Bit access macros with bit-banding support for Cortex-M based CPUs. More...

Detailed Description

Bit access macros with bit-banding support for Cortex-M based CPUs.

Author: Joakim Nohlgård joaki.nosp@m.m.no.nosp@m.hlgar.nosp@m.d@ei.nosp@m.stec..nosp@m.se

Definition in file bit.h.

#include <stdint.h>
#include "cpu.h"

Include dependency graph for bit.h:

#define	CPU_HAS_BITBAND 1 \|\| 0 (1 if CPU implements bit-banding, 0 if not)
	Flag to check if the CPU has hardware bit band support.

#define	CPU_HAS_SRAM_BITBAND 1 \|\| 0
	Flag to check if bit-banding is supported for all of SRAM.

Bit manipulation functions
static volatile void *	bitband_addr (volatile void *ptr, uintptr_t bit)
	Convert bit band region address and bit number to bit band alias address.

static void	bit_set32 (volatile uint32_t *ptr, uint8_t bit)
	Set a single bit in the 32 bit word pointed to by `ptr`.

static void	bit_set16 (volatile uint16_t *ptr, uint8_t bit)
	Set a single bit in the 16 bit word pointed to by `ptr`.

static void	bit_set8 (volatile uint8_t *ptr, uint8_t bit)
	Set a single bit in the 8 bit byte pointed to by `ptr`.

static void	bit_clear32 (volatile uint32_t *ptr, uint8_t bit)
	Clear a single bit in the 32 bit word pointed to by `ptr`.

static void	bit_clear16 (volatile uint16_t *ptr, uint8_t bit)
	Clear a single bit in the 16 bit word pointed to by `ptr`.

static void	bit_clear8 (volatile uint8_t *ptr, uint8_t bit)
	Clear a single bit in the 8 bit byte pointed to by `ptr`.

static bool	bit_check32 (volatile uint32_t *ptr, uint8_t bit)
	Checks if a single bit in the 32 bit word pointed to by `ptr` is set.

static bool	bit_check16 (volatile uint16_t *ptr, uint8_t bit)
	Checks if a single bit in the 16 bit word pointed to by `ptr` is set.

static bool	bit_check8 (volatile uint8_t *ptr, uint8_t bit)
	Checks if a single bit in the 8 bit byte pointed to by `ptr` is set.

Macro Definition Documentation

◆ CPU_HAS_BITBAND

#define CPU_HAS_BITBAND 1 || 0 (1 if CPU implements bit-banding, 0 if not)

Flag to check if the CPU has hardware bit band support.

Definition at line 37 of file bit.h.

◆ CPU_HAS_SRAM_BITBAND

#define CPU_HAS_SRAM_BITBAND 1 || 0

Flag to check if bit-banding is supported for all of SRAM.

Bit-banding in SRAM is only supported (if available at all) for a 1 MiB region in the address space. If not all of SRAM is mapped there, it is safest to not use bit-banding at all. Luckily, only few vendors decided to implement partially broken bit-banding.

Return values

1	All of SRAM is bit-banding capable
0	(At least one part) SRAM is not bit-banding capable

Definition at line 49 of file bit.h.

Function Documentation

◆ bit_check16()

static bool bit_check16	(	volatile uint16_t *	ptr,
		uint8_t	bit
	)

inlinestatic

Checks if a single bit in the 16 bit word pointed to by ptr is set.

The effect is the same as for the following snippet:

*ptr & (1 << bit);

Parameters

[in]	ptr	pointer to target word
[in]	bit	bit number within the word

Definition at line 229 of file bit.h.

◆ bit_check32()

static bool bit_check32	(	volatile uint32_t *	ptr,
		uint8_t	bit
	)

inlinestatic

Checks if a single bit in the 32 bit word pointed to by ptr is set.

The effect is the same as for the following snippet:

*ptr & (1 << bit);

Parameters

[in]	ptr	pointer to target word
[in]	bit	bit number within the word

Definition at line 212 of file bit.h.

◆ bit_check8()

static bool bit_check8	(	volatile uint8_t *	ptr,
		uint8_t	bit
	)

inlinestatic

Checks if a single bit in the 8 bit byte pointed to by ptr is set.

