js-dicom/src/ImageUtility/decoders/decodeBigEndian.js

this is js-dicom

/* eslint no-bitwise: 0 */
function swap16 (val) {
    return ((val & 0xFF) << 8) |
        ((val >> 8) & 0xFF);
}


function decodeBigEndian (imageFrame, pixelData) {
    if (imageFrame.bitsAllocated === 16) {
        let arrayBuffer = pixelData.buffer;
        let offset = pixelData.byteOffset;
        const length = pixelData.length;
        // if pixel data is not aligned on even boundary, shift it so we can create the 16 bit array
        // buffers on it

        if (offset % 2) {
            arrayBuffer = arrayBuffer.slice(offset);
            offset = 0;
        }

        if (imageFrame.pixelRepresentation === 0) {
            imageFrame.pixelData = new Uint16Array(arrayBuffer, offset, length / 2);
        } else {
            imageFrame.pixelData = new Int16Array(arrayBuffer, offset, length / 2);
        }
        // Do the byte swap
        for (let i = 0; i < imageFrame.pixelData.length; i++) {
            imageFrame.pixelData[i] = swap16(imageFrame.pixelData[i]);
        }

    } else if (imageFrame.bitsAllocated === 8) {
        imageFrame.pixelData = pixelData;
    }

    return imageFrame;
}

export default decodeBigEndian;