C#相当于从现有数组的.buffer创建的javascript TypedArray？

Question

我正在尝试将javascript函数转换为C#脚本.javascript版本的一个功能是从现有的Float32Array的.buffer创建一个Uint32Array.

有谁知道在C#中这相当于什么？我不是在谈论Float32Array和Uint32Array在C#中的内容我在谈论使用dst变量缓冲区初始化javascript类型数组的方式(参见代码)... https://developer.mozilla.org/en -US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray它很重要,因为其他数组在此函数之后使用(例如)var dstUint32 = new Uint32Array(dst.buffer)进行初始化...

这是代码(src是现有的Float32Array - 请参阅下面的一些初始值)...

compileClassifier = function(src, width, scale, dst) {
        width += 1;
        if (!dst) dst = new Float32Array(src.length);
        var dstUint32 = new Uint32Array(dst.buffer);

        dstUint32[0] = src[0];
        dstUint32[1] = src[1];
        var dstIndex = 1;
        for (var srcIndex = 1, iEnd = src.length - 1; srcIndex < iEnd; ) {
            dst[++dstIndex] = src[++srcIndex];

            var numComplexClassifiers = dstUint32[++dstIndex] = src[++srcIndex];
            for (var j = 0, jEnd = numComplexClassifiers; j < jEnd; ++j) {

                var tilted = dst[++dstIndex] = src[++srcIndex];
                var numFeaturesTimes3 = dstUint32[++dstIndex] = src[++srcIndex] * 3;
                if (tilted) {
                    for (var kEnd = dstIndex + numFeaturesTimes3; dstIndex < kEnd; ) {
                        dstUint32[++dstIndex] = src[++srcIndex] + src[++srcIndex] * width;
                        dstUint32[++dstIndex] = src[++srcIndex] * (width + 1) + ((src[++srcIndex] * (width - 1)) << 16);
                        dst[++dstIndex] = src[++srcIndex];
                    }
                } else {
                    for (var kEnd = dstIndex + numFeaturesTimes3; dstIndex < kEnd; ) {
                        dstUint32[++dstIndex] = src[++srcIndex] + src[++srcIndex] * width;
                        dstUint32[++dstIndex] = src[++srcIndex] + ((src[++srcIndex] * width) << 16);
                        dst[++dstIndex] = src[++srcIndex];
                    }
                }

                var inverseClassifierThreshold = 1 / src[++srcIndex];
                for (var k = 0; k < numFeaturesTimes3; ) {
                    dst[dstIndex - k] *= inverseClassifierThreshold;
                    k += 3;
                }

                if (inverseClassifierThreshold < 0) {
                    dst[dstIndex + 2] = src[++srcIndex];
                    dst[dstIndex + 1] = src[++srcIndex];
                    dstIndex += 2;
                } else {
                    dst[++dstIndex] = src[++srcIndex];
                    dst[++dstIndex] = src[++srcIndex];
                }
            }
        }
        dst = dst.subarray(0, dstIndex + 1);
        return dst;
    }

其中的src变量是由此创建的(这是一个非常简化的版本,完整版本是数千个数字长): -

var classifier = [20,20,0.8226894140243530,3,0,2,3,7,14,4,-1.,3,9,14,2,2.,4.0141958743333817e-003,0.0337941907346249,0.8378106951713562,0,2,1,2,18,4,-1.,7,2,6,4,3.,0.0151513395830989,0.1514132022857666,0.7488812208175659,0,2,1,7,15,9,-1.,1,10,15,3,3.,4.2109931819140911e-003,0.0900492817163467,0.6374819874763489,6.9566087722778320,16,0,2,5,6,2,6,-1.,5,9,2,3,2.,1.6227109590545297e-003,0.0693085864186287];
src = new Float32Array(classifier);

这是在dstUint32和dst的控制台中分别记录的那些数字设置为src(该函数不适用于那些数字,因为我说实际的数组远,更长)它很有趣,几乎没有数字匹配原始数组...

