// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) ???? - INRIA - Scilab
// Copyright (C) ???? - ENPC
// Copyright (C) 2008-2011 - DIGITEO - Allan CORNET
//
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution.  The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2.1-en.txt

// =============================================================================
function [y, Fs, bits] = wavread(wavfile, ext)

    y = [];
    Fs = [];
    bits = [];

    // Read Microsoft .wav sound file.
    // y=wavread(wavfile) reads a .wav file specified by the string wavfile,
    // returning the sampled data in y. The .wav extension is appended
    // if no extension is given.
    // Amplitude values are in the range [-1,+1].
    // [y,fs,bits]=wavread(wavfile) returns the sample rate (fs) in Hertz
    // and the number of bits per sample (bits) used to encode the
    // data in the file.
    // [...]=wavread(wavfile,n) returns only the first n samples from each
    //       channel in the file.
    // [...]=wavread(wavfile,[n1 n2]) returns only samples n1 through n2 from
    //      each channel in the file.
    // siz=wavread(wavfile,"size") returns the size of the audio data contained
    //     in the file in place of the actual audio data, returning the
    //      vector siz=[samples channels].
    // infos=wavread(wavfile,"size") returns a vector with the information about actual
    // audio data.
    // vector infos = [wFormatTag, nChannels, nSamplesPerSec,
    //                 nAvgBytesPerSec, nBlockAlign,
    //                 nBitsPerSample, cbSize, nChannels, samples]


    // Append .wav extension if necessary
    if ( strindex(wavfile, ".") == [] ) then
        wavfile = wavfile + ".wav";
    end

    // Open the file
    [fid, err] = mopen(wavfile, "rb", 1);    // Little-endian
    if (err < 0) then
        error(msprintf(gettext("%s: Cannot open file %s.\n"), "wavread", wavfile));
    end

    // Handle ext optional argument
    if (argn(2) < 2) then
        ext = [];
    end

    if (type(ext) == 10) then
        ext = convstr(ext);
        if (ext <> "size") & (ext <> "info") then
            error(msprintf(gettext("%s: Wrong value for input argument #%d: Must be ""%s"" or ""%s"", an integer or a vector of %d integers.\n"), "wavread", 2, "size", "info", 2));
        end
    elseif (type(ext) == 1) then
        exts = size(ext, "*");
        if (exts > 2) then
            error(msprintf(gettext("%s: Wrong value for input argument: Index range must be specified as a scalar or %d-element vector.\n"), "wavread", 2));
        end
        if (exts == 1) then
            if (ext == 0) then
                ext = "size";  // synonym for size
            else
                ext = [1, ext];
            end
        end
    else
        error(msprintf(gettext("%s: Wrong value for input argument #%d: Must be ""%s"" or ""%s"", an integer or a vector of %d integers.\n"), "wavread", 2, "size", "info", 2));
    end

    Data = [];
    ID = stripblanks(ascii(mget(4, "c", fid)));
    Size = mget(1, "ui", fid);
    if (convstr(ID) ~= "riff") then
        error(msprintf(gettext("%s: An error occurred: %s\n"), "wavread", gettext(".wav file does not contain the RIFF identifier.")));
    end
    rifftype = mget(4, "c", fid);
    dtype = convstr(ascii(rifftype)');
    if (dtype ~= "wave") then
        error(msprintf(gettext("%s: An error occurred: %s\n"), "wavread", gettext(".wav file does not contain the wave identifier.")));
    end

    // Find optional chunks
    found_fmt = 0;
    found_data = 0;
    while ~found_data then
        [ID, Size] = find_cktype(fid);
        select ID
        case "fact" then
            total_bytes = Size;
            orig_pos = mtell(fid);
            nbytes = 4;
            // # of required bytes in <fact-ck> header
            if total_bytes < nbytes then
                error(msprintf(gettext("%s: An error occurred: %s\n"), "wavread", gettext("Error reading .wav file.")));
            end
            factdata = mget(1, "ui", fid); // Samples per second
            rbytes = total_bytes - (mtell(fid) - orig_pos);
            if rbytes then
                mseek(rbytes, fid, "cur");
                if (merror(fid) <> 0) then
                    error(msprintf(gettext("%s: An error occurred: %s\n"), "wavread", gettext("Error reading <fact-ck> chunk.")));
                end
            end

            // bug 4037
        case "bext" then
            error(msprintf(gettext("%s: An error occurred: %s is not supported.\n"), "wavread", "Broadcast Wave Format"));
            return

