文档OTA流程说的明白, 但是CRC32的计算没有说明
我穷举各种CRC32的算法, 结果都不能和库中crc32函数算出的结果一样,
因为crc32这个函数不可见, 所以不能知道其具体算法.
uint32_t crc32(uint32_t crc, const uint8_t *buf, uint32_t len);

我的OTA操作方式如下:

0. 把编译出的bin文件原封不动直接下载到B区.
   1.下载成功之后, 让单片机自己去计算B区的信息数据, 然后写入B区信息位置(4-8K的位置).
1. 复位单片机,让自带的bootloader将B区固件升级到A区.
   代码如下.

#define A_ZONE_INFO_OFFSET 0
#define B_ZONE_INFO_OFFSET SZ_4KB
#define A_ZONE_IMAGE_OFFSET SZ_8KB
#define B_ZONE_IMAGE_OFFSET SZ_8KB

if (cmd_code == CMD_DOWNLOAD_B_ZONE_IMAGE)
{
uint32_t b_zone_image_base_addr = (pcmd_data[0] << 8 | pcmd_data[1]) * SZ_4KB; //BIN的下载地址
uint32_t image_length = (pcmd_data[2] << 8 | pcmd_data[3]) * SZ_1KB; //BIN的下载长度
uint32_t image_offset = b_zone_image_base_addr + B_ZONE_IMAGE_OFFSET; //bin中程序代码的偏移, bin的前4KB+4KB都是固件信息数据,

	if(Download_data(b_zone_image_base_addr, image_length) != true)
	{
		Printf_info("■->固件下载失败.");
		return;
	}
	//====
	Printf_info("->下载完成.");
	Printf_info("->设置B区固件信息.");

	struct image_info_t info = { 0 };
	flash_read(b_zone_image_base_addr, sizeof(struct jump_table_t), (uint8_t *)&info);
	info.compressed_info.compressed_label = 0xFFFFFFFF;
	info.compressed_info.compressed_image_crc = 0;
	info.crc.image_crc = crc32(0xffffffff, (const uint8_t *)(QSPI0_DAC_ADDRESS + image_offset), image_length);
	info.crc.jump_table_crc = crc32(0xffffffff, (const uint8_t *)(&info), (uint32_t)&(((struct jump_table_t *)0)->checkword));
	info.image_storage_offset = image_offset;
	info.image_length = image_length;
	info.flash_protect_mask = 0x7C;//0xFFFFFFFF;
	info.image_valid = JUMP_TABLE_OTA_IMAGE_VALID;
	//---
	GLOBAL_INT_DISABLE();
	uint16_t status = flash_read_status(false);
	flash_write_status(status & (0xff), false);
	//擦除扇区
	flash_erase(B_ZONE_INFO_OFFSET, SZ_4KB);
	flash_write_status(status, false);
	//写入数据
	flash_write_status(status & (0xff), false);
	flash_write(B_ZONE_INFO_OFFSET, sizeof(struct image_info_t), (uint8_t *)&info);
	//校验写入的数据 
	flash_write_status(status, false);
	GLOBAL_INT_RESTORE();

	uint8_t* Ps = (uint8_t *)&info;
	uint8_t* Pd = (uint8_t*)(QSPI0_DAC_ADDRESS + B_ZONE_INFO_OFFSET);
	for (int i = 0; i < sizeof(struct image_info_t); i++)
	{
		if (*Ps++ != *Pd++)
		{
			Printf_info("■->数据写入错误.");
			Printf_info("->.");
			return;
		}
	}

	Printf_info("->设置B区固件信息完毕.");
	Printf_info("->软复位,进行自动升级.");
	Printf_info("->.");
	Delay_ms(123);
	NVIC_SystemReset();
}