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Add and use dtoa function from plan9/libfmt.
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Lines changed: 389 additions & 7 deletions

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‎jsdtoa.c‎

Lines changed: 329 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,329 @@
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/* The authors of this software are Rob Pike and Ken Thompson.
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* Copyright (c) 2002 by Lucent Technologies.
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* Permission to use, copy, modify, and distribute this software for any
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* purpose without fee is hereby granted, provided that this entire notice
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* is included in all copies of any software which is or includes a copy
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* or modification of this software and in all copies of the supporting
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* documentation for such software.
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* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
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* WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
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* REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
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* OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
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*/
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#include <stdio.h>
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#include <math.h>
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#include <float.h>
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#include <string.h>
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#include <stdlib.h>
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#include <errno.h>
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enum { NSIGNIF = 17 };
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/*
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* first few powers of 10, enough for about 1/2 of the
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* total space for doubles.
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*/
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static double pows10[] =
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{
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1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
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1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19,
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1e20, 1e21, 1e22, 1e23, 1e24, 1e25, 1e26, 1e27, 1e28, 1e29,
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1e30, 1e31, 1e32, 1e33, 1e34, 1e35, 1e36, 1e37, 1e38, 1e39,
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1e40, 1e41, 1e42, 1e43, 1e44, 1e45, 1e46, 1e47, 1e48, 1e49,
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1e50, 1e51, 1e52, 1e53, 1e54, 1e55, 1e56, 1e57, 1e58, 1e59,
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1e60, 1e61, 1e62, 1e63, 1e64, 1e65, 1e66, 1e67, 1e68, 1e69,
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1e70, 1e71, 1e72, 1e73, 1e74, 1e75, 1e76, 1e77, 1e78, 1e79,
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1e80, 1e81, 1e82, 1e83, 1e84, 1e85, 1e86, 1e87, 1e88, 1e89,
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1e90, 1e91, 1e92, 1e93, 1e94, 1e95, 1e96, 1e97, 1e98, 1e99,
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1e100, 1e101, 1e102, 1e103, 1e104, 1e105, 1e106, 1e107, 1e108, 1e109,
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1e110, 1e111, 1e112, 1e113, 1e114, 1e115, 1e116, 1e117, 1e118, 1e119,
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1e120, 1e121, 1e122, 1e123, 1e124, 1e125, 1e126, 1e127, 1e128, 1e129,
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1e130, 1e131, 1e132, 1e133, 1e134, 1e135, 1e136, 1e137, 1e138, 1e139,
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1e140, 1e141, 1e142, 1e143, 1e144, 1e145, 1e146, 1e147, 1e148, 1e149,
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1e150, 1e151, 1e152, 1e153, 1e154, 1e155, 1e156, 1e157, 1e158, 1e159,
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};
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#define npows10 ((int)(sizeof(pows10)/sizeof(pows10[0])))
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#define pow10(x) fmtpow10(x)
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static double
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pow10(int n)
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{
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double d;
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int neg;
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neg = 0;
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if(n < 0){
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neg = 1;
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n = -n;
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}
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if(n < npows10)
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d = pows10[n];
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else{
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d = pows10[npows10-1];
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for(;;){
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n -= npows10 - 1;
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if(n < npows10){
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d *= pows10[n];
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break;
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}
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d *= pows10[npows10 - 1];
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}
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}
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if(neg)
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return 1./d;
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return d;
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}
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/*
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* add 1 to the decimal integer string a of length n.
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* if 99999 overflows into 10000, return 1 to tell caller
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* to move the virtual decimal point.
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*/
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static int
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xadd1(char *a, int n)
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{
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char *b;
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int c;
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if(n < 0 || n > NSIGNIF)
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return 0;
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for(b = a+n-1; b >= a; b--) {
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c = *b + 1;
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if(c <= '9') {
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*b = c;
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return 0;
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}
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*b = '0';
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}
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/*
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* need to overflow adding digit.
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* shift number down and insert 1 at beginning.
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* decimal is known to be 0s or we wouldn't
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* have gotten this far. (e.g., 99999+1 => 00000)
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*/
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a[0] = '1';
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return 1;
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}
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/*
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* subtract 1 from the decimal integer string a.
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* if 10000 underflows into 09999, make it 99999
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* and return 1 to tell caller to move the virtual
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* decimal point. this way, xsub1 is inverse of xadd1.
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*/
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static int
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xsub1(char *a, int n)
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{
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char *b;
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int c;
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if(n < 0 || n > NSIGNIF)
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return 0;
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for(b = a+n-1; b >= a; b--) {
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c = *b - 1;
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if(c >= '0') {
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if(c == '0' && b == a) {
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/*
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* just zeroed the top digit; shift everyone up.
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* decimal is known to be 9s or we wouldn't
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* have gotten this far. (e.g., 10000-1 => 09999)
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*/
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*b = '9';
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return 1;
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}
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*b = c;
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return 0;
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}
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*b = '9';
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}
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/*
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* can't get here. the number a is always normalized
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* so that it has a nonzero first digit.
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*/
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abort();
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}
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/*
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* format exponent like sprintf(p, "e%+d", e)
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*/
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void
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jsV_fmtexp(char *p, int e)
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{
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char se[9];
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int i;
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*p++ = 'e';
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if(e < 0) {
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*p++ = '-';
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e = -e;
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} else
