feat(math): abs/round/trunc/frexp/ldexp/scalbn/copysign/fmin/fmax/fmod

src/math/lrint.c

@@ -0,0 +1,49 @@
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <math.h>
+
+/*
+ * The nearest integral value to x in the current rounding direction,
+ * returned as long (C23 7.12.9.7), all three precisions. A result
+ * outside the range of long is a range error whose return value is
+ * unspecified, so the header declares no const attribute; the test
+ * corpus keeps |x| < 2^62 where every result is exact.
+ *
+ * GCC never folds the __builtin_lrint* forms on this target (external
+ * lrint@PLT calls at every optimization level), so lrint is built as
+ * rint-then-convert: __builtin_rint* folds to the in-line round-to-
+ * nearest-even sequence (see rint.c), producing an exact integral value,
+ * and the cast to long is then exact no matter which conversion
+ * instruction GCC emits. The rint step honors the MXCSR/x87 rounding
+ * mode, the only reachable one being the default round-to-nearest-even
+ * (no <fenv.h> exists in vlibc yet).
+ */
+
+/*
+ * As lrint, for a float argument.
+ */
+long
+lrintf(float x)
+{
+    return (long)__builtin_rintf(x);
+}
+
+/*
+ * As lrint, for a double argument.
+ */
+long
+lrint(double x)
+{
+    return (long)__builtin_rint(x);
+}
+
+/*
+ * As lrint, for a long double argument.
+ */
+long
+lrintl(long double x)
+{
+    return (long)__builtin_rintl(x);
+}