I don't fully understand the addressig mode od AVR ATtinyxxx 0-Series.
The following dissasembled code shows:
r = ~(r ^ 0b10101010);
0x78: LDS R25, 0x00 0x79: CPI R24, 0xF1 0x7A: LDI R24, 0x55 0x7B: EOR R24, R25 0x7C: STS 0x00, R24 0x7D: CPI R24, 0xF1
When I step the ASM rows, the program jumps from 0x78 to 0x7A without stopping at 0x79 row. Maybe it has something to do with the fact that LDS variable address for AVR 0-Series is not 32 bits but only 16 bits.