// 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 #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; }