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fix various floating point rounding and formatting errors in *printf

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This commit is contained in:
Rich Felker
2011-04-05 09:16:40 -04:00
parent bd1f6eba8c
commit f9569662c0
1 changed files with 25 additions and 17 deletions
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38
src/stdio/vfprintf.c
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@ -193,7 +193,7 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
uint32_t *a, *d, *r, *z; uint32_t *a, *d, *r, *z;
int e2=0, e, i, j, l; int e2=0, e, i, j, l;
char buf[9+LDBL_MANT_DIG/4], *s; char buf[9+LDBL_MANT_DIG/4], *s;
const char *prefix="-+ "; const char *prefix="-0X+0X 0X-0x+0x 0x";
int pl; int pl;
char ebuf0[3*sizeof(int)], *ebuf=&ebuf0[3*sizeof(int)], *estr; char ebuf0[3*sizeof(int)], *ebuf=&ebuf0[3*sizeof(int)], *estr;
@ -201,10 +201,10 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
if (y<0 || 1/y<0) { if (y<0 || 1/y<0) {
y=-y; y=-y;
} else if (fl & MARK_POS) { } else if (fl & MARK_POS) {
prefix++; prefix+=3;
} else if (fl & PAD_POS) { } else if (fl & PAD_POS) {
prefix+=2; prefix+=6;
} else pl=0; } else prefix++, pl=0;
if (!isfinite(y)) { if (!isfinite(y)) {
char *s = (t&32)?"inf":"INF"; char *s = (t&32)?"inf":"INF";
@ -223,15 +223,23 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
long double round = 8.0; long double round = 8.0;
int re; int re;
if (t&32) prefix += 9;
pl += 2;
if (p<0 || p>=LDBL_MANT_DIG/4-1) re=0; if (p<0 || p>=LDBL_MANT_DIG/4-1) re=0;
else re=LDBL_MANT_DIG/4-1-p; else re=LDBL_MANT_DIG/4-1-p;
if (re) { if (re) {
if (pl && *prefix=='-') y=-y;
while (re--) round*=16; while (re--) round*=16;
if (*prefix=='-') {
y=-y;
y-=round;
y+=round;
y=-y;
} else {
y+=round; y+=round;
y-=round; y-=round;
if (y<0) y=-y; }
} }
estr=fmt_u(e2<0 ? -e2 : e2, ebuf); estr=fmt_u(e2<0 ? -e2 : e2, ebuf);
@ -240,17 +248,17 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
*--estr = t+('p'-'a'); *--estr = t+('p'-'a');
s=buf; s=buf;
*s++='0';
*s++=t+('x'-'a');
do { do {
int x=y; int x=y;
*s++=xdigits[x]|(t&32); *s++=xdigits[x]|(t&32);
y=16*(y-x); y=16*(y-x);
if (s-buf==3 && (y||p>0||(fl&ALT_FORM))) *s++='.'; if (s-buf==1 && (y||p>0||(fl&ALT_FORM))) *s++='.';
} while (y); } while (y);
if (p<0) p = s-buf-4; if (p && s-buf-2 < p)
l = 1 + p + (p || (fl&ALT_FORM)) + ebuf-estr; l = (p+2) + (ebuf-estr);
else
l = (s-buf) + (ebuf-estr);
pad(f, ' ', w, pl+l, fl); pad(f, ' ', w, pl+l, fl);
out(f, prefix, pl); out(f, prefix, pl);
@ -258,12 +266,12 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
out(f, buf, s-buf); out(f, buf, s-buf);
pad(f, '0', l-(ebuf-estr)-(s-buf), 0, 0); pad(f, '0', l-(ebuf-estr)-(s-buf), 0, 0);
out(f, estr, ebuf-estr); out(f, estr, ebuf-estr);
pad(f, '0', w, pl+l, fl^LEFT_ADJ); pad(f, ' ', w, pl+l, fl^LEFT_ADJ);
return MAX(w, pl+l); return MAX(w, pl+l);
} }
if (p<0) p=6; if (p<0) p=6;
y *= 0x1p28; e2-=28; if (y) y *= 0x1p28, e2-=28;
if (e2<0) a=r=z=big; if (e2<0) a=r=z=big;
else a=r=z=big+sizeof(big)/sizeof(*big) - LDBL_MANT_DIG - 1; else a=r=z=big+sizeof(big)/sizeof(*big) - LDBL_MANT_DIG - 1;
@ -305,7 +313,7 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
else e=0; else e=0;
/* Perform rounding: j is precision after the radix (possibly neg) */ /* Perform rounding: j is precision after the radix (possibly neg) */
j = p - ((t|32)!='f')*e - ((t|32)=='g'); j = p - ((t|32)!='f')*e - ((t|32)=='g' && p);
if (j < 9*(z-r-1)) { if (j < 9*(z-r-1)) {
uint32_t x; uint32_t x;
/* We avoid C's broken division of negative numbers */ /* We avoid C's broken division of negative numbers */
@ -347,7 +355,7 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
} }
if (!(fl&ALT_FORM)) { if (!(fl&ALT_FORM)) {
/* Count trailing zeros in last place */ /* Count trailing zeros in last place */
if (z>a) for (i=10, j=0; z[-1]%i==0; i*=10, j++); if (z>a && z[-1]) for (i=10, j=0; z[-1]%i==0; i*=10, j++);
else j=9; else j=9;
if ((t|32)=='f') if ((t|32)=='f')
p = MIN(p,MAX(0,9*(z-r-1)-j)); p = MIN(p,MAX(0,9*(z-r-1)-j));