9base

fltfmt.c (12850B)

---

 /* Copyright (c) 2002-2006 Lucent Technologies; see LICENSE */
 #include <stdio.h>
 #include <math.h>
 #include <float.h>
 #include <string.h>
 #include <stdlib.h>
 #include <errno.h>
 #include <stdarg.h>
 #include <fmt.h>
 #include <assert.h>
 #include "plan9.h"
 #include "fmt.h"
 #include "fmtdef.h"
 #include "nan.h"
 
 enum
 {
 	FDIGIT	= 30,
 	FDEFLT	= 6,
 	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%+02d", e)
  */
 static void
 xfmtexp(char *p, int e, int ucase)
 {
 	char se[9];
 	int i;
 
 	*p++ = ucase ? 'E' : 'e';
 	if(e < 0) {
 		*p++ = '-';
 		e = -e;
 	} else
 		*p++ = '+';
 	i = 0;
 	while(e) {
 		se[i++] = e % 10 + '0';
 		e /= 10;
 	}
 	while(i < 2)
 		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.
  */
 static void
 xdtoa(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;
 	xfmtexp(s+NSIGNIF, e, 0);
 
 	/*
 	 * adjust conversion until strtod(s) == f exactly.
 	 */
 	for(i=0; i<10; i++) {
 		g = fmtstrtod(s, nil);
 		if(f > g) {
 			if(xadd1(s, NSIGNIF)) {
 				/* gained a digit */
 				e--;
 				xfmtexp(s+NSIGNIF, e, 0);
 			}
 			continue;
 		}
 		if(f < g) {
 			if(xsub1(s, NSIGNIF)) {
 				/* lost a digit */
 				e++;
 				xfmtexp(s+NSIGNIF, e, 0);
 			}
 			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 = fmtstrtod(s, nil);
 			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--;
 			xfmtexp(tmp+NSIGNIF, ee, 0);
 		}
 		g = fmtstrtod(tmp, nil);
 		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 = fmtstrtod(s, nil);
 			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;
 }
 
 #ifdef PLAN9PORT
 static char *special[] = { "NaN", "NaN", "+Inf", "+Inf", "-Inf", "-Inf" };
 #else
 static char *special[] = { "nan", "NAN", "inf", "INF", "-inf", "-INF" };
 #endif
 
 int
 __efgfmt(Fmt *fmt)
 {
 	char buf[NSIGNIF+10], *dot, *digits, *p, *s, suf[10], *t;
 	double f;
 	int c, chr, dotwid, e, exp, fl, ndigits, neg, newndigits;
 	int pad, point, prec, realchr, sign, sufwid, ucase, wid, z1, z2;
 	Rune r, *rs, *rt;
 	
 	if(fmt->flags&FmtLong)
 		f = va_arg(fmt->args, long double);
 	else
 		f = va_arg(fmt->args, double);
 	
 	/* 
 	 * extract formatting flags
 	 */
 	fl = fmt->flags;
 	fmt->flags = 0;
 	prec = FDEFLT;
 	if(fl & FmtPrec)
 		prec = fmt->prec;
 	chr = fmt->r;
 	ucase = 0;
 	switch(chr) {
 	case 'A':
 	case 'E':
 	case 'F':
 	case 'G':
 		chr += 'a'-'A';
 		ucase = 1;
 		break;
 	}
 
 	/*
 	 * pick off special numbers.
 	 */
 	if(__isNaN(f)) {
 		s = special[0+ucase];
 	special:
 		fmt->flags = fl & (FmtWidth|FmtLeft);
 		return __fmtcpy(fmt, s, strlen(s), strlen(s));
 	}
 	if(__isInf(f, 1)) {
 		s = special[2+ucase];
 		goto special;
 	}
 	if(__isInf(f, -1)) {
 		s = special[4+ucase];
 		goto special;
 	}
 
 	/*
 	 * get exact representation.
 	 */
 	digits = buf;
 	xdtoa(f, digits, &exp, &neg, &ndigits);
 
