谁能帮我分析分析这几句，谢谢

囯郭

void SPI_FLASH_StartReadSequence(u32 ReadAddr)
{
  /* Select the FLASH: Chip Select low */
  SPI_FLASH_CS_LOW();
  /* Send "Read from Memory " instruction */
  SPI_FLASH_SendByte(W25X_ReadData);
  /* Send the 24-bit address of the address to read from -----------------------*/
  /* Send ReadAddr high nibble address byte */
  SPI_FLASH_SendByte((ReadAddr & 0xFF0000) >> 16);
  /* Send ReadAddr medium nibble address byte */
  SPI_FLASH_SendByte((ReadAddr& 0xFF00) >> 8);
  /* Send ReadAddr low nibble address byte */
  SPI_FLASH_SendByte(ReadAddr & 0xFF);
}谁能解释下后三句中为什么要现与后在左移16位和8位，这是为什么，实在愚钝我

刀口

顺序写入三个字节,先高后低,u32是4字节组成 的