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| author | Rich Felker <dalias@aerifal.cx> | 2012-04-21 14:14:10 -0400 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2012-04-21 14:14:10 -0400 |
| commit | 77731d0ec16027cb0e3a593d5dd9bb906932303e (patch) | |
| tree | dca09393c7db4376d8f6a470dbbf0e857060adfa /src/internal | |
| parent | 2df2a97a20df22f598810b88409eb6107d23e7e1 (diff) | |
| download | musl-77731d0ec16027cb0e3a593d5dd9bb906932303e.tar.gz musl-77731d0ec16027cb0e3a593d5dd9bb906932303e.tar.xz musl-77731d0ec16027cb0e3a593d5dd9bb906932303e.zip | |
make floatscan correctly set errno for overflow/underflow
care is taken that the setting of errno correctly reflects underflow condition. scanning exact denormal values does not result in ERANGE, nor does scanning values (such as the usual string definition of FLT_MIN) which are actually less than the smallest normal number but which round to a normal result. only the decimal case is handled so far; hex float require a separate fix to come later.
Diffstat (limited to 'src/internal')
| -rw-r--r-- | src/internal/floatscan.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/src/internal/floatscan.c b/src/internal/floatscan.c index dbe07987..aa962f41 100644 --- a/src/internal/floatscan.c +++ b/src/internal/floatscan.c @@ -24,6 +24,8 @@ #define MASK (KMAX-1) +#define CONCAT2(x,y) x ## y +#define CONCAT(x,y) CONCAT2(x,y) static long long scanexp(FILE *f, int pok) { @@ -63,6 +65,8 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po int gotdig = 0, gotrad = 0; int rp; int e2; + int emax = -emin-bits+3; + int denormal = 0; long double y; long double frac=0; long double bias=0; @@ -250,6 +254,7 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po if (bits > LDBL_MANT_DIG+e2-emin) { bits = LDBL_MANT_DIG+e2-emin; if (bits<0) bits=0; + denormal = 1; } /* Calculate bias term to force rounding, move out lower bits */ @@ -280,11 +285,18 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po y += frac; y -= bias; - y = scalbnl(y, e2); - - if (!y) errno = ERANGE; + if ((e2+LDBL_MANT_DIG & INT_MAX) > emax-5) { + if (fabs(y) >= CONCAT(0x1p, LDBL_MANT_DIG)) { + if (denormal && bits==LDBL_MANT_DIG+e2-emin) + denormal = 0; + y *= 0.5; + e2++; + } + if (e2+LDBL_MANT_DIG>emax || (denormal && frac)) + errno = ERANGE; + } - return y; + return scalbnl(y, e2); } static long double hexfloat(FILE *f, int bits, int emin, int sign, int pok) |