 	/*
 	 * get locale's decimal point.
 	 */
 	dot = fmt->decimal;
 	if(dot == nil)
 		dot = ".";
 	dotwid = utflen(dot);
 
 	/*
 	 * now the formatting fun begins.
 	 * compute parameters for actual fmt:
 	 *
 	 *	pad: number of spaces to insert before/after field.
 	 *	z1: number of zeros to insert before digits
 	 *	z2: number of zeros to insert after digits
 	 *	point: number of digits to print before decimal point
 	 *	ndigits: number of digits to use from digits[]
 	 *	suf: trailing suffix, like "e-5"
 	 */
 	realchr = chr;
 	switch(chr){
 	case 'g':
 		/*
 		 * convert to at most prec significant digits. (prec=0 means 1)
 		 */
 		if(prec == 0)
 			prec = 1;
 		if(ndigits > prec) {
 			if(digits[prec] >= '5' && xadd1(digits, prec))
 				exp++;
 			exp += ndigits-prec;
 			ndigits = prec;
 		}
 		
 		/*
 		 * extra rules for %g (implemented below):
 		 *	trailing zeros removed after decimal unless FmtSharp.
 		 *	decimal point only if digit follows.
 		 */
 
 		/* fall through to %e */
 	default:
 	case 'e':
 		/* 
 		 * one significant digit before decimal, no leading zeros.
 		 */
 		point = 1;
 		z1 = 0;
 		
 		/*
 		 * decimal point is after ndigits digits right now.
 		 * slide to be after first.
 		 */
 		e  = exp + (ndigits-1);
 
 		/*
 		 * if this is %g, check exponent and convert prec
 		 */
 		if(realchr == 'g') {
 			if(-4 <= e && e < prec)
 				goto casef;
 			prec--;	/* one digit before decimal; rest after */
 		}
 
 		/*
 		 * compute trailing zero padding or truncate digits.
 		 */
 		if(1+prec >= ndigits)
 			z2 = 1+prec - ndigits;
 		else {
 			/*
 			 * truncate digits
 			 */
 			assert(realchr != 'g');
 			newndigits = 1+prec;
 			if(digits[newndigits] >= '5' && xadd1(digits, newndigits)) {
 				/*
 				 * had 999e4, now have 100e5
 				 */
 				e++;
 			}
 			ndigits = newndigits;
 			z2 = 0;
 		}
 		xfmtexp(suf, e, ucase);
 		sufwid = strlen(suf);
 		break;
 
 	casef:
 	case 'f':
 		/*
 		 * determine where digits go with respect to decimal point
 		 */
 		if(ndigits+exp > 0) {
 			point = ndigits+exp;
 			z1 = 0;
 		} else {
 			point = 1;
 			z1 = 1 + -(ndigits+exp);
 		}
 
 		/*
 		 * %g specifies prec = number of significant digits
 		 * convert to number of digits after decimal point
 		 */
 		if(realchr == 'g')
 			prec += z1 - point;
 
 		/*
 		 * compute trailing zero padding or truncate digits.
 		 */
 		if(point+prec >= z1+ndigits)
 			z2 = point+prec - (z1+ndigits);
 		else {
 			/*
 			 * truncate digits
 			 */
 			assert(realchr != 'g');
 			newndigits = point+prec - z1;
 			if(newndigits < 0) {
 				z1 += newndigits;
 				newndigits = 0;
 			} else if(newndigits == 0) {
 				/* perhaps round up */
 				if(digits[0] >= '5'){
 					digits[0] = '1';
 					newndigits = 1;
 					goto newdigit;
 				}
 			} else if(digits[newndigits] >= '5' && xadd1(digits, newndigits)) {
 				/*
 				 * digits was 999, is now 100; make it 1000
 				 */
 				digits[newndigits++] = '0';
 			newdigit:
 				/*
 				 * account for new digit
 				 */
 				if(z1)	/* 0.099 => 0.100 or 0.99 => 1.00*/
 					z1--;
 				else	/* 9.99 => 10.00 */
 					point++;
 			}
 			z2 = 0;
 			ndigits = newndigits;
 		}	
 		sufwid = 0;
 		break;
 	}
 	
