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Ryu_Library/ryu/d2fixed.c  view on Meta::CPAN

  }
  if (precision > 0) {
    result[index++] = '.';
  }
#ifdef RYU_DEBUG
  printf("e2=%d\n", e2);
#endif
  if (e2 < 0) {
    const int32_t idx = -e2 / 16;
#ifdef RYU_DEBUG
    printf("idx=%d\n", idx);
#endif
    const uint32_t blocks = precision / 9 + 1;
    // 0 = don't round up; 1 = round up unconditionally; 2 = round up if odd.
    int roundUp = 0;
    uint32_t i = 0;
    if (blocks <= MIN_BLOCK_2[idx]) {
      i = blocks;
      memset(result + index, '0', precision);
      index += precision;
    } else if (i < MIN_BLOCK_2[idx]) {
      i = MIN_BLOCK_2[idx];
      memset(result + index, '0', 9 * i);
      index += 9 * i;
    }
    for (; i < blocks; ++i) {
      const int32_t j = ADDITIONAL_BITS_2 + (-e2 - 16 * idx);
      const uint32_t p = POW10_OFFSET_2[idx] + i - MIN_BLOCK_2[idx];
      if (p >= POW10_OFFSET_2[idx + 1]) {
        // If the remaining digits are all 0, then we might as well use memset.
        // No rounding required in this case.
        const uint32_t fill = precision - 9 * i;
        memset(result + index, '0', fill);
        index += fill;
        break;
      }
      // Temporary: j is usually around 128, and by shifting a bit, we push it to 128 or above, which is
      // a slightly faster code path in mulShift_mod1e9. Instead, we can just increase the multipliers.
      uint32_t digits = mulShift_mod1e9(m2 << 8, POW10_SPLIT_2[p], j + 8);
#ifdef RYU_DEBUG
      printf("digits=%u\n", digits);
#endif
      if (i < blocks - 1) {
        append_nine_digits(digits, result + index);
        index += 9;
      } else {
        const uint32_t maximum = precision - 9 * i;
        uint32_t lastDigit = 0;
        for (uint32_t k = 0; k < 9 - maximum; ++k) {
          lastDigit = digits % 10;
          digits /= 10;
        }
#ifdef RYU_DEBUG
        printf("lastDigit=%u\n", lastDigit);
#endif
        if (lastDigit != 5) {
          roundUp = lastDigit > 5;
        } else {
          // Is m * 10^(additionalDigits + 1) / 2^(-e2) integer?
          const int32_t requiredTwos = -e2 - (int32_t) precision - 1;
          const bool trailingZeros = requiredTwos <= 0
            || (requiredTwos < 60 && multipleOfPowerOf2(m2, (uint32_t) requiredTwos));
          roundUp = trailingZeros ? 2 : 1;
#ifdef RYU_DEBUG
          printf("requiredTwos=%d\n", requiredTwos);
          printf("trailingZeros=%s\n", trailingZeros ? "true" : "false");
#endif
        }
        if (maximum > 0) {
          append_c_digits(maximum, digits, result + index);
          index += maximum;
        }
        break;
      }
    }
#ifdef RYU_DEBUG
    printf("roundUp=%d\n", roundUp);
#endif
    if (roundUp != 0) {
      int roundIndex = index;
      int dotIndex = 0; // '.' can't be located at index 0
      while (true) {
        --roundIndex;
        char c;
        if (roundIndex == -1 || (c = result[roundIndex], c == '-')) {
          result[roundIndex + 1] = '1';
          if (dotIndex > 0) {
            result[dotIndex] = '0';
            result[dotIndex + 1] = '.';
          }
          result[index++] = '0';
          break;
        }
        if (c == '.') {
          dotIndex = roundIndex;
          continue;
        } else if (c == '9') {
          result[roundIndex] = '0';
          roundUp = 1;
          continue;
        } else {
          if (roundUp == 2 && c % 2 == 0) {
            break;
          }
          result[roundIndex] = c + 1;
          break;
        }
      }
    }
  } else {
    memset(result + index, '0', precision);
    index += precision;
  }
  return index;
}

void d2fixed_buffered(double d, uint32_t precision, char* result) {
  const int len = d2fixed_buffered_n(d, precision, result);
  result[len] = '\0';
}

