PTO-ARCH-DATA-TYPES-FORMAT-FP16

1// PTO-UNIT: {"id":"PTO-ARCH-DATA-TYPES-FORMAT-FP16","surface":"arch","classification":["data-types","formats","fp16"],"depends_on":["PTO-ARCH-DATA-TYPES-FORMAT-DESCRIPTOR"]}2// DOC-BEGIN: operation3// PTO-REQ-HARDWARE-NUMERIC-001: exact FP16 encoding and finite values.4
5pure func FP16NumericFormatDescriptor() => NumericFormatDescriptor6begin7    return NumericFormatDescriptor {8        available = TRUE, kind = NumericFormatKind_FixedBinary,9        carrier_bits = 16, lane_bits = 16, lanes_per_carrier = 1,10        sign_bits = 1, sign_bit = 15,11        exponent_bits_min = 5, exponent_bits_max = 5,12        fraction_bits_min = 10, fraction_bits_max = 10,13        exponent_bias_available = TRUE, exponent_bias = 15,14        required_low_zero_bits = 0, required_high_zero_bits = 0,15        has_zero = TRUE, has_signed_zero = TRUE, has_subnormal = TRUE,16        has_infinity = TRUE, has_quiet_nan = TRUE,17        has_signaling_nan = TRUE18    };19end;20
21pure func FP16FiniteDecomposition(value: bits(16))22    => (boolean, boolean, Word, integer {-1074..1023})23begin24    let exponent = value[14:10];25    let fraction = value[9:0];26    if exponent == Ones{5} then27        return (FALSE, FALSE, Zeros{PTO_XLEN}, 0);28    elsif exponent == Zeros{5} then29        if fraction == Zeros{10} then30            return (TRUE, value[15] == '1', Zeros{PTO_XLEN}, 0);31        else return (TRUE, value[15] == '1',32                     ZeroExtend{PTO_XLEN}(fraction), -24);33        end;34    else return (TRUE, value[15] == '1',35                 LSL(Zeros{PTO_XLEN} + 1, 10) +36                     ZeroExtend{PTO_XLEN}(fraction),37                 (UInt(exponent) - (15 + 10))38                     as integer {-1074..1023});39    end;40end;41pure func ClassifyFP16(value: bits(16)) => NumericValueClass42begin43    let exponent = value[14:10];44    let fraction = value[9:0];45    if exponent == Ones{5} then46        if fraction == Zeros{10} then47            if value[15] == '1' then return NumericValue_NegativeInfinity;48            else return NumericValue_PositiveInfinity;49            end;50        elsif fraction[9] == '1' then return NumericValue_QuietNaN;51        else return NumericValue_SignalingNaN;52        end;53    end;54    return NumericValueClassFromFiniteSign(value[15],55        exponent == Zeros{5} && fraction == Zeros{10},56        exponent == Zeros{5} && fraction != Zeros{10});57end;58
59pure func FP16CanonicalNaN() => Word60begin61    return Zeros{PTO_XLEN} + 0x7e00;62end;63
64pure func FP16SignedZeroEncodings() => (Word, Word)65begin66    return (Zeros{PTO_XLEN}, Zeros{PTO_XLEN} + 0x8000);67end;68// DOC-END: operation69