ref: 83dd92f0856c30beffcb04e7e6fc28ea225fdac5
parent: 375c8a8e08d84b66d8daf0ab211ceea49ee7b9ef
author: Tor Andersson <[email protected]>
date: Tue Mar 18 11:38:35 EDT 2014
Add and use dtoa function from plan9/libfmt.
--- /dev/null
+++ b/jsdtoa.c
@@ -1,0 +1,329 @@
+/* The authors of this software are Rob Pike and Ken Thompson.
+ * Copyright (c) 2002 by Lucent Technologies.
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose without fee is hereby granted, provided that this entire notice
+ * is included in all copies of any software which is or includes a copy
+ * or modification of this software and in all copies of the supporting
+ * documentation for such software.
+ * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
+ * WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
+ * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
+ * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
+ */
+
+#include <stdio.h>
+#include <math.h>
+#include <float.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+
+enum { NSIGNIF = 17 };+
+/*
+ * first few powers of 10, enough for about 1/2 of the
+ * total space for doubles.
+ */
+static double pows10[] =
+{+ 1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
+ 1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19,
+ 1e20, 1e21, 1e22, 1e23, 1e24, 1e25, 1e26, 1e27, 1e28, 1e29,
+ 1e30, 1e31, 1e32, 1e33, 1e34, 1e35, 1e36, 1e37, 1e38, 1e39,
+ 1e40, 1e41, 1e42, 1e43, 1e44, 1e45, 1e46, 1e47, 1e48, 1e49,
+ 1e50, 1e51, 1e52, 1e53, 1e54, 1e55, 1e56, 1e57, 1e58, 1e59,
+ 1e60, 1e61, 1e62, 1e63, 1e64, 1e65, 1e66, 1e67, 1e68, 1e69,
+ 1e70, 1e71, 1e72, 1e73, 1e74, 1e75, 1e76, 1e77, 1e78, 1e79,
+ 1e80, 1e81, 1e82, 1e83, 1e84, 1e85, 1e86, 1e87, 1e88, 1e89,
+ 1e90, 1e91, 1e92, 1e93, 1e94, 1e95, 1e96, 1e97, 1e98, 1e99,
+ 1e100, 1e101, 1e102, 1e103, 1e104, 1e105, 1e106, 1e107, 1e108, 1e109,
+ 1e110, 1e111, 1e112, 1e113, 1e114, 1e115, 1e116, 1e117, 1e118, 1e119,
+ 1e120, 1e121, 1e122, 1e123, 1e124, 1e125, 1e126, 1e127, 1e128, 1e129,
+ 1e130, 1e131, 1e132, 1e133, 1e134, 1e135, 1e136, 1e137, 1e138, 1e139,
+ 1e140, 1e141, 1e142, 1e143, 1e144, 1e145, 1e146, 1e147, 1e148, 1e149,
+ 1e150, 1e151, 1e152, 1e153, 1e154, 1e155, 1e156, 1e157, 1e158, 1e159,
+};
+#define npows10 ((int)(sizeof(pows10)/sizeof(pows10[0])))
+#define pow10(x) fmtpow10(x)
+
+static double
+pow10(int n)
+{+ double d;
+ int neg;
+
+ neg = 0;
+ if(n < 0){+ neg = 1;
+ n = -n;
+ }
+
+ if(n < npows10)
+ d = pows10[n];
+ else{+ d = pows10[npows10-1];
+ for(;;){+ n -= npows10 - 1;
+ if(n < npows10){+ d *= pows10[n];
+ break;
+ }
+ d *= pows10[npows10 - 1];
+ }
+ }
+ if(neg)
+ return 1./d;
+ return d;
+}
+
+/*
+ * add 1 to the decimal integer string a of length n.
+ * if 99999 overflows into 10000, return 1 to tell caller
+ * to move the virtual decimal point.
+ */
+static int
+xadd1(char *a, int n)
+{+ char *b;
+ int c;
+
+ if(n < 0 || n > NSIGNIF)
+ return 0;
+ for(b = a+n-1; b >= a; b--) {+ c = *b + 1;
+ if(c <= '9') {+ *b = c;
+ return 0;
+ }
+ *b = '0';
+ }
+ /*
+ * need to overflow adding digit.
+ * shift number down and insert 1 at beginning.
+ * decimal is known to be 0s or we wouldn't
+ * have gotten this far. (e.g., 99999+1 => 00000)
+ */
+ a[0] = '1';
+ return 1;
+}
+
+/*
+ * subtract 1 from the decimal integer string a.
