[ECOS] bit band macro names from Cortex-M3

[Bernard Fouché]

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


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