classdef PAMmapper_test < IMDDTestCase
    methods (Test, TestTags = {'unit', 'fast', 'transmit', 'pammapper'})

        
        function roundTripBitMappingForSupportedPamOrders(testCase)
            modulationOrders = [2, 4, 8];

            for M = modulationOrders
                txBits = Informationsignal(allBitPatternsForOrder(M));

                mapper = PAMmapper(M, 0);
                mapped = mapper.map(txBits);
                demapped = mapper.demap(mapped);

                testCase.verifyEqual(double(demapped.signal), double(txBits.signal), ...
                    sprintf("Roundtrip mapping failed for PAM-%d.", M));
            end
        end

        function roundTripPam6ClassicMapping(testCase)
            txBits = Informationsignal(pam6BitStream());

            mapper = PAMmapper(6, 0);
            mapped = mapper.map(txBits);
            demapped = mapper.demap(mapped);

            testCase.verifyEqual(demapped.signal, txBits.signal, ...
                "PAM-6 classic mapping should be lossless for aligned inputs.");
        end

        function roundTripPam6EthMapping(testCase)
            txBits = Informationsignal(pam6BitStream());

            mapper = PAMmapper(6, 0, "eth_style", 1);
            mapped = mapper.map(txBits);
            demapped = mapper.demap(mapped);

            expectedBits = txBits.signal(1:length(demapped.signal));

            testCase.verifyEqual(demapped.signal, expectedBits, ...
                "PAM-6 ETH mapping should be lossless for aligned inputs.");
        end

        function quantizeMapsToNearestConstellationLevel(testCase)
            mapper = PAMmapper(4, 0);
            signalIn = Electricalsignal([-4.0; -0.2; 0.4; 2.9], "fs", 1);

            quantized = mapper.quantize(signalIn);
            expected = [-3; -1; 1; 3] ./ sqrt(5);

            testCase.verifyEqual(quantized.signal, expected, "AbsTol", 1e-12);
        end
    end
end

function bits = allBitPatternsForOrder(M)
    bitWidth = log2(M);
    symbols = (0:M-1).';
    bits = zeros(M, bitWidth);

    for bitIdx = 1:bitWidth
        bits(:, bitIdx) = bitget(symbols, bitWidth - bitIdx + 1);
    end
end

function bits = pam6BitStream()
    combinations = dec2bin(0:31, 5) - '0';
    bits = reshape(combinations.', [], 1);
end