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LibJS: Add spec comments to Value::to_u8()
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1 changed files with 13 additions and 4 deletions
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@ -1009,15 +1009,24 @@ ThrowCompletionOr<i8> Value::to_i8(VM& vm) const
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// 7.1.11 ToUint8 ( argument ), https://tc39.es/ecma262/#sec-touint8
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ThrowCompletionOr<u8> Value::to_u8(VM& vm) const
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{
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double value = TRY(to_number(vm)).as_double();
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if (!isfinite(value) || value == 0)
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// 1. Let number be ? ToNumber(argument).
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double number = TRY(to_number(vm)).as_double();
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// 2. If number is not finite or number is either +0𝔽 or -0𝔽, return +0𝔽.
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if (!isfinite(number) || number == 0)
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return 0;
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auto int_val = floor(fabs(value));
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if (signbit(value))
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// 3. Let int be the mathematical value whose sign is the sign of number and whose magnitude is floor(abs(ℝ(number))).
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auto int_val = floor(fabs(number));
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if (signbit(number))
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int_val = -int_val;
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// 4. Let int8bit be int modulo 2^8.
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auto int8bit = fmod(int_val, NumericLimits<u8>::max() + 1.0);
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if (int8bit < 0)
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int8bit += NumericLimits<u8>::max() + 1.0;
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// 5. Return 𝔽(int8bit).
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return static_cast<u8>(int8bit);
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}
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