On Tuesday, 15 July 2014 at 19:48:23 UTC, Walter Bright wrote:
The one thing peek/poke doesn't offer is transitivity. C/C++
don't offer volatile transitivity either. I'm not at all sure
that anyone builds a data structure in memory-mapped registers,
so I'm not convinced this is a need.
Here's an example from the STM32F4 ARM Cortex-M peripheral
library:
#define __IO volatile
/**
* @brief DMA Controller
*/
typedef struct
{
__IO uint32_t CR; /*!< DMA stream x configuration register
*/
__IO uint32_t NDTR; /*!< DMA stream x number of data register
*/
__IO uint32_t PAR; /*!< DMA stream x peripheral address
register */
__IO uint32_t M0AR; /*!< DMA stream x memory 0 address
register */
__IO uint32_t M1AR; /*!< DMA stream x memory 1 address
register */
__IO uint32_t FCR; /*!< DMA stream x FIFO control register
*/
} DMA_Stream_TypeDef;
typedef struct
{
__IO uint32_t LISR; /*!< DMA low interrupt status register,
Address offset: 0x00 */
__IO uint32_t HISR; /*!< DMA high interrupt status register,
Address offset: 0x04 */
__IO uint32_t LIFCR; /*!< DMA low interrupt flag clear
register, Address offset: 0x08 */
__IO uint32_t HIFCR; /*!< DMA high interrupt flag clear
register, Address offset: 0x0C */
} DMA_TypeDef;
There are several hundreds lines of this stuff in the library.
It is used to model register banks. Each register bank roughly
corresponds to one of the embedded peripherals.
Mike
