| // 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 |
| |
| // int64_t __fixunstfdi(long double x); |
| // This file implements the PowerPC 128-bit double-double -> int64_t conversion |
| |
| #include "../int_math.h" |
| #include "DD.h" |
| |
| uint64_t __fixtfdi(long double input) { |
| const DD x = {.ld = input}; |
| const doublebits hibits = {.d = x.s.hi}; |
| |
| const uint32_t absHighWord = |
| (uint32_t)(hibits.x >> 32) & UINT32_C(0x7fffffff); |
| const uint32_t absHighWordMinusOne = absHighWord - UINT32_C(0x3ff00000); |
| |
| // If (1.0 - tiny) <= input < 0x1.0p63: |
| if (UINT32_C(0x03f00000) > absHighWordMinusOne) { |
| // Do an unsigned conversion of the absolute value, then restore the sign. |
| const int unbiasedHeadExponent = absHighWordMinusOne >> 20; |
| |
| int64_t result = hibits.x & INT64_C(0x000fffffffffffff); // mantissa(hi) |
| result |= INT64_C(0x0010000000000000); // matissa(hi) with implicit bit |
| result <<= 10; // mantissa(hi) with one zero preceding bit. |
| |
| const int64_t hiNegationMask = ((int64_t)(hibits.x)) >> 63; |
| |
| // 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| |
| // We need to negate it if head and tail have different signs. |
| const int64_t loNegationMask = ((int64_t)(lobits.x)) >> 63; |
| const int64_t negationMask = loNegationMask ^ hiNegationMask; |
| 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 10 that we shifted the head mantissa by. |
| tailMantissa >>= |
| (unbiasedHeadExponent - (biasedTailExponent - (1023 - 10))); |
| |
| result += tailMantissa; |
| } |
| |
| result >>= (62 - unbiasedHeadExponent); |
| |
| // Restore the sign of the result and return |
| result = (result ^ hiNegationMask) - hiNegationMask; |
| return result; |
| } |
| |
| // Edge cases handled here: |
| |
| // |x| < 1, result is zero. |
| if (1.0 > crt_fabs(x.s.hi)) |
| return INT64_C(0); |
| |
| // x very close to INT64_MIN, care must be taken to see which side we are on. |
| if (x.s.hi == -0x1.0p63) { |
| |
| int64_t result = INT64_MIN; |
| |
| if (0.0 < x.s.lo) { |
| // If the tail is positive, the correct result is something other than |
| // INT64_MIN. we'll need to figure out what it is. |
| |
| const doublebits lobits = {.d = x.s.lo}; |
| int64_t tailMantissa = lobits.x & INT64_C(0x000fffffffffffff); |
| tailMantissa |= INT64_C(0x0010000000000000); |
| |
| // Now we negate the tailMantissa |
| tailMantissa = (tailMantissa ^ INT64_C(-1)) + INT64_C(1); |
| |
| // And shift it by the appropriate amount |
| const int biasedTailExponent = (int)(lobits.x >> 52) & 0x7ff; |
| tailMantissa >>= 1075 - biasedTailExponent; |
| |
| result -= tailMantissa; |
| } |
| |
| return result; |
| } |
| |
| // Signed overflows, infinities, and NaNs |
| if (x.s.hi > 0.0) |
| return INT64_MAX; |
| else |
| return INT64_MIN; |
| } |