SPI library does not have functions for sending or receiving data blocks

SPI library does not have functions for sending or receiving data blocks.
SPI.transfer has disadvantages.
1. If I need to read from SPI a large block of data I often need to fill an array with a constant, f.e. 0xff
2. If I need to send data block to SPI several times I must fill this array again after each sending because it is filled with data read (that I don't need anyway)

I suggest to add functions like
SPI.send(void* data, size_t len, unsigned char outbyte = 0xff)
and
SPI.receive(void* data, size_t len)

首先检查现有的 SPI.transfer 入口点和 ArduinoCore-API SPI 接口。确定块发送和接收操作应如何处理提议的 data、length 和 0xff 参数，包括在不重新构建缓冲区的情况下重复发送。API 提供这两种操作，并且其行为已覆盖大规模读取和重复写入时，即表示完成。

由索引模型根据 Issue 内容生成。