+ * if 10000 underflows into 09999, make it 99999
+ * and return 1 to tell caller to move the virtual
+ * decimal point. this way, xsub1 is inverse of xadd1.
+ */
+static int
+xsub1(char *a, int n)
+{+ char *b;
+ int c;
+
+ if(n < 0 || n > NSIGNIF)
+ return 0;
+ for(b = a+n-1; b >= a; b--) {+ c = *b - 1;
+ if(c >= '0') {+ if(c == '0' && b == a) {+ /*
+ * just zeroed the top digit; shift everyone up.
+ * decimal is known to be 9s or we wouldn't
+ * have gotten this far. (e.g., 10000-1 => 09999)
+ */
+ *b = '9';
+ return 1;
+ }
+ *b = c;
+ return 0;
+ }
+ *b = '9';
+ }
+ /*
+ * can't get here. the number a is always normalized
+ * so that it has a nonzero first digit.
+ */
+ abort();
+}
+
+/*
+ * format exponent like sprintf(p, "e%+d", e)
+ */
+void
+jsV_fmtexp(char *p, int e)
+{+ char se[9];
+ int i;
+
+ *p++ = 'e';
+ if(e < 0) {+ *p++ = '-';
+ e = -e;
+ } else
+ *p++ = '+';
+ i = 0;
+ while(e) {+ se[i++] = e % 10 + '0';
+ e /= 10;
+ }
+ while(i < 1)
+ se[i++] = '0';
+ while(i > 0)
+ *p++ = se[--i];
+ *p++ = '\0';
+}
+
+/*
+ * compute decimal integer m, exp such that:
+ * f = m*10^exp
+ * m is as short as possible with losing exactness
+ * assumes special cases (NaN, +Inf, -Inf) have been handled.
+ */
+void
+jsV_dtoa(double f, char *s, int *exp, int *neg, int *ns)
+{+ int c, d, e2, e, ee, i, ndigit, oerrno;
+ char tmp[NSIGNIF+10];
+ double g;
+
+ oerrno = errno; /* in case strtod smashes errno */
+
+ /*
+ * make f non-negative.
+ */
+ *neg = 0;
+ if(f < 0) {+ f = -f;
+ *neg = 1;
+ }
+
+ /*
+ * must handle zero specially.
+ */
+ if(f == 0){+ *exp = 0;
+ s[0] = '0';
+ s[1] = '\0';
+ *ns = 1;
+ return;
+ }
+
+ /*
+ * find g,e such that f = g*10^e.
+ * guess 10-exponent using 2-exponent, then fine tune.
+ */
+ frexp(f, &e2);
+ e = (int)(e2 * .301029995664);
+ g = f * pow10(-e);
+ while(g < 1) {+ e--;
+ g = f * pow10(-e);
+ }
+ while(g >= 10) {+ e++;
+ g = f * pow10(-e);
+ }
+
+ /*
+ * convert NSIGNIF digits as a first approximation.
+ */
+ for(i=0; i<NSIGNIF; i++) {+ d = (int)g;
+ s[i] = d+'0';
+ g = (g-d) * 10;
+ }
+ s[i] = 0;
+
+ /*
+ * adjust e because s is 314159... not 3.14159...
+ */
+ e -= NSIGNIF-1;
+ jsV_fmtexp(s+NSIGNIF, e);
+
+ /*
+ * adjust conversion until strtod(s) == f exactly.
+ */
+ for(i=0; i<10; i++) {+ g = strtod(s, NULL);
+ if(f > g) {+ if(xadd1(s, NSIGNIF)) {+ /* gained a digit */
+ e--;
+ jsV_fmtexp(s+NSIGNIF, e);
+ }
+ continue;
+ }
+ if(f < g) {+ if(xsub1(s, NSIGNIF)) {+ /* lost a digit */
+ e++;
+ jsV_fmtexp(s+NSIGNIF, e);
+ }
+ continue;
+ }
+ break;
+ }
+
+ /*
+ * play with the decimal to try to simplify.
+ */
+
+ /*
+ * bump last few digits up to 9 if we can
+ */
+ for(i=NSIGNIF-1; i>=NSIGNIF-3; i--) {+ c = s[i];
+ if(c != '9') {+ s[i] = '9';
+ g = strtod(s, NULL);
+ if(g != f) {+ s[i] = c;
+ break;
+ }
+ }
+ }
+
+ /*
+ * add 1 in hopes of turning 9s to 0s
+ */
+ if(s[NSIGNIF-1] == '9') {+ strcpy(tmp, s);
+ ee = e;
+ if(xadd1(tmp, NSIGNIF)) {+ ee--;
+ jsV_fmtexp(tmp+NSIGNIF, ee);
+ }
+ g = strtod(tmp, NULL);
+ if(g == f) {+ strcpy(s, tmp);
+ e = ee;
+ }
+ }
+
+ /*
+ * bump last few digits down to 0 as we can.
