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IAR Embedded Workbench ARM compiler

Raimundo

Hi, I'm using IAR Embedded Workbench ARM are: being int a; and unsigned char b = 0x03; a = ~ b; should not be 0xfc and not 0xfffffffc? Is this a bug or is it deliberate?

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  • 0

    Hi,

    as the results, the compiler is right.

    Because the operations are performed with the type matching,

    a = ~b;

    is identical to

    a = (int)~b; .

    Also,

    a = (int)~b;

    means

    if(~b[7]==1) a = {0xffffff, ~b[7:0]};

    else         a = {0x000000, ~b[7:0]}; .

    If you want to put 0xfc into the variable a, you should write as the following.

    a = (unsigned char)~b;

    Best regards,

    Yasuhiko Koumoto.

Reply
  • 0

    Hi,

    as the results, the compiler is right.

    Because the operations are performed with the type matching,

    a = ~b;

    is identical to

    a = (int)~b; .

    Also,

    a = (int)~b;

    means

    if(~b[7]==1) a = {0xffffff, ~b[7:0]};

    else         a = {0x000000, ~b[7:0]}; .

    If you want to put 0xfc into the variable a, you should write as the following.

    a = (unsigned char)~b;

    Best regards,

    Yasuhiko Koumoto.

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