            // bug 4832 - Sampler Chunk
        case "smpl" then
            error(msprintf(gettext("%s: An error occurred: invalid file format. Error reading <%s> chunk.\n"), "wavread", ID));
            return

        case "fmt" then
            found_fmt = 1;
            [wFormatTag, nChannels, nSamplesPerSec, nAvgBytesPerSec, nBlockAlign, nBitsPerSample, cbSize] = read_wavefmt(fid, Size);

        case "data" then

            found_data = 1;
            if ~found_fmt then
                error(msprintf(gettext("%s: An error occurred: %s\n"), "wavread", gettext("Invalid .wav file: found data before format information.")));
            end
            if (ext == "size") | (ext == "info") | (~(ext == [])) & and(ext == 0) then
                // Caller just wants data size:
                samples = read_wavedat(fid, Size ,wFormatTag, nChannels, nBitsPerSample, -1);
                mclose(fid);
                if (ext == "info") then
                    y = [wFormatTag, nChannels, nSamplesPerSec, nAvgBytesPerSec, nBlockAlign, nBitsPerSample, cbSize, nChannels, samples];
                else // "size"
                    y = [nChannels, samples];
                end
            else
                y = read_wavedat(fid, Size ,wFormatTag, nChannels, nBitsPerSample, ext);
                mclose(fid);
            end

        else
            mseek(Size, fid, "cur")
            if (merror(fid) <> 0) then
                error(msprintf(gettext("%s: An error occurred: %s\n"), "wavread", gettext("Incorrect chunk size information in RIFF file.")))
            end
        end
    end
    Fs = nSamplesPerSec;
    if ( wFormatTag == 1 | wFormatTag == 3) then
        bits = (nBlockAlign / nChannels) * 8;
    else
        // unknown
        bits = [];
    end
endfunction
// =============================================================================
function [ID, Size] = find_cktype(fid)
    ID = stripblanks(ascii(mget(4, "c", fid)));
    Size = mget(1, "ui", fid);
endfunction
// =============================================================================
function [wFormatTag, nChannels, nSamplesPerSec, nAvgBytesPerSec, nBlockAlign, nBitsPerSample, cbSize] = read_wavefmt(fid, total_bytes)
    orig_pos = mtell(fid);
    nbytes = 14; // # of required bytes in  header

    if total_bytes < nbytes then
        error(msprintf(gettext("%s: An error occurred: %s\n"), "read_wavefmt", gettext("Error reading .wav file.")));
    end

    // Read wav data:
    wFormatTag = mget(1, "us", fid);  // Data encoding format
    nChannels = mget(1, "us", fid); // Number of channels
    nSamplesPerSec = mget(1, "ui", fid); // Samples per second
    nAvgBytesPerSec = mget(1, "ui", fid); // Avg transfer rate
    nBlockAlign = mget(1, "us", fid); // Block alignment
    if (and(wFormatTag ~= [1 3])) then
        error(msprintf(gettext("%s: An error occurred: %s\n"), "find_cktype", gettext("Invalid wav format.")));
    else
        [cbSize, nBitsPerSample] = read_fmt_pcm(fid, total_bytes);
    end

    rbytes = total_bytes - (mtell(fid) - orig_pos);
    if rbytes then
        mseek(rbytes, fid, "cur")
        if (merror(fid) <> 0) then
            error(msprintf(gettext("%s: An error occurred: %s\n"), "read_wavefmt", gettext("Error reading .wav file.")));
        end
    end
endfunction
// =============================================================================
function [cbSize, nBitsPerSample] = read_fmt_pcm(fid, total_bytes)
    nbytes = 14;
    cbSize = [];
    nBitsPerSample = [];
    // # of bytes already read
    if (total_bytes < nbytes + 2) then
        error(msprintf(gettext("%s: An error occurred: %s\n"), "find_cktype", gettext("Error reading wav file.")));
    end
    nBitsPerSample = mget(1, "us", fid);
    nbytes = nbytes + 2;
    if (total_bytes > nbytes) then
        if (total_bytes >= nbytes + 2) then
            cbSize = mget(1, "us", fid);
            nbytes = nbytes + 2;
        end
        if (total_bytes > nbytes) then
            mseek(total_bytes - nbytes, fid, "cur")
            if (merror(fid) <> 0) then
                error(msprintf(gettext("%s: An error occurred: %s\n"), "find_cktype", gettext("Error reading wav file.")));
            end
        end
    end
endfunction
// =============================================================================
function Data = read_wavedat(fid, Size, wFormatTag, nChannels, nBitsPerSample, ext)
    fmt_msg = [];
    select wFormatTag
    case 1 then
        // PCM Format:
        Data = read_dat_pcm(fid, Size, nChannels, nBitsPerSample, ext, wFormatTag);
    case 2 then
        fmt_msg = "Microsoft ADPCM";
    case 3 then
        // normalized floating-point
        Data = read_dat_pcm(fid, Size, nChannels, nBitsPerSample, ext, wFormatTag);
    case 6 then
        fmt_msg = "CCITT a-law";
    case 7 then
        fmt_msg = "CCITT mu-law";
    case 17 then
        fmt_msg = "IMA ADPCM";
    case 34 then
        fmt_msg = "DSP Group TrueSpeech TM";
    case 49 then
        fmt_msg = "GSM 6.10";
    case 50 then
        fmt_msg = "MSN Audio";
    case 257 then
        fmt_msg = "IBM Mu-law";
    case 258 then
        fmt_msg = "IBM A-law";
    case 259 then
        fmt_msg = "IBM AVC Adaptive Differential";
    else
        fmt_msg = "Format #" + string(wFormatTag);
    end
    if ~(fmt_msg == []) then
        error(msprintf(gettext("%s: An error occurred: Data compression format %s is not supported.\n"), "read_wavedat", fmt_msg));
    end
endfunction
// =============================================================================
function Data = read_dat_pcm(fid,total_bytes , nChannels, nBitsPerSample, ext, wFormatTag)
    // Determine # bytes/sample - format requires rounding
    //  to next integer number of bytes:
    BytesPerSample = ceil(nBitsPerSample / 8);

