Another way to specify bit-band area is by means of sections. Then you declare ordinary variables with section attribute and ld will allocate just enough memory for bit-band space.
Ilija On 08.12.2011 09:53, Bernard Fouché wrote: > Hi. > > I'd like to be get suggestions about suitable macro names for bit band > operations on the Cortex-M3. > > Since this is a MCU option, they should be defined per MCU. > > Actually working on the LPC17XX, I have defined: > > //============================================================================= > > // LPC17XX supports CORTEX-M3 bit banding option > #define CYGHWR_HAL_LPC17XX_BITBAND_SRAM_PHY 0x20000000 // > to 0x200FFFFF (1 meg) > #define CYGHWR_HAL_LPC17XX_BITBAND_SRAM_BB 0x22000000 > // Convert SRAM address > #define CYGHWR_HAL_LPC17XX_BITBAND_SRAM(address,bit)\ > ((CYGHWR_HAL_LPC17XX_BITBAND_SRAM_BB +\ > (address-CYGHWR_HAL_LPC17XX_BITBAND_SRAM_PHY)*32 +\ > (bit*4))) > > #define CYGHWR_HAL_LPC17XX_BITBAND_PERI_PHY 0x40000000 // > to 0x400FFFFF > #define CYGHWR_HAL_LPC17XX_BITBAND_PERI_BB 0x42000000 > // Convert PERIPHERAL address > #define CYGHWR_HAL_LPC17XX_BITBAND_PERI(address,bit)\ > ((CYGHWR_HAL_LPC17XX_BITBAND_PERI_BB +\ > (address-CYGHWR_HAL_LPC17XX_BITBAND_PERI_PHY)*32 +\ > (bit*4))) > > Use case: > > // add channel to pool > *(volatile cyg_uint32 > *)CYGHWR_HAL_LPC17XX_BITBAND_PERI(ADC_CR,1<<chan->channel)=1; > > Another possibility would be to provide higher level macros for bit > set/test/read-modify-write operations and have these macros to use bit > band if the targets support them. However bit band operations will > probably be used only in driver code specific to a MCU familly and the > driver designer may prefer to explicitly states when a bit band > operation is used. > > Since I'll provide some drivers in the next weeks, it would be nice if > these drivers already use macro names acceptable for eCos maintainers. > > Bernard > > -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
