diff options
Diffstat (limited to 'sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c | 75 |
1 files changed, 13 insertions, 62 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c b/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c index 21d1e62dab..8a2d45e2d8 100644 --- a/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c +++ b/sysdeps/ieee754/ldbl-128ibm/mpn2ldbl.c @@ -1,4 +1,4 @@ -/* Copyright (C) 1995, 1996, 1997, 1998, 1999, 2002, 2003, 2004, 2006, 2007 +/* Copyright (C) 1995, 1996, 1997, 1998, 1999, 2002, 2003, 2004, 2006 Free Software Foundation, Inc. This file is part of the GNU C Library. @@ -31,20 +31,19 @@ long double __mpn_construct_long_double (mp_srcptr frac_ptr, int expt, int sign) { union ibm_extended_long_double u; - unsigned long lzcount; + unsigned long hidden2, lzcount; unsigned long long hi, lo; - int exponent2; u.ieee.negative = sign; u.ieee.negative2 = sign; u.ieee.exponent = expt + IBM_EXTENDED_LONG_DOUBLE_BIAS; - u.ieee.exponent2 = 0; - exponent2 = expt - 53 + IBM_EXTENDED_LONG_DOUBLE_BIAS; + u.ieee.exponent2 = expt - 53 + IBM_EXTENDED_LONG_DOUBLE_BIAS; #if BITS_PER_MP_LIMB == 32 /* The low order 53 bits (52 + hidden) go into the lower double */ lo = frac_ptr[0]; lo |= (frac_ptr[1] & ((1LL << (53 - 32)) - 1)) << 32; + hidden2 = (frac_ptr[1] >> (52 - 32)) & ((mp_limb_t) 1); /* The high order 53 bits (52 + hidden) go into the upper double */ hi = (frac_ptr[1] >> (53 - 32)) & ((1 << 11) - 1); hi |= ((unsigned long long) frac_ptr[2]) << 11; @@ -52,6 +51,7 @@ __mpn_construct_long_double (mp_srcptr frac_ptr, int expt, int sign) #elif BITS_PER_MP_LIMB == 64 /* The low order 53 bits (52 + hidden) go into the lower double */ lo = frac_ptr[0] & (((mp_limb_t) 1 << 53) - 1); + hidden2 = (frac_ptr[0] >> 52) & ((mp_limb_t) 1); /* The high order 53 bits (52 + hidden) go into the upper double */ hi = (frac_ptr[0] >> 53) & (((mp_limb_t) 1 << 11) - 1); hi |= (frac_ptr[1] << 11); @@ -59,62 +59,14 @@ __mpn_construct_long_double (mp_srcptr frac_ptr, int expt, int sign) #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for" #endif - if ((hi & (1LL << 52)) == 0 && (hi | lo) != 0) - { - /* denormal number */ - unsigned long long val = hi ? hi : lo; - - if (sizeof (val) == sizeof (long)) - lzcount = __builtin_clzl (val); - else if ((val >> 32) != 0) - lzcount = __builtin_clzl ((long) (val >> 32)); - else - lzcount = __builtin_clzl ((long) val) + 32; - if (hi) - lzcount = lzcount - 11; - else - lzcount = lzcount + 42; - - if (lzcount > u.ieee.exponent) - { - lzcount = u.ieee.exponent; - u.ieee.exponent = 0; - exponent2 -= lzcount; - } - else - { - u.ieee.exponent -= (lzcount - 1); - exponent2 -= (lzcount - 1); - } - - if (lzcount <= 53) - { - hi = (hi << lzcount) | (lo >> (53 - lzcount)); - lo = (lo << lzcount) & ((1LL << 53) - 1); - } - else - { - hi = lo << (lzcount - 53); - lo = 0; - } - } - if (lo != 0L) { /* hidden2 bit of low double controls rounding of the high double. - If hidden2 is '1' and either the explicit mantissa is non-zero - or hi is odd, then round up hi and adjust lo (2nd mantissa) + If hidden2 is '1' then round up hi and adjust lo (2nd mantissa) plus change the sign of the low double to compensate. */ - if ((lo & (1LL << 52)) != 0 - && ((hi & 1) != 0 || (lo & ((1LL << 52) - 1)))) + if (hidden2) { hi++; - if ((hi & ((1LL << 52) - 1)) == 0) - { - if ((hi & (1LL << 53)) != 0) - hi -= 1LL << 52; - u.ieee.exponent++; - } u.ieee.negative2 = !sign; lo = (1LL << 53) - lo; } @@ -133,18 +85,17 @@ __mpn_construct_long_double (mp_srcptr frac_ptr, int expt, int sign) if (lzcount > 0) { lo = lo << lzcount; - exponent2 = exponent2 - lzcount; + u.ieee.exponent2 = u.ieee.exponent2 - lzcount; } - if (exponent2 > 0) - u.ieee.exponent2 = exponent2; - else - lo >>= 1 - exponent2; } else - u.ieee.negative2 = 0; + { + u.ieee.negative2 = 0; + u.ieee.exponent2 = 0; + } u.ieee.mantissa3 = lo & 0xffffffffLL; - u.ieee.mantissa2 = (lo >> 32) & 0xfffff; + u.ieee.mantissa2 = (lo >> 32) & 0xffffff; u.ieee.mantissa1 = hi & 0xffffffffLL; u.ieee.mantissa0 = (hi >> 32) & ((1LL << (LDBL_MANT_DIG - 86)) - 1); |