+ */
+ for(i=NSIGNIF-1; i>=NSIGNIF-3; i--) {+ c = s[i];
+ if(c != '0') {+ s[i] = '0';
+ g = strtod(s, NULL);
+ if(g != f) {+ s[i] = c;
+ break;
+ }
+ }
+ }
+
+ /*
+ * remove trailing zeros.
+ */
+ ndigit = NSIGNIF;
+ while(ndigit > 1 && s[ndigit-1] == '0'){+ e++;
+ --ndigit;
+ }
+ s[ndigit] = 0;
+ *exp = e;
+ *ns = ndigit;
+ errno = oerrno;
+}
--- a/jsnumber.c
+++ b/jsnumber.c
@@ -34,12 +34,19 @@
/* Customized ToString() on a number */
void numtostr(js_State *J, const char *fmt, int w, double n)
{- char buf[40];
+ char buf[32], *e;
if (isnan(n)) js_pushliteral(J, "NaN");
else if (isinf(n)) js_pushliteral(J, n < 0 ? "-Infinity" : "Infinity");
else if (n == 0) js_pushliteral(J, "0");
else {+ if (w < 1) w = 1;
+ if (w > 17) w = 17;
sprintf(buf, fmt, w, n);
+ e = strchr(buf, 'e');
+ if (e) {+ int exp = atoi(e+1);
+ sprintf(e, "e%+d", exp);
+ }
js_pushstring(J, buf);
}
}
--- a/jsvalue.c
+++ b/jsvalue.c
@@ -104,6 +104,7 @@
return vv;
}
}
+
js_typeerror(J, "cannot convert object to primitive");
}
@@ -187,13 +188,53 @@
}
/* ToString() on a number */
-const char *jsV_numbertostring(js_State *J, double n)
+const char *jsV_numbertostring(js_State *J, double f)
{- char buf[32];
- if (isnan(n)) return "NaN";
- if (isinf(n)) return n < 0 ? "-Infinity" : "Infinity";
- if (n == 0) return "0";
- sprintf(buf, "%.17g", n); /* DBL_DECIMAL_DIG == 17 */
+ char buf[32], digits[32], *p = buf, *s = digits;
+ int exp, neg, ndigits, point;
+
+ if (isnan(f)) return "NaN";
+ if (isinf(f)) return f < 0 ? "-Infinity" : "Infinity";
+ if (f == 0) return "0";
+
+ jsV_dtoa(f, digits, &exp, &neg, &ndigits);
+ point = ndigits + exp;
+
+ if (neg)
+ *p++ = '-';
+
+ if (point < -5 || point > 21) {+ *p++ = *s++;
+ if (ndigits > 1) {+ int n = ndigits - 1;
+ *p++ = '.';
+ while (n--)
+ *p++ = *s++;
+ }
+ jsV_fmtexp(p, point - 1);
+ }
+
+ else if (point <= 0) {+ *p++ = '0';
+ *p++ = '.';
+ while (point++ < 0)
+ *p++ = '0';
+ while (ndigits-- > 0)
+ *p++ = *s++;
+ *p = 0;
+ }
+
+ else {+ while (ndigits-- > 0) {+ *p++ = *s++;
+ if (--point == 0 && ndigits > 0)
+ *p++ = '.';
+ }
+ while (point-- > 0)
+ *p++ = '0';
+ *p = 0;
+ }
+
return js_intern(J, buf);
}
--- a/jsvalue.h
+++ b/jsvalue.h
@@ -132,6 +132,10 @@
const char *jsV_numbertostring(js_State *J, double number);
double jsV_stringtonumber(js_State *J, const char *string);
+/* jsdtoa.c */
+void jsV_fmtexp(char *p, int e);
+void jsV_dtoa(double f, char *digits, int *exp, int *neg, int *ndigits);
+
/* jsproperty.c */
js_Object *jsV_newobject(js_State *J, enum js_Class type, js_Object *prototype);
js_Property *jsV_getownproperty(js_State *J, js_Object *obj, const char *name);
--- a/one.c
+++ b/one.c
@@ -3,6 +3,7 @@
#include "jsbuiltin.c"
#include "jscompile.c"
#include "jsdate.c"
+#include "jsdtoa.c"
#include "jsdump.c"
#include "jserror.c"
#include "jsfunction.c"