Fix 695467: Add and use fz_ftoa function (like dtoa but with floats).

The dtoa function is for doubles (which is what MuJS uses) but for MuPDF
we only need and want float precision in our output formatting.

1 files changed, 327 insertions, 0 deletions

diff --git a/source/fitz/ftoa.c b/source/fitz/ftoa.c
new file mode 100644
index 00000000..dc3ce73b
--- /dev/null
+++ b/source/fitz/ftoa.c
@@ -0,0 +1,327 @@
+/* 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 "mupdf/fitz.h"
+
+#include <stdio.h>
+#include <math.h>
+#include <float.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#ifndef INFINITY
+#define INFINITY (DBL_MAX+DBL_MAX)
+#endif
+#ifndef NAN
+#define NAN (INFINITY-INFINITY)
+#endif
+
+typedef unsigned long ulong;
+
+enum { NSIGNIF	= 9 };
+
+/*
+ * first few powers of 10
+ */
+static float 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,
+};
+#define	npows10 ((int)(sizeof(pows10)/sizeof(pows10[0])))
+#define	pow10(x) fmtpow10(x)
+
+static float
+pow10(int n)
+{
+	float 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.
+	 */
+	return 0;
+}
+
+/*
+ * format exponent like sprintf(p, "e%+d", e)
+ */
+static void
+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
+fz_ftoa(float f, char *s, int *exp, int *neg, int *ns)
+{
+	int c, d, e2, e, ee, i, ndigit, oerrno;
+	char tmp[NSIGNIF+10];
+	float 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.
+	 */
+	frexpf(f, &e2);
+	e = (int)(e2 * .301029995664f);
+	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;
+	fmtexp(s+NSIGNIF, e);
+
+	/*
+	 * adjust conversion until strtod(s) == f exactly.
+	 */
+	for(i=0; i<10; i++) {
+		g = fz_strtod(s, NULL);
+		if(f > g) {
+			if(xadd1(s, NSIGNIF)) {
+				/* gained a digit */
+				e--;
+				fmtexp(s+NSIGNIF, e);
+			}
+			continue;
+		}
+		if(f < g) {
+			if(xsub1(s, NSIGNIF)) {
+				/* lost a digit */
+				e++;
+				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 = fz_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--;
+			fmtexp(tmp+NSIGNIF, ee);
+		}
+		g = fz_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 = fz_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;
+}