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Display quiet NaNs as 'NaN'.

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This is recommended by IEEE 754-2008.

We still distinguish signaling NaNs with 'sNaN'.
This commit is contained in:
Jakob Stoklund Olesen
2016-04-05 10:20:32 -07:00
parent 5f706b0a1f
commit 79e765a183
2 changed files with 15 additions and 12 deletions
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7
docs/langref.rst
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@@ -247,6 +247,9 @@ Normal numbers
necessary for :type:`ieee64` which has 52 trailing significand bits necessary for :type:`ieee64` which has 52 trailing significand bits
forming 13 hexadecimal digits with no padding. forming 13 hexadecimal digits with no padding.
Zeros
Positive and negative zero are displayed as ``0.0`` and ``-0.0`` respectively.
Subnormal numbers Subnormal numbers
Compatible with C99: ``-0x0.Tpemin`` where ``T`` are the trailing Compatible with C99: ``-0x0.Tpemin`` where ``T`` are the trailing
significand bits encoded as hexadecimal, and ``emin`` is the minimum exponent significand bits encoded as hexadecimal, and ``emin`` is the minimum exponent
@@ -258,8 +261,8 @@ Infinities
Quiet NaNs Quiet NaNs
Quiet NaNs have the MSB of the trailing significand set. If the remaining Quiet NaNs have the MSB of the trailing significand set. If the remaining
bits of the trailing significand are all zero, the value is displayed as bits of the trailing significand are all zero, the value is displayed as
``-qNaN`` or ``qNaN``. Otherwise, ``-qNaN:0xT`` where ``T`` are the ``-NaN`` or ``NaN``. Otherwise, ``-NaN:0xT`` where ``T`` are the trailing
trailing significand bits encoded as hexadecimal. significand bits encoded as hexadecimal.
Signaling NaNs Signaling NaNs
Displayed as ``-sNaN:0xT``. Displayed as ``-sNaN:0xT``.

20
src/libcretonne/immediates.rs
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@@ -99,9 +99,9 @@ fn format_float(bits: u64, w: u8, t: u8, f: &mut Formatter) -> fmt::Result {
if t_bits & (1 << (t - 1)) != 0 { if t_bits & (1 << (t - 1)) != 0 {
// Quiet NaN. // Quiet NaN.
if payload != 0 { if payload != 0 {
write!(f, "qNaN:0x{:x}", payload) write!(f, "NaN:0x{:x}", payload)
} else { } else {
write!(f, "qNaN") write!(f, "NaN")
} }
} else { } else {
// Signaling NaN. // Signaling NaN.
@@ -186,12 +186,12 @@ mod tests {
"0x0.000002p-126"); "0x0.000002p-126");
assert_eq!(format!("{}", Ieee32::new(f32::INFINITY)), "Inf"); assert_eq!(format!("{}", Ieee32::new(f32::INFINITY)), "Inf");
assert_eq!(format!("{}", Ieee32::new(f32::NEG_INFINITY)), "-Inf"); assert_eq!(format!("{}", Ieee32::new(f32::NEG_INFINITY)), "-Inf");
assert_eq!(format!("{}", Ieee32::new(f32::NAN)), "qNaN"); assert_eq!(format!("{}", Ieee32::new(f32::NAN)), "NaN");
assert_eq!(format!("{}", Ieee32::new(-f32::NAN)), "-qNaN"); assert_eq!(format!("{}", Ieee32::new(-f32::NAN)), "-NaN");
// Construct some qNaNs with payloads. // Construct some qNaNs with payloads.
assert_eq!(format!("{}", Ieee32::new_from_bits(0x7fc00001)), "qNaN:0x1"); assert_eq!(format!("{}", Ieee32::new_from_bits(0x7fc00001)), "NaN:0x1");
assert_eq!(format!("{}", Ieee32::new_from_bits(0x7ff00001)), assert_eq!(format!("{}", Ieee32::new_from_bits(0x7ff00001)),
"qNaN:0x300001"); "NaN:0x300001");
// Signaling NaNs. // Signaling NaNs.
assert_eq!(format!("{}", Ieee32::new_from_bits(0x7f800001)), "sNaN:0x1"); assert_eq!(format!("{}", Ieee32::new_from_bits(0x7f800001)), "sNaN:0x1");
assert_eq!(format!("{}", Ieee32::new_from_bits(0x7fa00001)), assert_eq!(format!("{}", Ieee32::new_from_bits(0x7fa00001)),
@@ -221,13 +221,13 @@ mod tests {
"0x0.0000000000001p-1022"); "0x0.0000000000001p-1022");
assert_eq!(format!("{}", Ieee64::new(f64::INFINITY)), "Inf"); assert_eq!(format!("{}", Ieee64::new(f64::INFINITY)), "Inf");
assert_eq!(format!("{}", Ieee64::new(f64::NEG_INFINITY)), "-Inf"); assert_eq!(format!("{}", Ieee64::new(f64::NEG_INFINITY)), "-Inf");
assert_eq!(format!("{}", Ieee64::new(f64::NAN)), "qNaN"); assert_eq!(format!("{}", Ieee64::new(f64::NAN)), "NaN");
assert_eq!(format!("{}", Ieee64::new(-f64::NAN)), "-qNaN"); assert_eq!(format!("{}", Ieee64::new(-f64::NAN)), "-NaN");
// Construct some qNaNs with payloads. // Construct some qNaNs with payloads.
assert_eq!(format!("{}", Ieee64::new_from_bits(0x7ff8000000000001)), assert_eq!(format!("{}", Ieee64::new_from_bits(0x7ff8000000000001)),
"qNaN:0x1"); "NaN:0x1");
assert_eq!(format!("{}", Ieee64::new_from_bits(0x7ffc000000000001)), assert_eq!(format!("{}", Ieee64::new_from_bits(0x7ffc000000000001)),
"qNaN:0x4000000000001"); "NaN:0x4000000000001");
// Signaling NaNs. // Signaling NaNs.
assert_eq!(format!("{}", Ieee64::new_from_bits(0x7ff0000000000001)), assert_eq!(format!("{}", Ieee64::new_from_bits(0x7ff0000000000001)),
"sNaN:0x1"); "sNaN:0x1");