[20, 20, 1062378438, 3, 0, 6, 1641, 61341710, 3279494571, 2109, 30670862, 1140399531, 1024093127, 1062632131, 0, 6, 469, 61341714, 3263430756, 475, 61341702, 1128661142, 1041959952, 1061140142, 0, 6, 1639, 138018831, 3278731586, 2341, 46006287, 1144134386, 1035496386, 1059271173, 1088330890, 16, 0, 6, 1409, 92012546, 3290042412, 2111, 46006274, 1150947372, 1032712617, 4294967295, 4294967295, 0, 4294967295, 4294967295, 4294967295, 0, 4294967295, 4294967295, 4294967295, 0, 4294967295, 4294967295, 4294967295, 0, 4294967295, 4294967295, 4294967295, 0, 4294967295]


[2.802596928649634e-44, 2.802596928649634e-44, 0.822689414024353, 4.203895392974451e-45, 0, 8.407790785948902e-45, 2.2995307799570248e-42, 9.874165102541455e-37, -249.1158905029297, 2.955338461261039e-42, 7.787657921469055e-38, 498.2317810058594, 0.03379419073462486, 0.8378106951713562, 0, 8.407790785948902e-45, 6.572089797683392e-43, 9.874168689865524e-37, -66.00076293945312, 6.656167705542881e-43, 9.874157927893318e-37, 198.00228881835938, 0.1514132022857666, 0.7488812208175659, 0, 8.407790785948902e-45, 2.2967281830283752e-42, 5.597240788537616e-34, -237.47366333007812, 3.280439704984397e-42, 2.7918024463192472e-37, 712.4210205078125, 0.09004928171634674, 0.6374819874763489, 6.956608772277832, 2.2420775429197073e-44, 0, 8.407790785948902e-45, 1.9744295362336673e-42, 1.1848984491218286e-35, -616.252685546875, 2.958141058189689e-42, 2.7917995316184414e-37, 1232.50537109375, 0.06930858641862869, NaN, NaN, 0, NaN, NaN, NaN, 0, NaN, NaN, NaN, 0, NaN, NaN, NaN, 0, NaN, NaN, NaN, 0, NaN]

所以你可以在这里看到代码

dstUint32[0] = src[0];
dstUint32[1] = src[1];

似乎已将BOTH dstUint32 [0]/dstUint32 [1] AND dst [0]/dst [1]设置为某物,只是在dst [0]/dst [1]中该值被记录为2.802596928649634e-44而不是超过20？

Answer 1

• 一个js相当于UInt32Array是UInt32[].
• 一个js相当于Float32Array是float[].
• 的等效ArrayBuffer是byte[].

JavaScript类型数组是数组缓冲区的视图.因此,在UInt32Array的元件不投给浮动,而物理存储的内容-比特-被重新解释为float.

要在C#中执行此操作,您需要执行以下操作之一.

如果你关心共享arraybuffer

如果你关心共享arraybuffer,即你需要在一个数组中进行更改以立即显示在另一个数组中,那么你需要实现整个事情.C#不提供开箱即用的功能.为了实现它,您将需要使用这些InteropServices.Marshal设施.这些将允许您访问底层内存.

如果你不关心共享arraybuffer

如果你只是想在一个方向转换,然后可能稍后再转换回来,但你不需要立即看到更改,或者使用共享的ArrayBuffer,你就会有一个更容易的工作.

• 创建一个MemoryStream,
• 从数组中写入Float32元素
• 阅读UInt32元素

像这样的东西:

    static byte[] ReinterpretAsByteArray(UInt32[] a)
    {
        using (MemoryStream s = new MemoryStream())
        {
            using (BinaryWriter w = new BinaryWriter(s, Encoding.Unicode, true))
            {
                for (int i = 0; i < a.Length; i++)
                {
                    w.Write(a[i]);
                }
            }
            return s.ToArray();
        }
    }
    static float[] ReinterpretAsFloatArray(byte[] b) {
        using (MemoryStream s = new MemoryStream(b, false)) {
            using (BinaryReader r = new BinaryReader(s, Encoding.Unicode, true))
            {
                float[] f = new float[b.Length / 4]; // 4 = sizeof float
                for (int i = 0; i < b.Length; i++)
                {
                    f[i] = r.ReadSingle();
                }
                return f;
            }
        }
    }    

你需要写一个类似的功能字节数组转换成UINT32阵列,并转换一个float数组到一个字节数组,但这种情况正在改变两行的问题.