The effect is the same as for the following snippet:

*ptr & (1 << bit);

Parameters

[in]	ptr	pointer to target byte
[in]	bit	bit number within the byte

Definition at line 246 of file bit.h.

◆ bit_clear16()

static void bit_clear16	(	volatile uint16_t *	ptr,
		uint8_t	bit
	)

inlinestatic

Clear a single bit in the 16 bit word pointed to by ptr.

The effect is the same as for the following snippet:

*ptr &= ~(1 << bit);

There is a read-modify-write cycle occurring within the core, but this cycle is atomic and can not be disrupted by IRQs

Parameters

[in]	ptr	pointer to target word
[in]	bit	bit number within the word

Definition at line 175 of file bit.h.

◆ bit_clear32()

static void bit_clear32	(	volatile uint32_t *	ptr,
		uint8_t	bit
	)

inlinestatic

Clear a single bit in the 32 bit word pointed to by ptr.

The effect is the same as for the following snippet:

*ptr &= ~(1 << bit);

There is a read-modify-write cycle occurring within the core, but this cycle is atomic and can not be disrupted by IRQs

Parameters

[in]	ptr	pointer to target word
[in]	bit	bit number within the word

Definition at line 155 of file bit.h.

◆ bit_clear8()

static void bit_clear8	(	volatile uint8_t *	ptr,
		uint8_t	bit
	)

inlinestatic

Clear a single bit in the 8 bit byte pointed to by ptr.

The effect is the same as for the following snippet:

*ptr &= ~(1 << bit);

There is a read-modify-write cycle occurring within the core, but this cycle is atomic and can not be disrupted by IRQs

Parameters

[in]	ptr	pointer to target byte
[in]	bit	bit number within the byte

Definition at line 195 of file bit.h.

◆ bit_set16()

static void bit_set16	(	volatile uint16_t *	ptr,
		uint8_t	bit
	)

inlinestatic

Set a single bit in the 16 bit word pointed to by ptr.

The effect is the same as for the following snippet:

*ptr |= (1 << bit);

There is a read-modify-write cycle occurring within the core, but this cycle is atomic and can not be disrupted by IRQs

Parameters

[in]	ptr	pointer to target word
[in]	bit	bit number within the word

Definition at line 115 of file bit.h.

◆ bit_set32()

static void bit_set32	(	volatile uint32_t *	ptr,
		uint8_t	bit
	)

inlinestatic

Set a single bit in the 32 bit word pointed to by ptr.

The effect is the same as for the following snippet:

*ptr |= (1 << bit);

There is a read-modify-write cycle occurring within the core, but this cycle is atomic and can not be disrupted by IRQs

Parameters

[in]	ptr	pointer to target word
[in]	bit	bit number within the word

Definition at line 95 of file bit.h.

◆ bit_set8()

static void bit_set8	(	volatile uint8_t *	ptr,
		uint8_t	bit
	)

inlinestatic

Set a single bit in the 8 bit byte pointed to by ptr.

The effect is the same as for the following snippet:

*ptr |= (1 << bit);

There is a read-modify-write cycle occurring within the core, but this cycle is atomic and can not be disrupted by IRQs

Parameters

[in]	ptr	pointer to target byte
[in]	bit	bit number within the byte

Definition at line 135 of file bit.h.

◆ bitband_addr()

static volatile void * bitband_addr	(	volatile void *	ptr,
		uintptr_t	bit
	)

inlinestatic

Convert bit band region address and bit number to bit band alias address.

Parameters

[in]	ptr	base address in non bit banded memory
[in]	bit	bit number within the word

Returns: Address of the bit within the bit band memory region

Definition at line 74 of file bit.h.

Detailed Description

Bit manipulation functions

Macro Definition Documentation

◆ CPU_HAS_BITBAND

◆ CPU_HAS_SRAM_BITBAND

Function Documentation

◆ bit_check16()

◆ bit_check32()

◆ bit_check8()

◆ bit_clear16()

◆ bit_clear32()

◆ bit_clear8()

◆ bit_set16()

◆ bit_set32()

◆ bit_set8()

◆ bitband_addr()