SPI_BASE = 0x80
SPICR0  = SPI_BASE + 0x08
SPICR1  = SPI_BASE + 0x09
SPICR2  = SPI_BASE + 0x0a
SPIBR   = SPI_BASE + 0x0b
SPISR   = SPI_BASE + 0x0c
SPITXDR = SPI_BASE + 0x0d
SPIRXDR = SPI_BASE + 0x0e
SPICSR  = SPI_BASE + 0x0f

init:
        SPICR0 = 0xff
        SPICR1 = 0x80
        SPICR2 = 0xc0
        SPIBR  = 0x03
        SPICSR = 0x0f