what does this code mean in the context of a function?
(*(volatile unsigned long *)(spi_base[dev] + SSP_CR0)) = buf;
1.buf is already defined as : unsigned int buf ;
2. spi_base seems to be a global variable: const unsigned long spi_base[MAX_SPI] = {SSP0_BASE_ADDR,SSP1_BASE_ADDR};
3. and SSP_CR0 is defined as :
#define SSP_CR0 0x00