如何将 38 位字节数组转换为 ASCII 十进制

发布于 2024-10-12 13:35:21 字数 974 浏览 14 评论 0原文

我正在编写一个例程和一个 AVR ATMEGA88，以使用 TI TM3705A 芯片读取 FDX RFID 标签，并通过 UART 将其传输到另一个处理器。该芯片使用 15625 波特率，而另一个处理器将以 19200 波特率接收数据。

这个想法是读取传入的数据（38 位 ID 号 - 例如 00 11 E3 D6 7C），对其进行 CRC 校验，然后将其输出为友好的 12 位十进制数 (000300144252)，代表标签的唯一 ID。

到目前为止，我在数组中有这个 38 位数字：

我感兴趣的实际数字位于元素 2:6 中。 2 个 MSB 的编号。 6 应被忽略，因为它们是下一个数据块的开始。

i   Dec Hex Bin
0   80  50  01010000
1   126 7E  01111110
2   124 7C  01111100
3   214 D6  11010110
4   227 E3  11100011
5   17  11  00010001
6   192 C0  11000000
7   237 ED  11101101
8   0   00  00000000
9   128 80  10000000
10  97  61  01100001
11  103 67  01100111
12  126 7E  01111110
13  0   00  00000000
14  0   00  00000000

我正在寻找一种有效的方法来将数组中的字节输出为十进制“000300144252”。

我尝试将其打包成 long long 类型，然后使用 sprintf %d 但它似乎因 temp = data << 而窒息。例如32。我不知道 sprintf 是否能处理这个大小的数字。我承认我已经被 C# 和其他懒惰语言宠坏了:)

有没有一种方法可以“随时”转换为十进制 - 换句话说，从最高有效数字 (6) 读取并在UART上输出十进制ASCII数字，然后5,4,3,2没有大的中间缓冲区等？这些芯片的内存有点受限。

原文

I am writing a routine and an AVR ATMEGA88 to read FDX RFID tags using the TI TM3705A chip and transmit that over UART to another processor. This chip uses 15625 baud while the other processor will receive the data at 19200 baud.

The idea is to read the incoming data (38 bits of ID number - e.g. 00 11 E3 D6 7C), CRC check it and then output it as a friendly 12 digit decimal number (000300144252) that represents the unique ID of the tag.

So far I have this 38 bit number in an array:

The actual number I'm interested in sits in elements 2:6. The 2 MSB's of no. 6 should be ignored because they are the start of the next block of data.

i   Dec Hex Bin
0   80  50  01010000
1   126 7E  01111110
2   124 7C  01111100
3   214 D6  11010110
4   227 E3  11100011
5   17  11  00010001
6   192 C0  11000000
7   237 ED  11101101
8   0   00  00000000
9   128 80  10000000
10  97  61  01100001
11  103 67  01100111
12  126 7E  01111110
13  0   00  00000000
14  0   00  00000000

I'm looking for an efficient way to output the bytes in the array as decimal "000300144252".

I've tried packing it into a long long type and then use sprintf %d but it seems to choke on temp = data << 32 for example. I don't know if sprintf will even handle that size number yet. I'll admit I've gotten really spoiled with C# and other lazy languages for this kind of stuff :)

Is there a way to convert to decimal "as you go" - in other words, read from the most significant digit (6) and output the decimal ASCII digits on the UART, then 5,4,3,2 without large intermediate buffers and the like? Memory is a little constrained on these chips.

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枕头说它不想醒 2024-10-19 13:35:21

转换为十进制的计算量很大 - 无论您自己执行还是将其委托给库函数（例如 sprintf()）都不会改变它。这里更复杂的是它是一个相对较大的值：38 位，比 32 位大。

通过 sprintf()，使用 "%lld" 打印 long long。如果编译器支持 long long 类型，但 sprintf() 不支持，那么您可以手动完成：

static void
convert_to_decimal(char[] dst, unsigned long long src)
{
    int i;

    for (i = 0; i < 12; i ++) {
        dst[11 - i] = '0' + (int)(src % 10);
        src /= 10;
    }
    dst[12] = 0;
}

