Changeset ca113cf in mainline

Timestamp:

2021-06-18T16:06:10Z (3 years ago)

Author:

Maurizio Lombardi <mlombard@…>

Children:

f23dbf4

Parents:

197d59d

git-author:

Maurizio Lombardi <mlombard@…> (2018-11-25 16:51:03)

git-committer:

Maurizio Lombardi <mlombard@…> (2021-06-18 16:06:10)

Message:

math: sync sqrt() to FreeBSD 11.2

File:

• uspace/lib/math/generic/sqrt.c (modified) (2 diffs)

uspace/lib/math/generic/sqrt.c

@@ -92 +92 @@
 #include "internal.h"
 
-static const double tiny = 1.0e-300;
+static  const double    one     = 1.0, tiny=1.0e-300;
 
 double sqrt(double x)
@@ -101 +101 @@
         uint32_t r,t1,s1,ix1,q1;
 
-        EXTRACT_WORDS(ix0, ix1, x);
-
-        /* take care of Inf and NaN */
-        if ((ix0&0x7ff00000) == 0x7ff00000) {
-                return x*x + x;  /* sqrt(NaN)=NaN, sqrt(+inf)=+inf, sqrt(-inf)=sNaN */
-        }
-        /* take care of zero */
-        if (ix0 <= 0) {
-                if (((ix0&~sign)|ix1) == 0)
-                        return x;  /* sqrt(+-0) = +-0 */
-                if (ix0 < 0)
-                        return (x-x)/(x-x);  /* sqrt(-ve) = sNaN */
-        }
-        /* normalize x */
-        m = ix0>>20;
-        if (m == 0) {  /* subnormal x */
-                while (ix0 == 0) {
-                        m -= 21;
-                        ix0 |= (ix1>>11);
-                        ix1 <<= 21;
-                }
-                for (i=0; (ix0&0x00100000) == 0; i++)
-                        ix0<<=1;
-                m -= i - 1;
-                ix0 |= ix1>>(32-i);
-                ix1 <<= i;
-        }
-        m -= 1023;    /* unbias exponent */
+        EXTRACT_WORDS(ix0,ix1,x);
+
+    /* take care of Inf and NaN */
+        if((ix0&0x7ff00000)==0x7ff00000) {                      
+            return x*x+x;               /* sqrt(NaN)=NaN, sqrt(+inf)=+inf
+                                           sqrt(-inf)=sNaN */
+        } 
+    /* take care of zero */
+        if(ix0<=0) {
+            if(((ix0&(~sign))|ix1)==0) return x;/* sqrt(+-0) = +-0 */
+            else if(ix0<0)
+                return (x-x)/(x-x);             /* sqrt(-ve) = sNaN */
+        }
+    /* normalize x */
+        m = (ix0>>20);
+        if(m==0) {                              /* subnormal x */
+            while(ix0==0) {
+                m -= 21;
+                ix0 |= (ix1>>11); ix1 <<= 21;
+            }
+            for(i=0;(ix0&0x00100000)==0;i++) ix0<<=1;
+            m -= i-1;
+            ix0 |= (ix1>>(32-i));
+            ix1 <<= i;
+        }
+        m -= 1023;      /* unbias exponent */
         ix0 = (ix0&0x000fffff)|0x00100000;
-        if (m & 1) {  /* odd m, double x to make it even */
-                ix0 += ix0 + ((ix1&sign)>>31);
-                ix1 += ix1;
-        }
-        m >>= 1;      /* m = [m/2] */
-
-        /* generate sqrt(x) bit by bit */
+        if(m&1){        /* odd m, double x to make it even */
+            ix0 += ix0 + ((ix1&sign)>>31);
+            ix1 += ix1;
+        }
+        m >>= 1;        /* m = [m/2] */
+
+    /* generate sqrt(x) bit by bit */
         ix0 += ix0 + ((ix1&sign)>>31);
         ix1 += ix1;
-        q = q1 = s0 = s1 = 0;  /* [q,q1] = sqrt(x) */
-        r = 0x00200000;        /* r = moving bit from right to left */
-
-        while (r != 0) {
-                t = s0 + r;
-                if (t <= ix0) {
-                        s0   = t + r;
-                        ix0 -= t;
-                        q   += r;
-                }
-                ix0 += ix0 + ((ix1&sign)>>31);
-                ix1 += ix1;
-                r >>= 1;
+        q = q1 = s0 = s1 = 0;   /* [q,q1] = sqrt(x) */
+        r = 0x00200000;         /* r = moving bit from right to left */
+
+        while(r!=0) {
+            t = s0+r; 
+            if(t<=ix0) { 
+                s0   = t+r; 
+                ix0 -= t; 
+                q   += r; 
+            } 
+            ix0 += ix0 + ((ix1&sign)>>31);
+            ix1 += ix1;
+            r>>=1;
         }
 
         r = sign;
-        while (r != 0) {
-                t1 = s1 + r;
-                t  = s0;
-                if (t < ix0 || (t == ix0 && t1 <= ix1)) {
-                        s1 = t1 + r;
-                        if ((t1&sign) == (uint32_t)sign && (s1&sign) == 0)
-                                s0++;
-                        ix0 -= t;
-                        if (ix1 < t1)
-                                ix0--;
-                        ix1 -= t1;
-                        q1 += r;
-                }
-                ix0 += ix0 + ((ix1&sign)>>31);
-                ix1 += ix1;
-                r >>= 1;
-        }
-
-        /* use floating add to find out rounding direction */
-        if ((ix0|ix1) != 0) {
-                z = 1.0 - tiny; /* raise inexact flag */
-                if (z >= 1.0) {
-                        z = 1.0 + tiny;
-                        if (q1 == (uint32_t)0xffffffff) {
-                                q1 = 0;
-                                q++;
-                        } else if (z > 1.0) {
-                                if (q1 == (uint32_t)0xfffffffe)
-                                        q++;
-                                q1 += 2;
-                        } else
-                                q1 += q1 & 1;
-                }
-        }
-        ix0 = (q>>1) + 0x3fe00000;
-        ix1 = q1>>1;
-        if (q&1)
-                ix1 |= sign;
-        ix0 += m << 20;
-        INSERT_WORDS(z, ix0, ix1);
+        while(r!=0) {
+            t1 = s1+r; 
+            t  = s0;
+            if((t<ix0)||((t==ix0)&&(t1<=ix1))) { 
+                s1  = t1+r;
+                if(((t1&sign)==sign)&&(s1&sign)==0) s0 += 1;
+                ix0 -= t;
+                if (ix1 < t1) ix0 -= 1;
+                ix1 -= t1;
+                q1  += r;
+            }
+            ix0 += ix0 + ((ix1&sign)>>31);
+            ix1 += ix1;
+            r>>=1;
+        }
+
+    /* use floating add to find out rounding direction */
+        if((ix0|ix1)!=0) {
+            z = one-tiny; /* trigger inexact flag */
+            if (z>=one) {
+                z = one+tiny;
+                if (q1==(uint32_t)0xffffffff) { q1=0; q += 1;}
+                else if (z>one) {
+                    if (q1==(uint32_t)0xfffffffe) q+=1;
+                    q1+=2; 
+                } else
+                    q1 += (q1&1);
+            }
+        }
+        ix0 = (q>>1)+0x3fe00000;
+        ix1 =  q1>>1;
+        if ((q&1)==1) ix1 |= sign;
+        ix0 += (m <<20);
+        INSERT_WORDS(z,ix0,ix1);
         return z;
 }