initial commit, 4.5 stable

thirdparty/sdl/libm/s_modf.c

@@ -0,0 +1,68 @@
+#include "SDL_internal.h"
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+/*
+ * modf(double x, double *iptr)
+ * return fraction part of x, and return x's integral part in *iptr.
+ * Method:
+ *	Bit twiddling.
+ *
+ * Exception:
+ *	No exception.
+ */
+
+#include "math_libm.h"
+#include "math_private.h"
+
+static const double one = 1.0;
+
+double modf(double x, double *iptr)
+{
+	int32_t i0,i1,_j0;
+	u_int32_t i;
+	EXTRACT_WORDS(i0,i1,x);
+	_j0 = ((i0>>20)&0x7ff)-0x3ff;	/* exponent of x */
+	if(_j0<20) {			/* integer part in high x */
+	    if(_j0<0) {			/* |x|<1 */
+	        INSERT_WORDS(*iptr,i0&0x80000000,0);	/* *iptr = +-0 */
+		return x;
+	    } else {
+		i = (0x000fffff)>>_j0;
+		if(((i0&i)|i1)==0) {		/* x is integral */
+		    *iptr = x;
+		    INSERT_WORDS(x,i0&0x80000000,0);	/* return +-0 */
+		    return x;
+		} else {
+		    INSERT_WORDS(*iptr,i0&(~i),0);
+		    return x - *iptr;
+		}
+	    }
+	} else if (_j0>51) {		/* no fraction part */
+	    *iptr = x*one;
+	    /* We must handle NaNs separately.  */
+	    if (_j0 == 0x400 && ((i0 & 0xfffff) | i1))
+	      return x*one;
+	    INSERT_WORDS(x,i0&0x80000000,0);	/* return +-0 */
+	    return x;
+	} else {			/* fraction part in low x */
+	    i = ((u_int32_t)(0xffffffff))>>(_j0-20);
+	    if((i1&i)==0) { 		/* x is integral */
+		*iptr = x;
+		INSERT_WORDS(x,i0&0x80000000,0);	/* return +-0 */
+		return x;
+	    } else {
+	        INSERT_WORDS(*iptr,i0,i1&(~i));
+		return x - *iptr;
+	    }
+	}
+}
+libm_hidden_def(modf)