此函数在 中写出 12 个字符的结果dst[]（以 NUL 结尾）。请注意，这意味着除以 10，编译器会将其转换为包含相对复杂的函数。

如果您的编译器不支持 long long 类型（或在尝试进行除法时遇到困难），那么您将必须自己实现该操作，这将需要一些数学知识。最终，本文可能有用，也可能没有用。

Conversion to decimal is computationally expensive -- whether you do it yourself or delegate it to a library function such as sprintf() does not change it. What makes it more complex here is that it is a relatively large value: 38 bits, that's bigger than 32 bits.

With sprintf(), use "%lld" to print a long long. If the compiler supports the long long type but sprintf() does not, then you can do it by hand:

static void
convert_to_decimal(char[] dst, unsigned long long src)
{
    int i;

    for (i = 0; i < 12; i ++) {
        dst[11 - i] = '0' + (int)(src % 10);
        src /= 10;
    }
    dst[12] = 0;
}

This function writes out the 12-char result in dst[] (with a terminating NUL). Note that this implies a division by 10, which the compiler will translate into the inclusion of a relatively complex function.

If your compiler does not support the long long type (or chokes on trying to make a division) then you will have to implement that operation yourself, which will require a bit of mathematical knowledge. Ultimately, this article may be useful -- or not.

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黎夕旧梦 2024-10-19 13:35:21

经过大量的搜索和反复试验，我找到了解决方案。

我误解了我看到的错误，托马斯是对的。当添加到我自己的功能中时，该功能对于芯片来说太大了。

显而易见的选择并没有什么用处，但我将在这里列出它们，以帮助其他菜鸟遇到这个问题时。

itoa() - 16 位和 ultoa() - 32 位已实现，但太小。

sprintf(%d) 太小，并且 sprintf(%lld) 未在 WinAVR (AVR-GCC) 中实现。

此代码有效（有警告）：

void main()
{
    unsigned long long tagid;
    char tagid_str[12];

    tagid = 109876543210ull

    convert_to_decimal(tagid_str, tagid);
}

void convert_to_decimal(char* dst, unsigned long long src) 
{     
    int i;
    for (i = 0; i < 12; i ++) 
    {         
        dst[11 - i] = '0' + (int)(src % 10);
        src /= 10;     
    }     

    dst[12] = 0; 
}

但是看看统计数据：

程序：7358 字节（89.8% 已满）
（.text + .data + .bootloader）

数据：256 字节（25.0% 已满）
(.data + .bss + .noinit)

罪魁祸首是 % 运算符。我无法解释为什么将它与 long long 一起使用会生成近 8k 的代码！

这是一个可行的替代方案。我将其修改为仅使用 unsigned long long（64 位），最多 12 位十进制数字，以适合我正在使用的 RFID 读取器格式。

void main()
{
    unsigned long long tagid;
    char tagid_str[12];

    tagid = 000000000000ull;
    ulltostr((unsigned long long)tagid, tagid_str);

    tagid = 000000000001ull;
    ulltostr((unsigned long long)tagid, tagid_str);

    tagid = 109876543210ull;
    ulltostr((unsigned long long)tagid, tagid_str);

    tagid = 900000000000ull;
    ulltostr((unsigned long long)tagid, tagid_str);

    tagid = 999999999999ull;
    ulltostr((unsigned long long)tagid, tagid_str);
}

//http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=31199

void ulltostr(unsigned long long val, char *s ) 
{ 
  char *p; 
  unsigned char d, i; 
  unsigned char zero; 
  unsigned long long test; 
  unsigned long long uval = val; 

  p = s; 

  zero = 1; 

  i = 12; 
  do{ 
    i--;    
    if ( i==0)   test =10; 
    else if ( i==1) test =100; 
    else if ( i==2) test =1000; 
    else if ( i==3) test =10000; 
    else if ( i==4) test =100000; 
    else if ( i==5) test =1000000; 
    else if ( i==6) test =10000000; 
    else if ( i==7) test =100000000; 
    else if ( i==8) test =1000000000; 
    else if ( i==9) test =10000000000; 
    else if ( i==10) test=100000000000; 
    else if ( i==11) test=1000000000000; 
    else if ( i==12) test=10000000000000; 

    for( d = '0'; uval >= test; uval -= test ) 
    { 
      d++; 
      zero = 0; 
    } 
    if( zero == 0 ) 
      *p++ = d ; 
  }while( i ); 

