PTO-ARCH-DATA-TYPES-FORMAT-HIF8

1// PTO-UNIT: {"id":"PTO-ARCH-DATA-TYPES-FORMAT-HIF8","surface":"arch","classification":["data-types","formats","hif8"],"depends_on":["PTO-ARCH-DATA-TYPES-FORMAT-DESCRIPTOR"]}2// DOC-BEGIN: operation3// PTO-REQ-HARDWARE-NUMERIC-001: exact HiF8 dynamic encoding.4
5pure func HiF8NumericFormatDescriptor() => NumericFormatDescriptor6begin7    return NumericFormatDescriptor {8        available = TRUE, kind = NumericFormatKind_HiF8,9        carrier_bits = 8, lane_bits = 8, lanes_per_carrier = 1,10        sign_bits = 1, sign_bit = 7,11        exponent_bits_min = 0, exponent_bits_max = 4,12        fraction_bits_min = 1, fraction_bits_max = 3,13        exponent_bias_available = FALSE, exponent_bias = 0,14        required_low_zero_bits = 0, required_high_zero_bits = 0,15        has_zero = TRUE, has_signed_zero = FALSE, has_subnormal = TRUE,16        has_infinity = TRUE, has_quiet_nan = TRUE,17        has_signaling_nan = FALSE18    };19end;20
21pure func HiF8DecodeDotField(value: bits(8))22    => (HiF8DotField, integer {0..4}, integer {1..3})23begin24    if value[6:3] == '0000' then25        return (HiF8DotField_Denormal, 0, 3);26    elsif value[6:3] == '0001' then27        return (HiF8DotField_D0, 0, 3);28    elsif value[6:4] == '001' then29        return (HiF8DotField_D1, 1, 3);30    elsif value[6:5] == '01' then31        return (HiF8DotField_D2, 2, 3);32    elsif value[6:5] == '10' then33        return (HiF8DotField_D3, 3, 2);34    else return (HiF8DotField_D4, 4, 1);35    end;36end;37
38pure func HiF8FiniteDecomposition(value: bits(8))39    => (boolean, boolean, Word, integer {-1074..1023})40begin41    if value == '10000000' || value == '01101111' ||42       value == '11101111' then43        return (FALSE, FALSE, Zeros{PTO_XLEN}, 0);44    end;45    let (dot, exponent_bits, fraction_bits) = HiF8DecodeDotField(value);46    case dot of47        when HiF8DotField_Denormal =>48            let mantissa = value[2:0];49            if mantissa == Zeros{3} then50                return (TRUE, FALSE, Zeros{PTO_XLEN}, 0);51            else return (TRUE, value[7] == '1', Zeros{PTO_XLEN} + 1,52                         (UInt(mantissa) - 23)53                             as integer {-1074..1023});54            end;55        when HiF8DotField_D0 =>56            return (TRUE, value[7] == '1',57                    LSL(Zeros{PTO_XLEN} + 1, 3) +58                        ZeroExtend{PTO_XLEN}(value[2:0]), -3);59        when HiF8DotField_D1 =>60            var actual_exponent: integer {-15..15} = 1;61            if value[3] == '1' then actual_exponent = -1; end;62            return (TRUE, value[7] == '1',63                    LSL(Zeros{PTO_XLEN} + 1, 3) +64                        ZeroExtend{PTO_XLEN}(value[2:0]),65                    (actual_exponent - 3) as integer {-1074..1023});66        when HiF8DotField_D2 =>67            let magnitude = 2 + UInt(value[3]);68            var actual_exponent: integer {-15..15} = magnitude;69            if value[4] == '1' then actual_exponent = 0 - magnitude; end;70            return (TRUE, value[7] == '1',71                    LSL(Zeros{PTO_XLEN} + 1, 3) +72                        ZeroExtend{PTO_XLEN}(value[2:0]),73                    (actual_exponent - 3) as integer {-1074..1023});74        when HiF8DotField_D3 =>75            let magnitude = 4 + UInt(value[3:2]);76            var actual_exponent: integer {-15..15} = magnitude;77            if value[4] == '1' then actual_exponent = 0 - magnitude; end;78            return (TRUE, value[7] == '1',79                    LSL(Zeros{PTO_XLEN} + 1, 2) +80                        ZeroExtend{PTO_XLEN}(value[1:0]),81                    (actual_exponent - 2) as integer {-1074..1023});82        when HiF8DotField_D4 =>83            let magnitude = 8 + UInt(value[3:1]);84            var actual_exponent: integer {-15..15} = magnitude;85            if value[4] == '1' then actual_exponent = 0 - magnitude; end;86            return (TRUE, value[7] == '1',87                    LSL(Zeros{PTO_XLEN} + 1, 1) +88                        ZeroExtend{PTO_XLEN}(value[0:0]),89                    (actual_exponent - 1) as integer {-1074..1023});90    end;91end;92pure func ClassifyHiF8(value: bits(8)) => NumericValueClass93begin94    if value == '10000000' then return NumericValue_QuietNaN;95    elsif value == '01101111' then return NumericValue_PositiveInfinity;96    elsif value == '11101111' then return NumericValue_NegativeInfinity;97    elsif value == Zeros{8} then return NumericValue_PositiveZero;98    elsif UInt(value[6:0]) <= 7 then99        return NumericValueClassFromFiniteSign(value[7], FALSE, TRUE);100    else return NumericValueClassFromFiniteSign(value[7], FALSE, FALSE);101    end;102end;103
104pure func HiF8CanonicalNaN() => Word105begin106    return Zeros{PTO_XLEN} + 0x80;107end;108// DOC-END: operation109