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[inc/fdb_low_lvl] fix An error occurred in FDB_ALIGN(size, align) whe…
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…n align is not 2 to the nth power (#233)
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@DarryZh
DarryZh authored Aug 17, 2023
1 parent fab8a16 commit 3e441f6
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2 changes: 1 addition & 1 deletion inc/fdb_low_lvl.h
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Expand Up @@ -29,7 +29,7 @@
/* Return the most contiguous size aligned at specified width. RT_ALIGN(13, 4)
* would return 16.
*/
#define FDB_ALIGN(size, align) (((size) + (align) - 1) & ~((align) - 1))
#define FDB_ALIGN(size, align) ((size + align - 1) - ((size + align -1) % align))
/* align by write granularity */
#define FDB_WG_ALIGN(size) (FDB_ALIGN(size, (FDB_WRITE_GRAN + 7)/8))
/**
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7 comments on commit 3e441f6

@hsSam
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@hsSam hsSam commented on 3e441f6 Sep 18, 2023

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这个更新后我原来正常使用的程序初始化后，读取数据报错了。

�[32;22m[I/FAL] Flash Abstraction Layer (V0.5.99) initialize success.�[0m
[FlashDB] FlashDB V2.0.0 is initialize success.
[FlashDB] You can get the latest version on https://github.com/armink/FlashDB .
fdb_kvdb_init: 0
[FlashDB][kv][env][kvdb] Error: The KV (@0x00000014) CRC32 check failed!

@guoweilkd
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This commit cause macro expansion errors, stm32f405 demo will be stuck in CRC32 check. I use the following code to workground

#define FDB_ALIGN(size, align)                    ((size + align - 1) - ((size + align -1) % align))
/* align by write granularity */
#define FDB_WG_ALIGN(size)                        (FDB_ALIGN(size, ((FDB_WRITE_GRAN + 7)/8)))

@armink
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@armink armink commented on 3e441f6 Oct 11, 2023

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@hsSam @guoweilkd 你们的 FDB_WRITE_GRAN 都是配置的多大的呀？

@guoweilkd
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我用的就是stm32f405的demo, FDB_WRITE_GRAN = 8, 直接跑demo会陷入到crc死循环中,具体代码在create_kv_blob()函数中的如下位置:

static fdb_err_t create_kv_blob(fdb_kvdb_t db, kv_sec_info_t sector, const char *key, const void *value, size_t len)
{
    ...
    kv_hdr.crc32 = fdb_calc_crc32(kv_hdr.crc32, &kv_hdr.name_len, sizeof(uint32_t));
    kv_hdr.crc32 = fdb_calc_crc32(kv_hdr.crc32, &kv_hdr.value_len, sizeof(uint32_t));
    kv_hdr.crc32 = fdb_calc_crc32(kv_hdr.crc32, key, kv_hdr.name_len);
    align_remain = FDB_WG_ALIGN(kv_hdr.name_len) - kv_hdr.name_len; // name_len = 10时, 宏展开变成了9, 9 - 10 成了一个负数,造成如下死循环
    while (align_remain--) {
        kv_hdr.crc32 = fdb_calc_crc32(kv_hdr.crc32, &ff, 1);
    }
    kv_hdr.crc32 = fdb_calc_crc32(kv_hdr.crc32, value, kv_hdr.value_len);
    align_remain = FDB_WG_ALIGN(kv_hdr.value_len) - kv_hdr.value_len;
    while (align_remain--) {
        kv_hdr.crc32 = fdb_calc_crc32(kv_hdr.crc32, &ff, 1);
    }
    ....
}

@armink
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@armink armink commented on 3e441f6 Oct 12, 2023

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@guoweilkd FDB_WG_ALIGN(10) 在 FDB_WRITE_GRAN = 8 时，结果应该是 10 吧

FDB_WG_ALIGN(10) = FDB_ALIGN(10, 1) = (10 + 1 - 1) - ((10 + 1 - 1) % 1) = 10 - (10 % 1) = 10 - 0 = 10

模拟器测试下，结果也是 10

image

你方便方便把整个宏展开步骤拆一下嘛？看看具体哪个环节出的问题

@guoweilkd
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你测试的不是最新代码?最新代码的这两个宏是

#define FDB_ALIGN(size, align)                    ((size + align - 1) - ((size + align -1) % align))
/* align by write granularity */
#define FDB_WG_ALIGN(size)                        (FDB_ALIGN(size, (FDB_WRITE_GRAN + 7)/8))

后面的 ((size + align -1) % align)展开后% 和/的完整性会被打乱
FDB_WG_ALIGN(10)的展开结果如下: 10 + 0 % 15 / 8 = 10 /8 = 1, (size + align - 1) = 10, 所以 ((size + align - 1) - ((size + align -1) % align)) = 9

@armink
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@armink armink commented on 3e441f6 Oct 12, 2023

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👍 感谢反馈，确实是这个问题，给 入参 都加上括号就没问题了，类似下面这样

image

方便的话，可以帮忙提交个 PR 修正下哈

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