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Ryu_Library/ryu/f2s.c  view on Meta::CPAN

    } else if (q < 31) { // TODO(ulfjack): Use a tighter bound here.
      vrIsTrailingZeros = multipleOfPowerOf2_32(mv, q - 1);
#ifdef RYU_DEBUG
      printf("vr is trailing zeros=%s\n", vrIsTrailingZeros ? "true" : "false");
#endif
    }
  }
#ifdef RYU_DEBUG
  printf("e10=%d\n", e10);
  printf("V+=%u\nV =%u\nV-=%u\n", vp, vr, vm);
  printf("vm is trailing zeros=%s\n", vmIsTrailingZeros ? "true" : "false");
  printf("vr is trailing zeros=%s\n", vrIsTrailingZeros ? "true" : "false");
#endif

  // Step 4: Find the shortest decimal representation in the interval of valid representations.
  int32_t removed = 0;
  uint32_t output;
  if (vmIsTrailingZeros || vrIsTrailingZeros) {
    // General case, which happens rarely (~4.0%).
    while (vp / 10 > vm / 10) {
#ifdef __clang__ // https://bugs.llvm.org/show_bug.cgi?id=23106
      // The compiler does not realize that vm % 10 can be computed from vm / 10
      // as vm - (vm / 10) * 10.
      vmIsTrailingZeros &= vm - (vm / 10) * 10 == 0;
#else
      vmIsTrailingZeros &= vm % 10 == 0;
#endif
      vrIsTrailingZeros &= lastRemovedDigit == 0;
      lastRemovedDigit = (uint8_t) (vr % 10);
      vr /= 10;
      vp /= 10;
      vm /= 10;
      ++removed;
    }
#ifdef RYU_DEBUG
    printf("V+=%u\nV =%u\nV-=%u\n", vp, vr, vm);
    printf("d-10=%s\n", vmIsTrailingZeros ? "true" : "false");
#endif
    if (vmIsTrailingZeros) {
      while (vm % 10 == 0) {
        vrIsTrailingZeros &= lastRemovedDigit == 0;
        lastRemovedDigit = (uint8_t) (vr % 10);
        vr /= 10;
        vp /= 10;
        vm /= 10;
        ++removed;
      }
    }
#ifdef RYU_DEBUG
    printf("%u %d\n", vr, lastRemovedDigit);
    printf("vr is trailing zeros=%s\n", vrIsTrailingZeros ? "true" : "false");
#endif
    if (vrIsTrailingZeros && lastRemovedDigit == 5 && vr % 2 == 0) {
      // Round even if the exact number is .....50..0.
      lastRemovedDigit = 4;
    }
    // We need to take vr + 1 if vr is outside bounds or we need to round up.
    output = vr + ((vr == vm && (!acceptBounds || !vmIsTrailingZeros)) || lastRemovedDigit >= 5);
  } else {
    // Specialized for the common case (~96.0%). Percentages below are relative to this.
    // Loop iterations below (approximately):
    // 0: 13.6%, 1: 70.7%, 2: 14.1%, 3: 1.39%, 4: 0.14%, 5+: 0.01%
    while (vp / 10 > vm / 10) {
      lastRemovedDigit = (uint8_t) (vr % 10);
      vr /= 10;
      vp /= 10;
      vm /= 10;
      ++removed;
    }
#ifdef RYU_DEBUG
    printf("%u %d\n", vr, lastRemovedDigit);
    printf("vr is trailing zeros=%s\n", vrIsTrailingZeros ? "true" : "false");
#endif
    // We need to take vr + 1 if vr is outside bounds or we need to round up.
    output = vr + (vr == vm || lastRemovedDigit >= 5);
  }
  const int32_t exp = e10 + removed;

#ifdef RYU_DEBUG
  printf("V+=%u\nV =%u\nV-=%u\n", vp, vr, vm);
  printf("O=%u\n", output);
  printf("EXP=%d\n", exp);
#endif

  floating_decimal_32 fd;
  fd.exponent = exp;
  fd.mantissa = output;
  return fd;
}

static inline int to_chars(const floating_decimal_32 v, const bool sign, char* const result) {
  // Step 5: Print the decimal representation.
  int index = 0;
  if (sign) {
    result[index++] = '-';
  }

  uint32_t output = v.mantissa;
  const uint32_t olength = decimalLength9(output);

#ifdef RYU_DEBUG
  printf("DIGITS=%u\n", v.mantissa);
  printf("OLEN=%u\n", olength);
  printf("EXP=%u\n", v.exponent + olength);
#endif

  // Print the decimal digits.
  // The following code is equivalent to:
  // for (uint32_t i = 0; i < olength - 1; ++i) {
  //   const uint32_t c = output % 10; output /= 10;
  //   result[index + olength - i] = (char) ('0' + c);
  // }
  // result[index] = '0' + output % 10;
  uint32_t i = 0;
  while (output >= 10000) {
#ifdef __clang__ // https://bugs.llvm.org/show_bug.cgi?id=38217
    const uint32_t c = output - 10000 * (output / 10000);
#else
    const uint32_t c = output % 10000;
#endif
    output /= 10000;