cleanup

[rpikern] / src / libc / math.c

diff --git a/src/libc/math.c b/src/libc/math.c
new file mode 100644 (file)
index 0000000..8da9a15
--- /dev/null
+++ b/src/libc/math.c
@@ -0,0 +1,38 @@
+#include "math.h"
+
+static double calc_pow(double x, double y, double precision);
+
+double pow(double x, double y)
+{
+       if(y == 0.0 || y == -0.0) {
+               return 1.0;
+       }
+       if(y == 1.0) {
+               return x;
+       }
+       if(y == -INFINITY) {
+               return fabs(x) < 1.0 ? INFINITY : 0.0;
+       }
+       if(y == INFINITY) {
+               return fabs(x) < 1.0 ? 0.0 : INFINITY;
+       }
+       return calc_pow(x, y, 1e-6);
+}
+
+static double calc_pow(double x, double y, double precision)
+{
+       if(y < 0.0) {
+               return 1.0 / calc_pow(x, -y, precision);
+       }
+       if(y >= 10.0) {
+               double p = calc_pow(x, y / 2.0, precision / 2.0);
+               return p * p;
+       }
+       if(y >= 1.0) {
+               return x * calc_pow(x, y - 1.0, precision);
+       }
+       if(precision >= 1) {
+               return __builtin_sqrt(x);
+       }
+       return __builtin_sqrt(calc_pow(x, y * 2.0, precision * 2.0));
+}