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Urgent: warning: #61-D: integer operation result is out of range

Murthy r

HI Friends,

I am using AT91SAM7SE512 controller,
i have configured the input in port B.while compiling the program i am getting this warning.

main.c(8): warning: #61-D: integer operation result is out of range
main.c(8): warning: #68-D: integer conversion resulted in a change of sign.

If anybody knows about this bug Please help me to rectify.

The code is

#define test (1<<31) //PB31

int main()
{ // Enable the clock of the PIOB for led and PIO for Switch

AT91F_PMC_EnablePeriphClock ( AT91C_BASE_PMC, 1 << AT91C_ID_PIOB) ; AT91F_PIO_CfgInput (AT91C_BASE_PIOB , test );

}
with regards,
Nanju...

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  • 0 in reply to Murthy r

    A 32-bit integer has exactly what out sounds like - 32 bits. They are numbered from 0 to 31, and for an unsigned integer represents the values 2^0 (=1) to 2^31 (=2147483648).

    For a signed integer, a system called two's complement is used. Half the capacity is used to store negative values, limiting the largest positive value to every bit but the last one, i.e. 2^0 + 2^1 + 2^2 + ... + 2^30 (=2147483647). A signed integer will the most significant bit set represents a negative value.

    Your operation (1<<31) would convert the positive number 1 into a negative value by moving the bit all the way into the last position, and the compiler complained. Specifically saying that the digit 1 was unsigned, by the suffix u (1u) tells the compiler that the integer should not be treated as a signed integer and that the most significant bit is available to be used without generating a warning.

    For more information about the two's complement format, see this link:
    en.wikipedia.org/.../Two's_complement

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  • 0 in reply to Murthy r

    A 32-bit integer has exactly what out sounds like - 32 bits. They are numbered from 0 to 31, and for an unsigned integer represents the values 2^0 (=1) to 2^31 (=2147483648).

    For a signed integer, a system called two's complement is used. Half the capacity is used to store negative values, limiting the largest positive value to every bit but the last one, i.e. 2^0 + 2^1 + 2^2 + ... + 2^30 (=2147483647). A signed integer will the most significant bit set represents a negative value.

    Your operation (1<<31) would convert the positive number 1 into a negative value by moving the bit all the way into the last position, and the compiler complained. Specifically saying that the digit 1 was unsigned, by the suffix u (1u) tells the compiler that the integer should not be treated as a signed integer and that the most significant bit is available to be used without generating a warning.

    For more information about the two's complement format, see this link:
    en.wikipedia.org/.../Two's_complement

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