  *p++ = (unsigned char)uval + '0'; 
}

统计数据：

程序：758 字节（9.3% 已满）
（.text + .data + .bootloader）

数据：0 字节（0.0% 已满）
（.data + .bss + .noinit）

好多了 :)

我大部分时间都花在 Douglas Jones，但答案最终来自 AVR 怪胎。

After a lot of searching and trial and error, I found a solution.

I misinterpreted the error I was seeing and Thomas is right. The function was too big for the chip when added to my own functions.

The obvious choices didn't go anywhere, but I'll list them here to help other noobs when they hit this problem.

itoa() - 16 bit and ultoa() - 32 bit are implemented but too small.

sprintf(%d) is too small and sprintf(%lld) is not implemented in WinAVR (AVR-GCC).

This code works (with caveat):

void main()
{
    unsigned long long tagid;
    char tagid_str[12];

    tagid = 109876543210ull

    convert_to_decimal(tagid_str, tagid);
}

void convert_to_decimal(char* dst, unsigned long long src) 
{     
    int i;
    for (i = 0; i < 12; i ++) 
    {         
        dst[11 - i] = '0' + (int)(src % 10);
        src /= 10;     
    }     

    dst[12] = 0; 
}

But look at the stats:

Program: 7358 bytes (89.8% Full)
(.text + .data + .bootloader)

Data: 256 bytes (25.0% Full)
(.data + .bss + .noinit)

The culprit is the % operator. I can't explain why using it with a long long generates almost 8k of code!

Here is a working alternative. I modified it to only use unsigned long long (64 bits) up to 12 decimal digits to fit the RFID reader format I'm using.

void main()
{
    unsigned long long tagid;
    char tagid_str[12];

    tagid = 000000000000ull;
    ulltostr((unsigned long long)tagid, tagid_str);

    tagid = 000000000001ull;
    ulltostr((unsigned long long)tagid, tagid_str);

    tagid = 109876543210ull;
    ulltostr((unsigned long long)tagid, tagid_str);

    tagid = 900000000000ull;
    ulltostr((unsigned long long)tagid, tagid_str);

    tagid = 999999999999ull;
    ulltostr((unsigned long long)tagid, tagid_str);
}

//http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=31199

void ulltostr(unsigned long long val, char *s ) 
{ 
  char *p; 
  unsigned char d, i; 
  unsigned char zero; 
  unsigned long long test; 
  unsigned long long uval = val; 

  p = s; 

  zero = 1; 

  i = 12; 
  do{ 
    i--;    
    if ( i==0)   test =10; 
    else if ( i==1) test =100; 
    else if ( i==2) test =1000; 
    else if ( i==3) test =10000; 
    else if ( i==4) test =100000; 
    else if ( i==5) test =1000000; 
    else if ( i==6) test =10000000; 
    else if ( i==7) test =100000000; 
    else if ( i==8) test =1000000000; 
    else if ( i==9) test =10000000000; 
    else if ( i==10) test=100000000000; 
    else if ( i==11) test=1000000000000; 
    else if ( i==12) test=10000000000000; 

    for( d = '0'; uval >= test; uval -= test ) 
    { 
      d++; 
      zero = 0; 
    } 
    if( zero == 0 ) 
      *p++ = d ; 
  }while( i ); 

  *p++ = (unsigned char)uval + '0'; 
}

And the stats:

Program: 758 bytes (9.3% Full)
(.text + .data + .bootloader)

Data: 0 bytes (0.0% Full)
(.data + .bss + .noinit)

Much better :)

I spent most of my time with Douglas Jones, but the answer finally came from AVR Freaks.

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