PTO-ARCH-DATA-TYPES-FORMAT-E3M2

1// PTO-UNIT: {"id":"PTO-ARCH-DATA-TYPES-FORMAT-E3M2","surface":"arch","classification":["data-types","formats","e3m2"],"depends_on":["PTO-ARCH-DATA-TYPES-FORMAT-DESCRIPTOR"]}2// DOC-BEGIN: operation3// PTO-REQ-HARDWARE-NUMERIC-001: exact zero-extended E3M2 values.4
5pure func E3M2NumericFormatDescriptor() => NumericFormatDescriptor6begin7    return NumericFormatDescriptor {8        available = TRUE, kind = NumericFormatKind_FixedBinary,9        carrier_bits = 8, lane_bits = 6, lanes_per_carrier = 1,10        sign_bits = 1, sign_bit = 5,11        exponent_bits_min = 3, exponent_bits_max = 3,12        fraction_bits_min = 2, fraction_bits_max = 2,13        exponent_bias_available = TRUE, exponent_bias = 3,14        required_low_zero_bits = 0, required_high_zero_bits = 2,15        has_zero = TRUE, has_signed_zero = TRUE, has_subnormal = TRUE,16        has_infinity = FALSE, has_quiet_nan = FALSE,17        has_signaling_nan = FALSE18    };19end;20
21pure func E3M2FiniteDecomposition(value: bits(8))22    => (boolean, boolean, Word, integer {-1074..1023})23begin24    if value[7:6] != Zeros{2} then25        return (FALSE, FALSE, Zeros{PTO_XLEN}, 0);26    end;27    let exponent = value[4:2];28    let fraction = value[1:0];29    if exponent == Zeros{3} then30        if fraction == Zeros{2} then31            return (TRUE, value[5] == '1', Zeros{PTO_XLEN}, 0);32        else return (TRUE, value[5] == '1',33                     ZeroExtend{PTO_XLEN}(fraction), -4);34        end;35    else return (TRUE, value[5] == '1',36                 LSL(Zeros{PTO_XLEN} + 1, 2) +37                     ZeroExtend{PTO_XLEN}(fraction),38                 (UInt(exponent) - (3 + 2))39                     as integer {-1074..1023});40    end;41end;42
43pure func E3M2EncodingValid(value: bits(8)) => boolean44begin45    return value[7:6] == Zeros{2};46end;47pure func ClassifyE3M2(value: bits(8)) => NumericValueClass48begin49    let exponent = value[4:2];50    let fraction = value[1:0];51    return NumericValueClassFromFiniteSign(value[5],52        exponent == Zeros{3} && fraction == Zeros{2},53        exponent == Zeros{3} && fraction != Zeros{2});54end;55
56pure func E3M2SignedZeroEncodings() => (Word, Word)57begin58    return (Zeros{PTO_XLEN}, Zeros{PTO_XLEN} + 0x20);59end;60// DOC-END: operation61