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93 lines
2.5 KiB
93 lines
2.5 KiB
4 years ago
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# BigInt
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A JavaScript BigInt value.
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## Methods
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### New
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```cpp
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static Napi::BigInt Napi::BigInt::New(Napi::Env env, int64_t value);
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```
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- `[in] env`: The environment in which to construct the `Napi::BigInt` object.
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- `[in] value`: The value the JavaScript `BigInt` will contain
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These APIs convert the C `int64_t` and `uint64_t` types to the JavaScript
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`BigInt` type.
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```cpp
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static Napi::BigInt Napi::BigInt::New(Napi::Env env,
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int sign_bit,
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size_t word_count,
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const uint64_t* words);
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```
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- `[in] env`: The environment in which to construct the `Napi::BigInt` object.
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- `[in] sign_bit`: Determines if the resulting `BigInt` will be positive or negative.
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- `[in] word_count`: The length of the words array.
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- `[in] words`: An array of `uint64_t` little-endian 64-bit words.
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This API converts an array of unsigned 64-bit words into a single `BigInt`
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value.
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The resulting `BigInt` is calculated as: (–1)<sup>`sign_bit`</sup> (`words[0]`
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× (2<sup>64</sup>)<sup>0</sup> + `words[1]` × (2<sup>64</sup>)<sup>1</sup> + …)
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Returns a new JavaScript `BigInt`.
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### Constructor
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```cpp
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Napi::BigInt();
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```
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Returns a new empty JavaScript `Napi::BigInt`.
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### Int64Value
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```cpp
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int64_t Napi::BitInt::Int64Value(bool* lossless) const;
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```
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- `[out] lossless`: Indicates whether the `BigInt` value was converted losslessly.
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Returns the C `int64_t` primitive equivalent of the given JavaScript
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`BigInt`. If needed it will truncate the value, setting lossless to false.
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### Uint64Value
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```cpp
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uint64_t Napi::BigInt::Uint64Value(bool* lossless) const;
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```
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- `[out] lossless`: Indicates whether the `BigInt` value was converted
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losslessly.
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Returns the C `uint64_t` primitive equivalent of the given JavaScript
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`BigInt`. If needed it will truncate the value, setting lossless to false.
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### WordCount
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```cpp
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size_t Napi::BigInt::WordCount() const;
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```
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Returns the number of words needed to store this `BigInt` value.
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### ToWords
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```cpp
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void Napi::BigInt::ToWords(size_t* word_count, int* sign_bit, uint64_t* words);
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```
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- `[out] sign_bit`: Integer representing if the JavaScript `BigInt` is positive
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or negative.
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- `[in/out] word_count`: Must be initialized to the length of the words array.
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Upon return, it will be set to the actual number of words that would be
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needed to store this `BigInt`.
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- `[out] words`: Pointer to a pre-allocated 64-bit word array.
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Returns a single `BigInt` value into a sign bit, 64-bit little-endian array,
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and the number of elements in the array.
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