base64ToArrayLE.h

 
const char* base64ToArrayLE = R"JS(/*  src/js/base64ToArrayLE.js  */
function base64ToArrayLE(b64, ArrayCls) {
 
    const bin = atob(b64);
    const bytes = new Uint8Array(bin.length);
    for (let i = 0; i < bin.length; i++){
    bytes[i] = bin.charCodeAt(i);
    }
 
    if (!ArrayCls){
    ArrayCls = Float32Array;
    }
    
    // Intermediate data container. 100% safe endianness 
    const dv = new DataView(bytes.buffer);
 
    // Resulting array (of type Float32Array, for example)
    const n = bytes.byteLength / ArrayCls.BYTES_PER_ELEMENT;
    const out = new ArrayCls(n);
 
    var getFuncName = 'get'+ArrayCls.name.replace('Array','')
    dv.getFunc = dv[getFuncName]
    
    for (let i = 0; i < n; i++){
    out[i] = dv.getFunc(i * ArrayCls.BYTES_PER_ELEMENT, true); // little-endian
    }
 
    return out;
}
 
function demo_base64(){
 
    const elems = document.querySelectorAll("metadata[data-base64]");
    // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
    elems.forEach(elem => {
    // set_image_value_tracker(elem)
    console.info(elem)
    window.metadata = elem
    var b64 = elem.getAttribute("data-base64")
    console.info(b64)
    var type = elem.getAttribute("data-basetype")
    
    switch (type){
    case 'int8':
        type = Int8Array;
        break;
    case 'uint8':
        type = Uint8Array;
        break;
    //case 'Uint8Clamped':
    //   type = Uint8ClampedArray;
    //   break;
    case 'int16':
    case 'short':
        type = Int16Array;
        break;
    case 'uint16':
    case 'unsigned short':
        type = Uint16Array;
        break;
    case 'int32':
        type = Int32Array;
        break;
    case 'uint32':
        type = Uint32Array;
        break;
    /*
    case 'bigInt64':
        type = BigInt64Array;
        break;
    case 'bigUint64':
        type = BigUint64Array;
        break;
    */
    case 'float16':
        type = Float16Array;
        break;
    case 'float': // ?x
    case 'float32':
        type = Float32Array;
        break;
    default:
        console.warn('base64 unsupported type:', type)
        type = null;
    }
    var arr = base64ToArrayLE(b64, type)
    //base64ToFloat32ArrayLE(b64)
    console.info(arr)
    })
}
)JS";