 	/*
 	 * if %g is given without FmtSharp, remove trailing zeros.
 	 * must do after truncation, so that e.g. print %.3g 1.001
 	 * produces 1, not 1.00.  sorry, but them's the rules.
 	 */
 	if(realchr == 'g' && !(fl & FmtSharp)) {
 		if(z1+ndigits+z2 >= point) {
 			if(z1+ndigits < point)
 				z2 = point - (z1+ndigits);
 			else{
 				z2 = 0;
 				while(z1+ndigits > point && digits[ndigits-1] == '0')
 					ndigits--;
 			}
 		}
 	}
 
 	/*
 	 * compute width of all digits and decimal point and suffix if any
 	 */
 	wid = z1+ndigits+z2;
 	if(wid > point)
 		wid += dotwid;
 	else if(wid == point){
 		if(fl & FmtSharp)
 			wid += dotwid;
 		else
 			point++;	/* do not print any decimal point */
 	}
 	wid += sufwid;
 
 	/*
 	 * determine sign
 	 */
 	sign = 0;
 	if(neg)
 		sign = '-';
 	else if(fl & FmtSign)
 		sign = '+';
 	else if(fl & FmtSpace)
 		sign = ' ';
 	if(sign)
 		wid++;
 
 	/*
 	 * compute padding
 	 */
 	pad = 0;
 	if((fl & FmtWidth) && fmt->width > wid)
 		pad = fmt->width - wid;
 	if(pad && !(fl & FmtLeft) && (fl & FmtZero)){
 		z1 += pad;
 		point += pad;
 		pad = 0;
 	}
 
 	/*
 	 * format the actual field.  too bad about doing this twice.
 	 */
 	if(fmt->runes){
 		if(pad && !(fl & FmtLeft) && __rfmtpad(fmt, pad) < 0)
 			return -1;
 		rt = (Rune*)fmt->to;
 		rs = (Rune*)fmt->stop;
 		if(sign)
 			FMTRCHAR(fmt, rt, rs, sign);
 		while(z1>0 || ndigits>0 || z2>0) {
 			if(z1 > 0){
 				z1--;
 				c = '0';
 			}else if(ndigits > 0){
 				ndigits--;
 				c = *digits++;
 			}else{
 				z2--;
 				c = '0';
 			}
 			FMTRCHAR(fmt, rt, rs, c);
 			if(--point == 0) {
 				for(p = dot; *p; ){
 					p += chartorune(&r, p);
 					FMTRCHAR(fmt, rt, rs, r);
 				}
 			}
 		}
 		fmt->nfmt += rt - (Rune*)fmt->to;
 		fmt->to = rt;
 		if(sufwid && __fmtcpy(fmt, suf, sufwid, sufwid) < 0)
 			return -1;
 		if(pad && (fl & FmtLeft) && __rfmtpad(fmt, pad) < 0)
 			return -1;
 	}else{
 		if(pad && !(fl & FmtLeft) && __fmtpad(fmt, pad) < 0)
 			return -1;
 		t = (char*)fmt->to;
 		s = (char*)fmt->stop;
 		if(sign)
 			FMTCHAR(fmt, t, s, sign);
 		while(z1>0 || ndigits>0 || z2>0) {
 			if(z1 > 0){
 				z1--;
 				c = '0';
 			}else if(ndigits > 0){
 				ndigits--;
 				c = *digits++;
 			}else{
 				z2--;
 				c = '0';
 			}
 			FMTCHAR(fmt, t, s, c);
 			if(--point == 0)
 				for(p=dot; *p; p++)
 					FMTCHAR(fmt, t, s, *p);
 		}
 		fmt->nfmt += t - (char*)fmt->to;
 		fmt->to = t;
 		if(sufwid && __fmtcpy(fmt, suf, sufwid, sufwid) < 0)
 			return -1;
 		if(pad && (fl & FmtLeft) && __fmtpad(fmt, pad) < 0)
 			return -1;
 	}
 	return 0;
 }