uint64 Filesize

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Thu, 2015-09-03 05:03
#1
mritter0
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uint64 Filesize

This is my first time using uint64 to handle file sizes >2GB. I am having a terrible time converting it to a readable value to show as text.

Code snippet I am using to convert 3534359552 to GB

  1. uint64 size, value;
  2.  
  3. // size=3534359552;
  4. value=(size/1073741824*100000)/100000;  // = 3.291628......  rounded to 3
  5.  
  6. - or -
  7.  
  8. value=(size*100)/1073741824;    // = 329.16288.... rounded to 329

How to I format it to be like: 3.29 GB

This crashes:

  1. IUtility->SNPrintf(BTUBuffer,15,"%llu%s%02llu GB",value,Locale->loc_DecimalPoint,value % 100);
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Thu, 2015-09-03 10:46
salass00
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Re: uint64 Filesize 
  1. /* Compile with:
  2.      gcc -O2 -Wall -Werror -Wwrite-strings -D__USE_INLINE__ -o uint64-filesize uint64-filesize.c -lauto
  3. */
  4. #include <proto/dos.h>
  5. #include <proto/utility.h>
  6. #include <proto/locale.h>
  7.  
  8. int main(void) {
  9.     struct Locale *locale;
  10.     char buffer[16];
  11.     uint64 size = 3534359552ULL;
  12.     uint64 value = (size*100 + (1024*1024*1024/2)) / (1024*1024*1024);
  13.  
  14.     locale = OpenLocale(NULL);
  15.  
  16.     SNPrintf(buffer, sizeof(buffer), "%llu%s%s%02llu GB", value / 100,
  17.         locale ? locale->loc_DecimalPoint : ".", "", value % 100);
  18.     Printf("Size: %s\n", buffer);
  19.  
  20.     CloseLocale(locale);
  21.  
  22.     return RETURN_OK;
  23. }

There is a bit of a problem with 64-bit values and RawDoFmt() based functions like SNPrintf() in that while RawDoFmt() doesn't expect any alignment the C compiler aligns them to 64-bit so that's why I've added an extra %s and "" to work around this.

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Thu, 2015-09-03 10:47
(Reply to #2)
salass00
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Re: uint64 Filesize

BTW since the fraction part is limited to 0-99 there is strictly no need to use a 64-bit value there so the SNPrintf() could be changed to:

  1. SNPrintf(buffer, sizeof(buffer), "%llu%s%02lu GB", value / 100,
  2.         locale ? locale->loc_DecimalPoint : ".", (uint32)(value % 100));
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Fri, 2015-09-04 01:44
mritter0
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Re: uint64 Filesize

Thank you. Works just like I needed.

Are there any other 64bit issues I need to look out for?

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Tue, 2015-09-08 10:39
(Reply to #4)
salass00
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Re: uint64 Filesize


Are there any other 64bit issues I need to look out for?

Not that I can think of.

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