00093 (uint32) (0.672425341971496 * (1 << DEFAULT_RADIX)),
00094 (uint32) (0.686500527183218 * (1 << DEFAULT_RADIX)),
00095 (uint32) (0.700439718141092 * (1 << DEFAULT_RADIX)),
00096 (uint32) (0.714245517666123 * (1 << DEFAULT_RADIX)),
00097 (uint32) (0.727920454563199 * (1 << DEFAULT_RADIX)),
00098 (uint32) (0.741466986401147 * (1 << DEFAULT_RADIX)),
00099 (uint32) (0.754887502163469 * (1 << DEFAULT_RADIX)),
00100 (uint32) (0.768184324776926 * (1 << DEFAULT_RADIX)),
00101 (uint32) (0.78135971352466 * (1 << DEFAULT_RADIX)),
00102 (uint32) (0.794415866350106 * (1 << DEFAULT_RADIX)),
00103 (uint32) (0.807354922057604 * (1 << DEFAULT_RADIX)),
00104 (uint32) (0.820178962415188 * (1 << DEFAULT_RADIX)),
00105 (uint32) (0.832890014164742 * (1 << DEFAULT_RADIX)),
00106 (uint32) (0.845490050944375 * (1 << DEFAULT_RADIX)),
00107 (uint32) (0.857980995127572 * (1 << DEFAULT_RADIX)),
00108 (uint32) (0.870364719583405 * (1 << DEFAULT_RADIX)),
00109 (uint32) (0.882643049361841 * (1 << DEFAULT_RADIX)),
00110 (uint32) (0.894817763307944 * (1 << DEFAULT_RADIX)),
00111 (uint32) (0.906890595608518 * (1 << DEFAULT_RADIX)),
00112 (uint32) (0.918863237274595 * (1 << DEFAULT_RADIX)),
00113 (uint32) (0.930737337562886 * (1 << DEFAULT_RADIX)),
00114 (uint32) (0.94251450533924 * (1 << DEFAULT_RADIX)),
00115 (uint32) (0.954196310386875 * (1 << DEFAULT_RADIX)),
00116 (uint32) (0.965784284662087 * (1 << DEFAULT_RADIX)),
00117 (uint32) (0.977279923499917 * (1 << DEFAULT_RADIX)),
00118 (uint32) (0.988684686772166 * (1 << DEFAULT_RADIX)),
00119 };
00120
00121 int32
00122 fixlog2(uint32 x)
00123 {
00124 uint32 y;
00125
00126 if (x == 0)
00127 return MIN_FIXLOG2;
00128
00129
00130 #if defined(__GNUC__) && defined(__i386__)
00131 __asm__("bsrl %1, %0\n": "=r"(y): "g"(x):"cc");
00132 x <<= (31 - y);
00133 #elif defined(__ppc__)
00134 __asm__("cntlzw %0, %1\n": "=r"(y):"r"(x));
00135 x <<= y;
00136 y = 31 - y;
00137 #elif defined __ARM_ARCH_5__ || defined __ARM_ARCH_5T__ || defined __ARM_ARCH_5TE__
00138 __asm__("clz %0, %1\n": "=r"(y):"r"(x));
00139 x <<= y;
00140 y = 31 - y;
00141 #else
00142 for (y = 31; y >= 0; --y) {
00143 if (x & 0x80000000)
00144 break;
00145 x <<= 1;
00146 }
00147 #endif
00148 y <<= DEFAULT_RADIX;
00149
00150 x = (x >> 25) & 0x3f;
00151 return y + logtable[x];
00152 }
00153
00154 int
00155 fixlog(uint32 x)
00156 {
00157 int32 y;
00158
00159 if (x == 0)
00160 return MIN_FIXLOG;
00161
00162 y = fixlog2(x);
00163 return FIXMUL(y, FIXLN_2);
00164 }