Ryu_Library/ryu/d2fixed.c  view on Meta::CPAN

      // a slightly faster code path in mulShift_mod1e9. Instead, we can just increase the multipliers.
      digits = (p >= POW10_OFFSET_2[idx + 1]) ? 0 : mulShift_mod1e9(m2 << 8, POW10_SPLIT_2[p], j + 8);
#ifdef RYU_DEBUG
      printf("exact=%" PRIu64 " * (%" PRIu64 " + %" PRIu64 " << 64) >> %d\n", m2, POW10_SPLIT_2[p][0], POW10_SPLIT_2[p][1], j);
      printf("digits=%u\n", digits);
#endif
      if (printedDigits != 0) {
        if (printedDigits + 9 > precision) {
          availableDigits = 9;
          break;
        }
        append_nine_digits(digits, result + index);
        index += 9;
        printedDigits += 9;
      } else if (digits != 0) {
        availableDigits = decimalLength9(digits);
        exp = -(i + 1) * 9 + (int32_t) availableDigits - 1;
        if (availableDigits > precision) {
          break;
        }
        if (printDecimalPoint) {
          append_d_digits(availableDigits, digits, result + index);
          index += availableDigits + 1; // +1 for decimal point
        } else {
          result[index++] = (char) ('0' + digits);
        }
        printedDigits = availableDigits;
        availableDigits = 0;
      }
    }
  }

  const uint32_t maximum = precision - printedDigits;
#ifdef RYU_DEBUG
  printf("availableDigits=%u\n", availableDigits);
  printf("digits=%u\n", digits);
  printf("maximum=%u\n", maximum);
#endif
  if (availableDigits == 0) {
    digits = 0;
  }
  uint32_t lastDigit = 0;
  if (availableDigits > maximum) {
    for (uint32_t k = 0; k < availableDigits - maximum; ++k) {
      lastDigit = digits % 10;
      digits /= 10;
    }
  }
#ifdef RYU_DEBUG
  printf("lastDigit=%u\n", lastDigit);
#endif
  // 0 = don't round up; 1 = round up unconditionally; 2 = round up if odd.
  int roundUp = 0;
  if (lastDigit != 5) {
    roundUp = lastDigit > 5;
  } else {
    // Is m * 2^e2 * 10^(precision + 1 - exp) integer?
    // precision was already increased by 1, so we don't need to write + 1 here.
    const int32_t rexp = (int32_t) precision - exp;
    const int32_t requiredTwos = -e2 - rexp;
    bool trailingZeros = requiredTwos <= 0
      || (requiredTwos < 60 && multipleOfPowerOf2(m2, (uint32_t) requiredTwos));
    if (rexp < 0) {
      const int32_t requiredFives = -rexp;
      trailingZeros = trailingZeros && multipleOfPowerOf5(m2, (uint32_t) requiredFives);
    }
    roundUp = trailingZeros ? 2 : 1;
#ifdef RYU_DEBUG
    printf("requiredTwos=%d\n", requiredTwos);
    printf("trailingZeros=%s\n", trailingZeros ? "true" : "false");
#endif
  }
  if (printedDigits != 0) {
    if (digits == 0) {
      memset(result + index, '0', maximum);
    } else {
      append_c_digits(maximum, digits, result + index);
    }
    index += maximum;
  } else {
    if (printDecimalPoint) {
      append_d_digits(maximum, digits, result + index);
      index += maximum + 1; // +1 for decimal point
    } else {
      result[index++] = (char) ('0' + digits);
    }
  }
#ifdef RYU_DEBUG
  printf("roundUp=%d\n", roundUp);
#endif
  if (roundUp != 0) {
    int roundIndex = index;
    while (true) {
      --roundIndex;
      char c;
      if (roundIndex == -1 || (c = result[roundIndex], c == '-')) {
        result[roundIndex + 1] = '1';
        ++exp;
        break;
      }
      if (c == '.') {
        continue;
      } else if (c == '9') {
        result[roundIndex] = '0';
        roundUp = 1;
        continue;
      } else {
        if (roundUp == 2 && c % 2 == 0) {
          break;
        }
        result[roundIndex] = c + 1;
        break;
      }
    }
  }
  result[index++] = 'e';
  if (exp < 0) {
    result[index++] = '-';
    exp = -exp;
  } else {
    result[index++] = '+';