diff options
Diffstat (limited to 'sysdeps/ieee754/ldbl-128ibm/e_ilogbl.c')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/e_ilogbl.c | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/e_ilogbl.c b/sysdeps/ieee754/ldbl-128ibm/e_ilogbl.c index aeace7c977..4088238f30 100644 --- a/sysdeps/ieee754/ldbl-128ibm/e_ilogbl.c +++ b/sysdeps/ieee754/ldbl-128ibm/e_ilogbl.c @@ -31,12 +31,13 @@ static char rcsid[] = "$NetBSD: $"; int __ieee754_ilogbl(long double x) { - int64_t hx; + int64_t hx, hxs; int ix; - double xhi; + double xhi, xlo; - xhi = ldbl_high (x); + ldbl_unpack (x, &xhi, &xlo); EXTRACT_WORDS64 (hx, xhi); + hxs = hx; hx &= 0x7fffffffffffffffLL; if(hx <= 0x0010000000000000LL) { if(hx==0) @@ -45,7 +46,21 @@ int __ieee754_ilogbl(long double x) for (ix = -1022, hx<<=11; hx>0; hx<<=1) ix -=1; return ix; } - else if (hx<0x7ff0000000000000LL) return (hx>>52)-0x3ff; + else if (hx < 0x7ff0000000000000LL) + { + int hexp = (hx >> 52) - 0x3ff; + /* If the high part is a power of 2, and the low part is + nonzero with the opposite sign, the low part affects + the exponent. */ + if ((hx & 0x000fffffffffffffLL) == 0) + { + int64_t lx; + EXTRACT_WORDS64 (lx, xlo); + if ((hxs ^ lx) < 0 && (lx & 0x7fffffffffffffffLL) != 0) + hexp--; + } + return hexp; + } else if (FP_ILOGBNAN != INT_MAX) { /* ISO C99 requires ilogbl(+-Inf) == INT_MAX. */ if (hx==0x7ff0000000000000LL) |