1 files changed, 72 insertions, 0 deletions
diff --git a/src/math/s_nextafter.c b/src/math/s_nextafter.c
new file mode 100644
index 00000000..46d298ec
--- /dev/null
+++ b/src/math/s_nextafter.c
@@ -0,0 +1,72 @@
+/* @(#)s_nextafter.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * 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.
+ * ====================================================
+ */
+
+/* IEEE functions
+ *      nextafter(x,y)
+ *      return the next machine floating-point number of x in the
+ *      direction toward y.
+ *   Special cases:
+ */
+
+#include <math.h>
+#include "math_private.h"
+
+double
+nextafter(double x, double y)
+{
+        volatile double t;
+        int32_t hx,hy,ix,iy;
+        uint32_t lx,ly;
+
+        EXTRACT_WORDS(hx,lx,x);
+        EXTRACT_WORDS(hy,ly,y);
+        ix = hx&0x7fffffff;             /* |x| */
+        iy = hy&0x7fffffff;             /* |y| */
+
+        if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) ||   /* x is nan */
+           ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0))     /* y is nan */
+           return x+y;
+        if(x==y) return y;              /* x=y, return y */
+        if((ix|lx)==0) {                        /* x == 0 */
+            INSERT_WORDS(x,hy&0x80000000,1);    /* return +-minsubnormal */
+            t = x*x;
+            if(t==x) return t; else return x;   /* raise underflow flag */
+        }
+        if(hx>=0) {                             /* x > 0 */
+            if(hx>hy||((hx==hy)&&(lx>ly))) {    /* x > y, x -= ulp */
+                if(lx==0) hx -= 1;
+                lx -= 1;
+            } else {                            /* x < y, x += ulp */
+                lx += 1;
+                if(lx==0) hx += 1;
+            }
+        } else {                                /* x < 0 */
+            if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
+                if(lx==0) hx -= 1;
+                lx -= 1;
+            } else {                            /* x > y, x += ulp */
+                lx += 1;
+                if(lx==0) hx += 1;
+            }
+        }
+        hy = hx&0x7ff00000;
+        if(hy>=0x7ff00000) return x+x;  /* overflow  */
+        if(hy<0x00100000) {             /* underflow */
+            t = x*x;
+            if(t!=x) {          /* raise underflow flag */
+                INSERT_WORDS(y,hx,lx);
+                return y;
+            }
+        }
+        INSERT_WORDS(x,hx,lx);
+        return x;
+}