Fuzion • Idioms • Idiom # 248: Construct a 64-bit floating-point value

Idiom # 248: Construct a 64-bit floating-point value

Code

NYI: this might become a library function in the future, see #3248

d := ((s ? u64.one << 63 : u64.zero) | (e << (f64.significand_bits - 1).as_u64) | m).cast_to_f64

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d := ((s ? u64.one << 63 : u64.zero) | (e << (f64.significand_bits - 1).as_u64) | m).cast_to_f64
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

Running Example

ex248 is

  test_vals := [(false, (u64  0), (u64 1023)),
                (false, (u64  0), (u64 1024)),
                (true , (u64  0), (u64 1023) + 16),
                (true , (u64 66), (u64    7)),
                (true , ((f64 1234).mantissa & f64.mantissa_mask), (f64 1234).exponent_biased.as_u64),
                (false, (u64 1407374883553280),   (u64  1028))]

  for t in test_vals do

    (s,m,e) := t

    d := ((s ? u64.one << 63 : u64.zero) | (e << (f64.significand_bits - 1).as_u64) | m).cast_to_f64

    say "s=$s m=$m e=$e : $d"

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ex248 is
  test_vals := [(false, (u64  0), (u64 1023)),
                (false, (u64  0), (u64 1024)),
                (true , (u64  0), (u64 1023) + 16),
                (true , (u64 66), (u64    7)),
                (true , ((f64 1234).mantissa & f64.mantissa_mask), (f64 1234).exponent_biased.as_u64),
                (false, (u64 1407374883553280),   (u64  1028))]
  for t in test_vals do
    (s,m,e) := t
    d := ((s ? u64.one << 63 : u64.zero) | (e << (f64.significand_bits - 1).as_u64) | m).cast_to_f64
    say "s=$s m=$m e=$e : $d"
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

last changed: 2025-05-13

next: Idiom # 249: Declare and assign multiple variables