golang cgo将[]byte形式的缓冲区传递给C函数void*参数的办法

golang通过cgo调用C函数时, 常常会遇到从一个无类型buffer(缓冲区)读取数据进行处理的C函数.
如果用golang 的bufB := make([]byte, BUFFER_SIZE)创建一个缓冲区, 那么可用unsafe.Pointer(&bufB[0])的方式转换后传递给C函数.

示例代码如下:

bufByte := make([]byte, BUFFER_SIZE)
buffer := unsafe.Pointer(&bufB[0])
C.Func(buffer)

实例代码片段如下:

/*
int QISRAudioWrite(const char* sessionID, const void* waveData, unsigned int waveLen,...); //此为C函数声明
*/
	bufB := make([]byte, 3200)
	buffer := unsafe.Pointer(&bufB[0]) //这一行和下面注释掉的3行效果一样
	div := dataSize / 3200
	var i int64
	var audioStatus C.int = C.MSP_AUDIO_SAMPLE_FIRST
	var epStatus C.int = C.MSP_EP_LOOKING_FOR_SPEECH
	var recogStatus C.int = C.MSP_REC_STATUS_INCOMPLETE
	for i = 0; i <= div; i++ {
		n, err := io.ReadFull(f, bufB)
		if err != nil {
			log.Println("QISRAudioWriteAll: Read file end with error: ", err)
			audioStatus = C.MSP_AUDIO_SAMPLE_LAST
		}

		// bufC := C.CString(string(bufB))
		// buffer := unsafe.Pointer(bufC)
		// defer C.free(buffer)
		rc := C.QISRAudioWrite(asr.SessionID, buffer, C.uint(n), audioStatus, &epStatus, &recogStatus)
		if rc != C.MSP_SUCCESS {
			log.Println("QISRAudioWrite error:", rc)
		}
		audioStatus = C.MSP_AUDIO_SAMPLE_CONTINUE
	}