Add a bigint stub and reenable grisu

This commit is contained in:
Victor Zverovich 2019-09-07 12:54:16 -07:00
parent b2f0b6e44e
commit 56b5c192a0
3 changed files with 57 additions and 3 deletions

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@ -466,6 +466,24 @@ FMT_FUNC fp get_cached_power(int min_exponent, int& pow10_exponent) {
return fp(data::pow10_significands[index], data::pow10_exponents[index]);
}
class bigint {
private:
basic_memory_buffer<uint32_t> value_;
static FMT_CONSTEXPR_DECL const int radix = 32;
friend struct formatter<bigint>;
public:
explicit bigint(uint64_t n) {
value_.resize(2);
value_[0] = n & ~uint32_t(0);
value_[1] = static_cast<uint32_t>(n >> 32);
}
bigint(const bigint&) = delete;
void operator=(const bigint&) = delete;
};
enum round_direction { unknown, up, down };
// Given the divisor (normally a power of 10), the remainder = v % divisor for
@ -710,7 +728,7 @@ FMT_API bool grisu_format(Double value, buffer<char>& buf, int precision,
if (precision != -1) {
if (precision > 17) return false;
fp_value.normalize();
auto cached_pow = get_cached_power(
const auto cached_pow = get_cached_power(
min_exp - (fp_value.e + fp::significand_size), cached_exp10);
fp_value = fp_value * cached_pow;
fixed_handler handler{buf.data(), 0, precision, -cached_exp10, fixed};
@ -738,14 +756,18 @@ FMT_API bool grisu_format(Double value, buffer<char>& buf, int precision,
grisu_shortest_handler<3> handler{buf.data(), 0, (upper - fp_value).f};
result = grisu_gen_digits(upper, upper.f - lower.f, exp, handler);
size = handler.size;
if (result == digits::error) {
// TODO: use fallback
return false;
}
} else {
++lower.f; // \tilde{M}^- + 1 ulp -> M^-_{\uparrow}.
--upper.f; // \tilde{M}^+ - 1 ulp -> M^+_{\downarrow}.
grisu_shortest_handler<2> handler{buf.data(), 0, (upper - fp_value).f};
result = grisu_gen_digits(upper, upper.f - lower.f, exp, handler);
size = handler.size;
assert(result != digits::error);
}
if (result == digits::error) return false;
buf.resize(to_unsigned(size));
}
exp -= cached_exp10;
@ -831,6 +853,29 @@ char* sprintf_format(Double value, internal::buffer<char>& buf,
}
} // namespace internal
template <> struct formatter<internal::bigint> {
format_parse_context::iterator parse(format_parse_context& ctx) {
return ctx.begin();
}
format_context::iterator format(const internal::bigint& n,
format_context& ctx) {
auto out = ctx.out();
bool first = true;
for (auto i = n.value_.size(); i > 0; --i) {
auto value = n.value_[i - 1];
if (first) {
if (value == 0 && i > 1) continue;
out = format_to(out, "{:x}", value);
first = false;
continue;
}
out = format_to(out, "{:08x}", value);
}
return out;
}
};
#if FMT_USE_WINDOWS_H
FMT_FUNC internal::utf8_to_utf16::utf8_to_utf16(string_view s) {

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@ -445,7 +445,7 @@ OutputIt copy_str(InputIt begin, InputIt end, OutputIt it) {
}
#ifndef FMT_USE_GRISU
# define FMT_USE_GRISU 0
# define FMT_USE_GRISU 1
#endif
template <typename T> constexpr bool use_grisu() {

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@ -22,8 +22,17 @@
#undef max
using fmt::internal::bigint;
using fmt::internal::fp;
static_assert(!std::is_copy_constructible<bigint>::value, "");
static_assert(!std::is_copy_assignable<bigint>::value, "");
TEST(BigIntTest, Construct) {
EXPECT_EQ("42", fmt::format("{}", bigint(0x42)));
EXPECT_EQ("123456789abcedf0", fmt::format("{}", bigint(0x123456789abcedf0)));
}
template <bool is_iec559> void test_construct_from_double() {
fmt::print("warning: double is not IEC559, skipping FP tests\n");
}