java.lang.Object
org.apache.arrow.memory.util.Float16
Lifted from Apache Parquet MR project:
https://github.com/apache/parquet-mr/blob/e87b80308869b77f914fcfd04364686e11158950/parquet-column/src/main/java/org/apache/parquet/schema/Float16.java
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Changes made:
- Modify the data type input from Parquet-MR Binary (toFloat(Binary b)) to Arrow Java short (toFloat(short b))
- Expose NAN and POSITIVE_INFINITY variables
- Sign bit: 1 bit
- Exponent width: 5 bits
- Significand: 10 bits
The format is laid out as follows:
1 11111 1111111111 ^ --^-- -----^---- sign | |_______ significand | -- exponentHalf-precision floating points can be useful to save memory and/or bandwidth at the expense of range and precision when compared to single-precision floating points (float32). Ref: https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/FP16.java
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Field Summary
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionstatic int
compare
(short x, short y) Compares the two specified half-precision float values.static boolean
isNaN
(short h) Returns true if the specified half-precision float value represents a Not-a-Number, false otherwise.static float
toFloat
(short b) Converts the specified half-precision float value into a single-precision float value.static short
toFloat16
(float f) Converts the specified single-precision float value into a half-precision float value.static String
toFloatString
(short h) Returns a string representation of the specified half-precision float value.
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Field Details
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POSITIVE_INFINITY
public static final short POSITIVE_INFINITY- See Also:
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NaN
public static final short NaN- See Also:
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Constructor Details
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Float16
public Float16()
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Method Details
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isNaN
public static boolean isNaN(short h) Returns true if the specified half-precision float value represents a Not-a-Number, false otherwise.- Parameters:
h
- A half-precision float value- Returns:
- True if the value is a NaN, false otherwise
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compare
public static int compare(short x, short y) Compares the two specified half-precision float values. The following conditions apply during the comparison:- NaN is considered by this method to be equal to itself and greater than all other
half-precision float values (including
#POSITIVE_INFINITY
) - POSITIVE_ZERO is considered by this method to be greater than NEGATIVE_ZERO.
- Parameters:
x
- The first half-precision float value to compare.y
- The second half-precision float value to compare- Returns:
- The value
0
ifx
is numerically equal toy
, a value less than0
ifx
is numerically less thany
, and a value greater than0
ifx
is numerically greater thany
- NaN is considered by this method to be equal to itself and greater than all other
half-precision float values (including
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toFloat
public static float toFloat(short b) Converts the specified half-precision float value into a single-precision float value. The following special cases are handled: If the input is NaN, the returned value is Float NaN. If the input is POSITIVE_INFINITY or NEGATIVE_INFINITY, the returned value is respectively Float POSITIVE_INFINITY or Float NEGATIVE_INFINITY. If the input is 0 (positive or negative), the returned value is +/-0.0f. Otherwise, the returned value is a normalized single-precision float value.- Parameters:
b
- The half-precision float value to convert to single-precision- Returns:
- A normalized single-precision float value
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toFloat16
public static short toFloat16(float f) Converts the specified single-precision float value into a half-precision float value. The following special cases are handled:If the input is NaN, the returned value is NaN. If the input is Float POSITIVE_INFINITY or Float NEGATIVE_INFINITY, the returned value is respectively POSITIVE_INFINITY or NEGATIVE_INFINITY. If the input is 0 (positive or negative), the returned value is POSITIVE_ZERO or NEGATIVE_ZERO. If the input is a less than MIN_VALUE, the returned value is flushed to POSITIVE_ZERO or NEGATIVE_ZERO. If the input is a less than MIN_NORMAL, the returned value is a denorm half-precision float. Otherwise, the returned value is rounded to the nearest representable half-precision float value.
- Parameters:
f
- The single-precision float value to convert to half-precision- Returns:
- A half-precision float value
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toFloatString
Returns a string representation of the specified half-precision float value. Calling this method is equivalent to callingFloat.toString(toFloat(h))
. SeeFloat.toString(float)
for more information on the format of the string representation.- Parameters:
h
- A half-precision float value in binary little-endian format- Returns:
- A string representation of the specified value
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