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| | avr-libc: Frequently Asked Questions |
 | | Bitwise operations in Standard C will automatically promote their operands to an int, which is (by default) 16 bits in avr-gcc. |
 | | While the device documentation provides mnemonic names for the various bits in the IO registers, and the AVR device-specific IO definitions reflect these names in definitions for numerical constants, a way is needed to convert a bit number (usually within a byte register) into a byte value that can be assigned directly to the register. |
 | | With respect to the standard, this sentence is somewhat simplified (because the standard allows for machines where the actual bit pattern used differs from all bits being 0), but for the AVR target, in general, all integer-type variables are set to 0, all pointers to a NULL pointer, and all floating-point variables to 0.0. |
| www.nongnu.org /avr-libc/user-manual/FAQ.html |
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