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*p++ = '+';
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i = 0;
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while(e) {
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se[i++] = e % 10 + '0';
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e /= 10;
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}
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while(i < 1)
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se[i++] = '0';
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while(i > 0)
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*p++ = se[--i];
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*p++ = '\0';
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}
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/*
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* compute decimal integer m, exp such that:
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* f = m*10^exp
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* m is as short as possible with losing exactness
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* assumes special cases (NaN, +Inf, -Inf) have been handled.
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*/
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void
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jsV_dtoa(double f, char *s, int *exp, int *neg, int *ns)
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{
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int c, d, e2, e, ee, i, ndigit, oerrno;
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char tmp[NSIGNIF+10];
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double g;
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oerrno = errno; /* in case strtod smashes errno */
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/*
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* make f non-negative.
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*/
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*neg = 0;
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if(f < 0) {
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f = -f;
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*neg = 1;
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}
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/*
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* must handle zero specially.
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*/
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if(f == 0){
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*exp = 0;
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s[0] = '0';
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s[1] = '\0';
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*ns = 1;
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return;
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}
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/*
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* find g,e such that f = g*10^e.
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* guess 10-exponent using 2-exponent, then fine tune.
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*/
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frexp(f, &e2);
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e = (int)(e2 * .301029995664);
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g = f * pow10(-e);
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while(g < 1) {
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e--;
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g = f * pow10(-e);
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}
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while(g >= 10) {
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e++;
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g = f * pow10(-e);
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}
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/*
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* convert NSIGNIF digits as a first approximation.
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*/
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for(i=0; i<NSIGNIF; i++) {
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d = (int)g;
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s[i] = d+'0';
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g = (g-d) * 10;
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}
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s[i] = 0;
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/*
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* adjust e because s is 314159... not 3.14159...
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*/
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e -= NSIGNIF-1;
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jsV_fmtexp(s+NSIGNIF, e);
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/*
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* adjust conversion until strtod(s) == f exactly.
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*/
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for(i=0; i<10; i++) {
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g = strtod(s, NULL);
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if(f > g) {
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if(xadd1(s, NSIGNIF)) {
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/* gained a digit */
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e--;
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jsV_fmtexp(s+NSIGNIF, e);
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}
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continue;
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}
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if(f < g) {
256+
if(xsub1(s, NSIGNIF)) {
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/* lost a digit */
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e++;
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jsV_fmtexp(s+NSIGNIF, e);
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}
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continue;
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}
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break;
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}
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/*
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* play with the decimal to try to simplify.
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*/
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/*
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* bump last few digits up to 9 if we can
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*/
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for(i=NSIGNIF-1; i>=NSIGNIF-3; i--) {
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c = s[i];
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if(c != '9') {
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s[i] = '9';
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g = strtod(s, NULL);
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if(g != f) {
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s[i] = c;
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break;
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}
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}
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}
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/*
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* add 1 in hopes of turning 9s to 0s
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*/
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if(s[NSIGNIF-1] == '9') {
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strcpy(tmp, s);
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ee = e;
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if(xadd1(tmp, NSIGNIF)) {
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ee--;
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jsV_fmtexp(tmp+NSIGNIF, ee);
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}
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g = strtod(tmp, NULL);
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if(g == f) {
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strcpy(s, tmp);
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e = ee;
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}
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}
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/*
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* bump last few digits down to 0 as we can.
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*/
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for(i=NSIGNIF-1; i>=NSIGNIF-3; i--) {
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c = s[i];
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if(c != '0') {
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s[i] = '0';
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g = strtod(s, NULL);
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if(g != f) {
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s[i] = c;
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break;
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}
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}
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}
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/*
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* remove trailing zeros.
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*/
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ndigit = NSIGNIF;
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while(ndigit > 1 && s[ndigit-1] == '0'){
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e++;
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--ndigit;
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}
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s[ndigit] = 0;
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*exp = e;
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*ns = ndigit;
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errno = oerrno;
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}

‎jsnumber.c‎

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -34,12 +34,19 @@ static void Np_toString(js_State *J)
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/* Customized ToString() on a number */
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void numtostr(js_State *J, const char *fmt, int w, double n)
3636
{
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char buf[40];
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char buf[32], *e;
3838
if (isnan(n)) js_pushliteral(J, "NaN");
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else if (isinf(n)) js_pushliteral(J, n < 0 ? "-Infinity" : "Infinity");
4040
else if (n == 0) js_pushliteral(J, "0");
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else {
42+
if (w < 1) w = 1;
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if (w > 17) w = 17;
4244
sprintf(buf, fmt, w, n);
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e = strchr(buf, 'e');
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if (e) {
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int exp = atoi(e+1);
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sprintf(e, "e%+d", exp);
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}
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js_pushstring(J, buf);
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}
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}

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