Some modifications to improve floating point printing

diff --git a/lang/cem/libcc.ansi/stdlib/ext_comp.c b/lang/cem/libcc.ansi/stdlib/ext_comp.c
index 0cbbdc6..e4117c3 100644 (file)
--- a/lang/cem/libcc.ansi/stdlib/ext_comp.c
+++ b/lang/cem/libcc.ansi/stdlib/ext_comp.c
@@ -538,7 +538,18 @@ _str_ext_cvt(const char *s, char **ss, struct EXTEND *e)
 
 #include       <math.h>
 
+static
+ten_mult(struct EXTEND *e)
+{
+       struct EXTEND e1 = *e;
+
+       e1.exp++;
+       e->exp += 3;
+       add_ext(e, &e1, e);
+}
+
 #define NDIGITS 128
+#define NSIGNIFICANT 19
 
 char *
 _ext_str_cvt(struct EXTEND *e, int ndigit, int *decpt, int *sign, int ecvtflag)
@@ -546,6 +557,7 @@ _ext_str_cvt(struct EXTEND *e, int ndigit, int *decpt, int *sign, int ecvtflag)
        /*      Like cvt(), but for extended precision */
 
        static char buf[NDIGITS+1];
+       struct EXTEND m;
        register char *p = buf;
        register char *pe;
        int findex = 0;
@@ -584,7 +596,7 @@ _ext_str_cvt(struct EXTEND *e, int ndigit, int *decpt, int *sign, int ecvtflag)
                        mul_ext(e, &big_ten_powers[findex], e);
                        *decpt -= findex * TP;
                        /* here, value >= 10 ** -28 */
-                       mul_ext(e, &ten_powers[1], e);
+                       ten_mult(e);
                        (*decpt)--;
                        pp = &r_ten_powers[0];
                        while(cmp_ext(e, pp) < 0) pp++;
@@ -600,7 +612,17 @@ _ext_str_cvt(struct EXTEND *e, int ndigit, int *decpt, int *sign, int ecvtflag)
                pe += *decpt;
                if (pe > &buf[NDIGITS]) pe = &buf[NDIGITS];
        }
+       m.exp = -62;
+       m.sign = 0;
+       m.m1 = 0xA0000000;
+       m.m2 = 0;
        while (p <= pe) {
+               struct EXTEND oneminm;
+
+               if (p - pe > NSIGNIFICANT) {
+                       findex = 0;
+                       e->m1 = 0;
+               }
                if (findex) {
                        struct EXTEND tc, oldtc;
                        int count = 0;
@@ -621,20 +643,31 @@ _ext_str_cvt(struct EXTEND *e, int ndigit, int *decpt, int *sign, int ecvtflag)
                        findex--;
                        continue;
                }
-               if (e->exp >= 0 && e->m1 != 0) {
-                       struct EXTEND x;
-
-                       x.m2 = 0; x.exp = e->exp;
-                       x.sign = 1;
-                       x.m1 = e->m1>>(31-e->exp);
-                       *p++ = (x.m1) + '0';
-                       if (x.m1) {
+               if (e->m1) {
+                       m.sign = 1;
+                       add_ext(&ten_powers[0], &m, &oneminm);
+                       m.sign = 0;
+                       if (e->exp >= 0) {
+                               struct EXTEND x;
+
+                               x.m2 = 0; x.exp = e->exp;
+                               x.sign = 1;
+                               x.m1 = e->m1>>(31-e->exp);
+                               *p++ = (x.m1) + '0';
                                x.m1 = x.m1 << (31-e->exp);
                                add_ext(e, &x, e);
                        }
+                       else *p++ = '0';
+                       /* Check that remainder is still significant */
+                       if (cmp_ext(&m, e) > 0 || cmp_ext(e, &oneminm) > 0) {
+                               e->m1 = 0;
+                               if (e->exp >= -1) *(p-1) += 1;
+                               continue;
+                       }
+                       ten_mult(&m);
+                       ten_mult(e);
                }
                else *p++ = '0';
-               if (e->m1) mul_ext(e, &ten_powers[1], e);
        }
        if (pe >= buf) {
                p = pe;
@@ -670,18 +703,11 @@ _dbl_ext_cvt(double value, struct EXTEND *e)
        e->sign = value < 0.0;
        if (e->sign) value = -value;
        e->exp = exponent - 1;
-       e->m1 = 0;
-       e->m2 = 0;
-       for (i = 64; i > 0 && value != 0; i--) {
-               double ipart;
-
-               b64_sft(&(e->mantissa),-1);
-               value = modf(2.0*value, &ipart);
-               if (ipart) {
-                       e->m2 |= 1;
-               }
-       }
-       if (i > 0) b64_sft(&(e->mantissa),-i);
+       value *= 4294967296.0;
+       e->m1 = value;
+       value -= e->m1;
+       value *= 4294967296.0;
+       e->m2 = value;
 }
 
 static struct EXTEND max_d;
@@ -705,7 +731,7 @@ _ext_dbl_cvt(struct EXTEND *e)
                f = HUGE_VAL;
                errno = ERANGE;
        }
-       else    f = ldexp(ldexp((double)e->m1, 32) + (double)e->m2, e->exp-63);
+       else    f = ldexp((double)e->m1*4294967296.0 + (double)e->m2, e->exp-63);
        if (sign) f = -f;
        if (f == 0.0 && (e->m1 != 0 || e->m2 != 0)) {
                errno = ERANGE;