    select BytesPerSample
    case 1 then  // unsigned 8-bit
        dtype = "uc";
    case 2 then // signed 16-bit
        dtype = "s";
    case 3 then // signed 24-bit
        dtype = "c";
    case 4 then // signed 32-bit (long)
        if wFormatTag == 3 then
            dtype = "f";
        else
            dtype = "i";
        end
    else
        error(msprintf(gettext("%s: An error occurred: %s\n"), "read_dat_pcm", gettext("Cannot read .wav file  with more than 16 bits per sample.")));
    end//  select BytesPerSample

    // # bytes in this chunk
    total_samples = total_bytes / BytesPerSample;
    SamplesPerChannel = total_samples / nChannels;
    if ((~(ext == [])) & (ext == -1)) then
        // Just return the samples per channel, and seek past data:
        Data = SamplesPerChannel;
        mseek(total_bytes, fid, "cur");
        return
    end
    if (ext == []) then
        ext = [1, SamplesPerChannel];
    else
        if (prod(size(ext)) ~= 2) then
            error(msprintf(gettext("%s: An error occurred: %s\n"), "read_dat_pcm", gettext("Sample limit vector must have 2 entries.")));
            return
        end
        if (ext(1) < 1) | (ext(2) > SamplesPerChannel) then
            error(msprintf(gettext("%s: An error occurred: %s\n"), "read_dat_pcm", gettext("Sample limits out of range.")));
        end
        if (ext(1) > ext(2)) then
            error(msprintf(gettext("%s: An error occurred: %s\n"), "read_dat_pcm", gettext("Invalid sample limits (use ascending order).")));
        end
    end

    if (ext(1) > 1) then
        // Skip if specified:
        mseek(BytesPerSample * (ext(1) - 1) * nChannels, fid, "cur");
    end

    // Read data:
    nSPCext = ext(2) - ext(1) + 1;
    // # samples per channel in extraction range
    extSamples = nChannels * nSPCext;

    //24-bits files need special treatment
    if ( BytesPerSample == 3 ) then
        Data_tmp = [];
        Data_tmp = (mget(3 * nChannels * nSPCext, dtype, fid));
        oct1 = uint8(Data_tmp(1:3:$-1));
        oct2 = uint8(Data_tmp(2:3:$));
        oct3 = Data_tmp(3:3:$);
        Data_tmp2 = (double(oct1) * (2^0) + double(oct2) * (2^8) + double(oct3) * (2^16));
        Data = matrix(Data_tmp2, [nChannels, nSPCext]);
    else
        Data = matrix(mget(nChannels * nSPCext, dtype, fid), [nChannels, nSPCext]);
    end;

    // Skip trailing samples:

    mseek(BytesPerSample * (SamplesPerChannel - ext(2)) * nChannels, fid, "cur");

    // Determine if a pad-byte is appended and skip if present:
    junk = Size;
    if ( junk - fix(junk./2).*2 ) then
        mseek(1, fid, "cur");
    end
    // Normalize data range in [-1 1] (min will hit -1)
    select BytesPerSample
    case 1 then
        Data = (Data - 128) / 128;
    case 2 then
        Data = Data / 32768;
    case 3 then
        Data = Data / (2^23);
    case 4 then
        //  wFormatTag == 3 already normalized
        if wFormatTag <> 3 then
            Data = Data / (2^31);
        end
    end; //normalization in range [-1 +1]
endfunction
// =============================================================================