In HardwareSerial, don't use int for buffer indices
The index attributes have been uint8_t for a while, so there is no point in using int for local variables. This should allow the compiler to generate slightly more efficient code, but (at least on gcc 4.8.2) it also confuses the register allocator, causing this change to increase code size by 2 bytes instead due to extra push/pop instructions (but this will probably change in the future if the compiler improves).
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@ -171,7 +171,7 @@ int HardwareSerial::read(void)
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return -1;
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} else {
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unsigned char c = _rx_buffer[_rx_buffer_tail];
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_rx_buffer_tail = (unsigned int)(_rx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
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_rx_buffer_tail = (uint8_t)(_rx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
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return c;
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}
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}
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@ -207,7 +207,7 @@ size_t HardwareSerial::write(uint8_t c)
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sbi(*_ucsra, TXC0);
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return 1;
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}
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int i = (_tx_buffer_head + 1) % SERIAL_BUFFER_SIZE;
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uint8_t i = (_tx_buffer_head + 1) % SERIAL_BUFFER_SIZE;
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// If the output buffer is full, there's nothing for it other than to
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// wait for the interrupt handler to empty it a bit
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