将 N 字节转换为由 Q 编号定义的浮点数

Question

有没有一种简单的方法可以将 N 字节的字节数组转换为由 Q-Number 定义的浮点数。

In 2's Compliance（之前忘了提这个）

示例：0xFFF0 -> 使用 s3.12 Q-Number 的浮点数

https://en.wikipedia.org/wiki/Q_(number_format)

Answer 1

Peter Lawrey 的以下建议：

private static void test(short x) {
    float y = (float)(x & 0x7FFF) / (1 << 12);
    if ((x & 0x8000) != 0)
        y = -y;
    System.out.printf("%04x: %g%n", x, y);
}

测试

test((short)0xFFF0);
test((short)0xFFFF);
test((short)0x0000);
test((short)0x0001);
test((short)0x1000);
test((short)0x9000);
test((short)0x7FFF);

输出

fff0: -7.99609
ffff: -7.99976
0000: 0.00000
0001: 0.000244141
1000: 1.00000
9000: -1.00000
7fff: 7.99976

Answer 2

您可以使用

byte[] bytes = ....
ByteBuffer bb = ByteBuffer.wrap(bytes).order(ByteOrder.????); // check your byte order
while(bb.remaining() > 1) {
    short s = bb.getShort();
    boolean signed = s < 0;
    int value = s & 0x7FFF;
    double d = s / 4096.0;
    if (signed)
        d = -d;
    System.out.println(d);
}

将 N 字节转换为由 Q 编号定义的浮点数

Convert a N-Bytes to a Float defined by the Q-Number

java

arrays

floating-point

bytearray