4ab58f704d
git-svn-id: svn://svn.openwrt.org/openwrt/packages@16802 3c298f89-4303-0410-b956-a3cf2f4a3e73
150 lines
2.7 KiB
Diff
150 lines
2.7 KiB
Diff
--- a/lib/ipmi_sdr.c
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+++ b/lib/ipmi_sdr.c
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@@ -4399,3 +4399,146 @@ ipmi_sdr_main(struct ipmi_intf *intf, in
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return rc;
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}
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+
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+/* cbrt.c
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+ *
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+ * Cube root
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+ *
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+ *
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+ *
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+ * SYNOPSIS:
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+ *
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+ * double x, y, cbrt();
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+ *
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+ * y = cbrt( x );
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+ *
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+ *
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+ *
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+ * DESCRIPTION:
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+ *
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+ * Returns the cube root of the argument, which may be negative.
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+ *
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+ * Range reduction involves determining the power of 2 of
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+ * the argument. A polynomial of degree 2 applied to the
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+ * mantissa, and multiplication by the cube root of 1, 2, or 4
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+ * approximates the root to within about 0.1%. Then Newton's
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+ * iteration is used three times to converge to an accurate
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+ * result.
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+ *
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+ *
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+ *
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+ * ACCURACY:
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+ *
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+ * Relative error:
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+ * arithmetic domain # trials peak rms
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+ * DEC -10,10 200000 1.8e-17 6.2e-18
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+ * IEEE 0,1e308 30000 1.5e-16 5.0e-17
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+ *
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+ */
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+/* cbrt.c */
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+
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+/*
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+Cephes Math Library Release 2.8: June, 2000
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+Copyright 1984, 1991, 2000 by Stephen L. Moshier
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+*/
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+
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+
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+static double CBRT2 = 1.2599210498948731647672;
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+static double CBRT4 = 1.5874010519681994747517;
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+static double CBRT2I = 0.79370052598409973737585;
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+static double CBRT4I = 0.62996052494743658238361;
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+
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+#ifdef ANSIPROT
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+extern double frexp ( double, int * );
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+extern double ldexp ( double, int );
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+extern int isnan ( double );
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+extern int isfinite ( double );
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+#else
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+/*
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+double frexp(), ldexp();
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+int isnan(double), isfinite(double);
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+*/
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+#endif
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+
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+double cbrt(double x)
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+{
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+/* double x; */
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+int e, rem, sign;
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+double z;
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+
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+#ifdef NANS
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+if( isnan(x) )
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+ return x;
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+#endif
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+#ifdef INFINITIES
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+if( !isfinite(x) )
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+ return x;
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+#endif
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+if( x == 0 )
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+ return( x );
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+if( x > 0 )
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+ sign = 1;
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+else
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+ {
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+ sign = -1;
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+ x = -x;
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+ }
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+
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+z = x;
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+/* extract power of 2, leaving
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+ * mantissa between 0.5 and 1
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+ */
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+x = frexp( x, &e );
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+
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+/* Approximate cube root of number between .5 and 1,
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+ * peak relative error = 9.2e-6
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+ */
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+x = (((-1.3466110473359520655053e-1 * x
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+ + 5.4664601366395524503440e-1) * x
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+ - 9.5438224771509446525043e-1) * x
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+ + 1.1399983354717293273738e0 ) * x
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+ + 4.0238979564544752126924e-1;
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+
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+/* exponent divided by 3 */
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+if( e >= 0 )
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+ {
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+ rem = e;
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+ e /= 3;
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+ rem -= 3*e;
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+ if( rem == 1 )
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+ x *= CBRT2;
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+ else if( rem == 2 )
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+ x *= CBRT4;
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+ }
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+
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+
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+/* argument less than 1 */
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+
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+else
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+ {
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+ e = -e;
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+ rem = e;
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+ e /= 3;
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+ rem -= 3*e;
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+ if( rem == 1 )
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+ x *= CBRT2I;
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+ else if( rem == 2 )
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+ x *= CBRT4I;
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+ e = -e;
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+ }
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+
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+/* multiply by power of 2 */
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+x = ldexp( x, e );
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+
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+/* Newton iteration */
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+x -= ( x - (z/(x*x)) )*0.33333333333333333333;
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+#ifdef DEC
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+x -= ( x - (z/(x*x)) )/3.0;
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+#else
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+x -= ( x - (z/(x*x)) )*0.33333333333333333333;
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+#endif
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+
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+if( sign < 0 )
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+ x = -x;
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+return(x);
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+}
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