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Asked: 2026-05-14T01:10:44+00:00

I am new to shifting bits, but I am trying to debug the following

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I am new to shifting bits, but I am trying to debug the following snippet:

if (!(strcmp(arr[i].GetValType(), "f64")))
 {
        dem_content_buff[BytFldPos] = tmp_data;
     dem_content_buff[BytFldPos + 1] =  tmp_data >> 8;
     dem_content_buff[BytFldPos + 2] = tmp_data >> 16;
     dem_content_buff[BytFldPos + 3] = tmp_data >> 24;
     dem_content_buff[BytFldPos + 4] = tmp_data >> 32;
     dem_content_buff[BytFldPos + 5] = tmp_data >> 40;
     dem_content_buff[BytFldPos + 6] = tmp_data >> 48;
     dem_content_buff[BytFldPos + 7] = tmp_data >> 56;
        }

I am getting a warning saying the lines with “32” to “56” have a shift count that is too large. The “f64” in the predicate just means that the data should be 64bit data.

How should this be done?

edit:

I should have put more of the code in.

tmp_data = simulated_data[index_data];

if (!(strcmp(dems[i].GetValType(), "s32")))

{
dem_content_buff[BytFldPos] = tmp_data;
dem_content_buff[BytFldPos + 1] = tmp_data >> 8;
dem_content_buff[BytFldPos + 2] = tmp_data >> 16;
dem_content_buff[BytFldPos + 3] = tmp_data >> 24;
}

if (!(strcmp(dems[i].GetValType(), “f64”)))
{
dem_content_buff[BytFldPos] = tmp_data;
dem_content_buff[BytFldPos + 1] = tmp_data >> 8;
dem_content_buff[BytFldPos + 2] = tmp_data >> 16;
dem_content_buff[BytFldPos + 3] = tmp_data >> 24;
dem_content_buff[BytFldPos + 4] = tmp_data >> 32;
dem_content_buff[BytFldPos + 5] = tmp_data >> 40;
dem_content_buff[BytFldPos + 6] = tmp_data >> 48;
dem_content_buff[BytFldPos + 7] = tmp_data >> 56;
}

So, dem_content_buff right now only holds ints. Can I not use this array for the 64 bit data either?

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1 Answer

  1. Editorial Team

    Make sure to use 64bit long type for the tmp_data as was suggested before the unsinged long long should work, but check your compiler and architecture documentation.

    The code should look like this. Also, make sure that your demp_content_buff is declared as unsigned char * or unsigned char [].

    Then change your code to:

    if (!(strcmp(arr[i].GetValType(), "f64")))
    {
        dem_content_buff[BytFldPos] =  ( tmp_data & 0xff );
        dem_content_buff[BytFldPos + 1] =  (tmp_data >> 8 ) & 0xff ;
        dem_content_buff[BytFldPos + 2] =  (tmp_data >> 16) & 0xff ;
        dem_content_buff[BytFldPos + 3] =  (tmp_data >> 24) & 0xff;
        dem_content_buff[BytFldPos + 4] =  (tmp_data >> 32) & 0xff;
        dem_content_buff[BytFldPos + 5] =  (tmp_data >> 40) & 0xff;
        dem_content_buff[BytFldPos + 6] =  (tmp_data >> 48) & 0xff;
        dem_content_buff[BytFldPos + 7] =  (tmp_data >> 56) & 0xff;
        }
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