diff options
Diffstat (limited to 'lib/builtins/ppc/fixunstfdi.c')
| -rw-r--r-- | lib/builtins/ppc/fixunstfdi.c | 106 |
1 files changed, 52 insertions, 54 deletions
diff --git a/lib/builtins/ppc/fixunstfdi.c b/lib/builtins/ppc/fixunstfdi.c index 5e6e2cedf..8d53f3725 100644 --- a/lib/builtins/ppc/fixunstfdi.c +++ b/lib/builtins/ppc/fixunstfdi.c @@ -1,59 +1,57 @@ -/* This file is distributed under the University of Illinois Open Source - * License. See LICENSE.TXT for details. - */ +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception -/* uint64_t __fixunstfdi(long double x); */ -/* This file implements the PowerPC 128-bit double-double -> uint64_t conversion */ +// uint64_t __fixunstfdi(long double x); +// This file implements the PowerPC 128-bit double-double -> uint64_t conversion #include "DD.h" -uint64_t __fixunstfdi(long double input) -{ - const DD x = { .ld = input }; - const doublebits hibits = { .d = x.s.hi }; - - const uint32_t highWordMinusOne = (uint32_t)(hibits.x >> 32) - UINT32_C(0x3ff00000); - - /* If (1.0 - tiny) <= input < 0x1.0p64: */ - if (UINT32_C(0x04000000) > highWordMinusOne) - { - const int unbiasedHeadExponent = highWordMinusOne >> 20; - - uint64_t result = hibits.x & UINT64_C(0x000fffffffffffff); /* mantissa(hi) */ - result |= UINT64_C(0x0010000000000000); /* matissa(hi) with implicit bit */ - result <<= 11; /* mantissa(hi) left aligned in the int64 field. */ - - /* If the tail is non-zero, we need to patch in the tail bits. */ - if (0.0 != x.s.lo) - { - const doublebits lobits = { .d = x.s.lo }; - int64_t tailMantissa = lobits.x & INT64_C(0x000fffffffffffff); - tailMantissa |= INT64_C(0x0010000000000000); - - /* At this point we have the mantissa of |tail| */ - - const int64_t negationMask = ((int64_t)(lobits.x)) >> 63; - tailMantissa = (tailMantissa ^ negationMask) - negationMask; - - /* Now we have the mantissa of tail as a signed 2s-complement integer */ - - const int biasedTailExponent = (int)(lobits.x >> 52) & 0x7ff; - - /* Shift the tail mantissa into the right position, accounting for the - * bias of 11 that we shifted the head mantissa by. - */ - tailMantissa >>= (unbiasedHeadExponent - (biasedTailExponent - (1023 - 11))); - - result += tailMantissa; - } - - result >>= (63 - unbiasedHeadExponent); - return result; - } - - /* Edge cases are handled here, with saturation. */ - if (1.0 > x.s.hi) - return UINT64_C(0); - else - return UINT64_MAX; +uint64_t __fixunstfdi(long double input) { + const DD x = {.ld = input}; + const doublebits hibits = {.d = x.s.hi}; + + const uint32_t highWordMinusOne = + (uint32_t)(hibits.x >> 32) - UINT32_C(0x3ff00000); + + // If (1.0 - tiny) <= input < 0x1.0p64: + if (UINT32_C(0x04000000) > highWordMinusOne) { + const int unbiasedHeadExponent = highWordMinusOne >> 20; + + uint64_t result = hibits.x & UINT64_C(0x000fffffffffffff); // mantissa(hi) + result |= UINT64_C(0x0010000000000000); // matissa(hi) with implicit bit + result <<= 11; // mantissa(hi) left aligned in the int64 field. + + // If the tail is non-zero, we need to patch in the tail bits. + if (0.0 != x.s.lo) { + const doublebits lobits = {.d = x.s.lo}; + int64_t tailMantissa = lobits.x & INT64_C(0x000fffffffffffff); + tailMantissa |= INT64_C(0x0010000000000000); + + // At this point we have the mantissa of |tail| + + const int64_t negationMask = ((int64_t)(lobits.x)) >> 63; + tailMantissa = (tailMantissa ^ negationMask) - negationMask; + + // Now we have the mantissa of tail as a signed 2s-complement integer + + const int biasedTailExponent = (int)(lobits.x >> 52) & 0x7ff; + + // Shift the tail mantissa into the right position, accounting for the + // bias of 11 that we shifted the head mantissa by. + tailMantissa >>= + (unbiasedHeadExponent - (biasedTailExponent - (1023 - 11))); + + result += tailMantissa; + } + + result >>= (63 - unbiasedHeadExponent); + return result; + } + + // Edge cases are handled here, with saturation. + if (1.0 > x.s.hi) + return UINT64_C(0); + else + return UINT64_MAX; } |