static double RadixStringToDouble(const char* current,
const char* end,
bool sign,
bool allow_trailing_junk,
double junk_string_value,
const char** trailing_pointer) {
ASSERT(current != end);
// Skip leading 0s.
while (*current == '0') {
++current;
if (current == end) {
*trailing_pointer = end;
return SignedZero(sign);
}
}
int64_t number = 0;
int exponent = 0;
const int radix = (1 << radix_log_2);
do {
int digit;
if (*current >= '0' && *current <= '9' && *current < '0' + radix) {
digit = static_cast<char>(*current) - '0';
} else if (radix > 10 && *current >= 'a' && *current < 'a' + radix - 10) {
digit = static_cast<char>(*current) - 'a' + 10;
} else if (radix > 10 && *current >= 'A' && *current < 'A' + radix - 10) {
digit = static_cast<char>(*current) - 'A' + 10;
} else {
if (allow_trailing_junk || !AdvanceToNonspace(¤t, end)) {
break;
} else {
return junk_string_value;
}
}
number = number * radix + digit;
int overflow = static_cast<int>(number >> 53);
if (overflow != 0) {
// Overflow occurred. Need to determine which direction to round the
// result.
int overflow_bits_count = 1;
while (overflow > 1) {
overflow_bits_count++;
overflow >>= 1;
}
int dropped_bits_mask = ((1 << overflow_bits_count) - 1);
int dropped_bits = static_cast<int>(number) & dropped_bits_mask;
number >>= overflow_bits_count;
exponent = overflow_bits_count;
bool zero_tail = true;
while (true) {
++current;
if (current == end || !isDigit(*current, radix)) break;
zero_tail = zero_tail && *current == '0';
exponent += radix_log_2;
}
if (!allow_trailing_junk && AdvanceToNonspace(¤t, end)) {
return junk_string_value;
}
int middle_value = (1 << (overflow_bits_count - 1));
if (dropped_bits > middle_value) {
number++; // Rounding up.
} else if (dropped_bits == middle_value) {
// Rounding to even to consistency with decimals: half-way case rounds
// up if significant part is odd and down otherwise.
if ((number & 1) != 0 || !zero_tail) {
number++; // Rounding up.
}
}
// Rounding up may cause overflow.
if ((number & ((int64_t)1 << 53)) != 0) {
exponent++;
number >>= 1;
}
break;
}
static double RadixStringToIeee(Iterator* current,
Iterator end,
bool sign,
bool allow_trailing_junk,
double junk_string_value,
bool read_as_double,
bool* result_is_junk) {
ASSERT(*current != end);
const int kDoubleSize = Double::kSignificandSize;
const int kSingleSize = Single::kSignificandSize;
const int kSignificandSize = read_as_double? kDoubleSize: kSingleSize;
*result_is_junk = true;
// Skip leading 0s.
while (**current == '0') {
++(*current);
if (*current == end) {
*result_is_junk = false;
return SignedZero(sign);
}
}
int64_t number = 0;
int exponent = 0;
const int radix = (1 << radix_log_2);
do {
int digit;
if (IsDecimalDigitForRadix(**current, radix)) {
digit = static_cast<char>(**current) - '0';
} else if (IsCharacterDigitForRadix(**current, radix, 'a')) {
digit = static_cast<char>(**current) - 'a' + 10;
} else if (IsCharacterDigitForRadix(**current, radix, 'A')) {
digit = static_cast<char>(**current) - 'A' + 10;
} else {
if (allow_trailing_junk || !AdvanceToNonspace(current, end)) {
break;
} else {
return junk_string_value;
}
}
number = number * radix + digit;
int overflow = static_cast<int>(number >> kSignificandSize);
if (overflow != 0) {
// Overflow occurred. Need to determine which direction to round the
// result.
int overflow_bits_count = 1;
while (overflow > 1) {
overflow_bits_count++;
overflow >>= 1;
}
int dropped_bits_mask = ((1 << overflow_bits_count) - 1);
int dropped_bits = static_cast<int>(number) & dropped_bits_mask;
number >>= overflow_bits_count;
exponent = overflow_bits_count;
bool zero_tail = true;
for (;;) {
++(*current);
if (*current == end || !isDigit(**current, radix)) break;
zero_tail = zero_tail && **current == '0';
exponent += radix_log_2;
}
if (!allow_trailing_junk && AdvanceToNonspace(current, end)) {
return junk_string_value;
}
int middle_value = (1 << (overflow_bits_count - 1));
if (dropped_bits > middle_value) {
number++; // Rounding up.
} else if (dropped_bits == middle_value) {
// Rounding to even to consistency with decimals: half-way case rounds
// up if significant part is odd and down otherwise.
if ((number & 1) != 0 || !zero_tail) {
number++; // Rounding up.
}
}
// Rounding up may cause overflow.
if ((number & ((int64_t)1 << kSignificandSize)) != 0) {
exponent++;
number >>= 1;
}
break;
}