icuSources/i18n/double-conversion-diy-fp.cpp

   1 // © 2018 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html
   3 //
   4 // From the double-conversion library. Original license:
   5 //
   6 // Copyright 2010 the V8 project authors. All rights reserved.
   7 // Redistribution and use in source and binary forms, with or without
   8 // modification, are permitted provided that the following conditions are
   9 // met:
  10 //
  11 //     * Redistributions of source code must retain the above copyright
  12 //       notice, this list of conditions and the following disclaimer.
  13 //     * Redistributions in binary form must reproduce the above
  14 //       copyright notice, this list of conditions and the following
  15 //       disclaimer in the documentation and/or other materials provided
  16 //       with the distribution.
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  20 //
  21 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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  31 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32
  33 // ICU PATCH: ifdef around UCONFIG_NO_FORMATTING
  34 #include "unicode/utypes.h"
  35 #if !UCONFIG_NO_FORMATTING
  36
  37 // ICU PATCH: Customize header file paths for ICU.
  38
  39 #include "double-conversion-diy-fp.h"
  40 #include "double-conversion-utils.h"
  41
  42 // ICU PATCH: Wrap in ICU namespace
  43 U_NAMESPACE_BEGIN
  44
  45 namespace double_conversion {
  46
  47 void DiyFp::Multiply(const DiyFp& other) {
  48   // Simply "emulates" a 128 bit multiplication.
  49   // However: the resulting number only contains 64 bits. The least
  50   // significant 64 bits are only used for rounding the most significant 64
  51   // bits.
  52   const uint64_t kM32 = 0xFFFFFFFFU;
  53   uint64_t a = f_ >> 32;
  54   uint64_t b = f_ & kM32;
  55   uint64_t c = other.f_ >> 32;
  56   uint64_t d = other.f_ & kM32;
  57   uint64_t ac = a * c;
  58   uint64_t bc = b * c;
  59   uint64_t ad = a * d;
  60   uint64_t bd = b * d;
  61   uint64_t tmp = (bd >> 32) + (ad & kM32) + (bc & kM32);
  62   // By adding 1U << 31 to tmp we round the final result.
  63   // Halfway cases will be round up.
  64   tmp += 1U << 31;
  65   uint64_t result_f = ac + (ad >> 32) + (bc >> 32) + (tmp >> 32);
  66   e_ += other.e_ + 64;
  67   f_ = result_f;
  68 }
  69
  70 }  // namespace double_conversion
  71
  72 // ICU PATCH: Close ICU namespace
  73 U_NAMESPACE_END
  74 #endif // ICU PATCH: close #if !UCONFIG_NO_FORMATTING