Moving get_buffer
parent
decfbd5f81
commit
7e5f11b670
44
float16.cr
44
float16.cr
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@ -50,21 +50,6 @@ def get_buffer(value : UInt16)
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[ ((value >> 8) & 0xFF).to_u8, (value & 0xFF).to_u8 ]
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end
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def get_buffer(value : Float32)
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# TODO: is there a simpler way to perform binary operations over a float?
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# Extract IEEE754 components
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io = IO::Memory.new
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io.write_bytes(value, IO::ByteFormat::NetworkEndian)
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io.rewind
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v = io.gets(4)
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if v.nil?
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raise "cannot perform f32 to f16 on value #{value}"
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end
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v.to_slice
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end
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def get_summary(value : Float32)
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buffer = get_buffer value
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@ -102,6 +87,21 @@ def get_summary(value : UInt16)
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"16-bit: #{str_value} => #{str_sign} #{str_exp} #{str_man}"
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end
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def get_buffer(value : Float32)
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# TODO: is there a simpler way to perform binary operations over a float?
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# Extract IEEE754 components
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io = IO::Memory.new
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io.write_bytes(value, IO::ByteFormat::NetworkEndian)
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io.rewind
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v = io.gets(4)
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if v.nil?
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raise "cannot perform f32 to f16 on value #{value}"
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end
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v.to_slice
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end
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enum ConversionInfo
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OK
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NotANumber
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@ -128,7 +128,6 @@ def f32_to_f16(value : Float32)
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# Set mantissa MSB for NaN (and also keep shifted mantissa bits)
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nan_bit = man == 0 ? 0 : 0x0200
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final_value = (((sign << 15) | 0x7C00 | nan_bit | man) & 0xFFFF).to_u16
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# puts "#{get_summary final_value} => inf or nan"
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conversion_info = if nan_bit != 0
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ConversionInfo::NotANumber
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elsif sign == 0
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@ -144,13 +143,10 @@ def f32_to_f16(value : Float32)
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# Unbias the exponent, then bias for half precision
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half_exp = (exp.to_i64 - 127 + 15).to_i16
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# puts " exp: #{typeof(exp)} -> #{exp}"
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# puts "half_exp: #{typeof(half_exp)} -> #{half_exp}"
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# Check for exponent overflow, return +infinity
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if half_exp >= 0x1F
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final_value = (half_sign | 0x7C00).to_u16
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# puts "#{get_summary final_value} => overflow, return ± inf"
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return final_value, ConversionInfo::Overflow
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end
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@ -159,7 +155,6 @@ def f32_to_f16(value : Float32)
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# Check mantissa for what we can do
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if 14 - half_exp > 24
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# No rounding possibility, so this is a full underflow, return signed zero
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# puts "#{get_summary half_sign.to_u16} => full underflow"
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return half_sign.to_u16, ConversionInfo::FullUnderflow
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end
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@ -167,8 +162,6 @@ def f32_to_f16(value : Float32)
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man = man | 0x0080_0000
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half_man = man >> (14 - half_exp)
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pp! binary_mantisse_f32(man), binary_mantisse_f16(half_man)
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# Check for rounding (see comment above functions)
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round_bit = 1 << (13 - half_exp)
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if (man & round_bit) != 0 && (man & (3 * round_bit - 1)) != 0
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@ -178,26 +171,19 @@ def f32_to_f16(value : Float32)
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# No exponent for subnormals
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final_value = (half_sign | half_man).to_u16
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# puts "#{get_summary final_value} => underflow"
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return final_value, ConversionInfo::Underflow
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end
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# Rebias the exponent
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half_exp = (half_exp) << 10
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half_man = (man >> 13) & 0x03FF
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# puts " man: #{binary_mantisse_f32(man)}"
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# puts "half_man: #{binary_mantisse_f16(half_man)}"
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# Check for rounding (see comment above functions)
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round_bit = 0x0000_1000u32
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final_value = if (man & round_bit) != 0 && (man & (3 * round_bit - 1)) != 0
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# puts "round it"
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# Round it
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((half_sign | half_exp | half_man) + 1).to_u16
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else
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v = (half_sign | half_exp | half_man)
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# puts "NOT round it #{binary_32(v)}"
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# puts "NOT round it #{binary_16(v.to_u16)}"
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(half_sign | half_exp | half_man).to_u16
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end
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