关于uffs文件系统data_layout 和 ecc_layout疑问?

发布于 2014-04-21 11:20:28 浏览：2142 订阅该版

2 个回答

doushinide 2014-04-22

这家伙很懒，什么也没写！

无意间找到了，贴上来造福后人。
The layout array is unsigned char array, start from offset, followed by size, terminated by [0xFF, 0x00] 。

For example, you have 6 bytes ECC (for page size 512), 8 bytes tag, the status byte is the 5th byte.

To create a spare layout as:
[ D0, D1, D2, D3, S, D4, D5, D6, D7, ECC1, ECC2, ECC3, ECC4, ECC5, ECC6]

D0-D7: 8 bytes tag. 
S: the status byte 
ECC1 - ECC6: 6 bytes ECC.

You should provide layout array as:
Layout array for ecc_layout: [0x09, 0x06, 0xFF, 0x00] 
Layout array for data_layout: [0x00, 0x04, 0x05, 0x04, 0xFF, 0x00] (Note: the 8 bytes tag data is split by status byte at 5th)

在 uffs_setup_storage  函数中有下面一段配置：

```

/* calculate the ecc layout array */
	hw_flash_data_layout[0] = attr->ecc_size + 1; /* ecc size + 1byte block status */
	hw_flash_data_layout[1] = 0x08;
	hw_flash_data_layout[2] = 0xFF;
	hw_flash_data_layout[3] = 0x00;

hw_flash_ecc_layout[0] = 0;
	hw_flash_ecc_layout[1] = attr->ecc_size;
	hw_flash_ecc_layout[2] = 0xFF;
	hw_flash_ecc_layout[3] = 0x00;

```

所以Page size大小改变导致ECC长度变化时，自己无需再做修改。