BUS - Bitfield Read/Write

Description

BUS register and RAM bit/field read/write API.

API to perform bit-band and field set/clear access to RAM and peripherals.

Functions

void BUS_RamBitWrite (volatile uint32_t *addr, unsigned int bit, unsigned int val)
Perform a single-bit write operation on a 32-bit word in RAM.
unsigned int BUS_RamBitRead (volatile const uint32_t *addr, unsigned int bit)
Perform a single-bit read operation on a 32-bit word in RAM.
void BUS_RegBitWrite (volatile uint32_t *addr, unsigned int bit, unsigned int val)
Perform a single-bit write operation on a peripheral register.
unsigned int BUS_RegBitRead (volatile const uint32_t *addr, unsigned int bit)
Perform a single-bit read operation on a peripheral register.
void BUS_RegMaskedSet (volatile uint32_t *addr, uint32_t mask)
Perform a masked set operation on a peripheral register address.
void BUS_RegMaskedClear (volatile uint32_t *addr, uint32_t mask)
Perform a masked clear operation on the peripheral register address.
void BUS_RegMaskedWrite (volatile uint32_t *addr, uint32_t mask, uint32_t val)
Perform peripheral register masked write.
uint32_t BUS_RegMaskedRead (volatile const uint32_t *addr, uint32_t mask)
Perform a peripheral register masked read.

Function Documentation

BUS_RamBitWrite()

void BUS_RamBitWrite ( volatile uint32_t * addr,
unsigned int bit,
unsigned int val
)
inline

Perform a single-bit write operation on a 32-bit word in RAM.

This function uses Cortex-M bit-banding hardware to perform an atomic read-modify-write operation on a single bit write on a 32-bit word in RAM. See the reference manual for more details about bit-banding.

Note
This function is atomic on Cortex-M cores with bit-banding support. Bit- banding is a multicycle read-modify-write bus operation. RAM bit-banding is performed using the memory alias region at BITBAND_RAM_BASE.
Parameters
[in] addr An ddress of a 32-bit word in RAM.
[in] bit A bit position to write, 0-31.
[in] val A value to set bit to, 0 or 1.

BUS_RamBitRead()

unsigned int BUS_RamBitRead ( volatile const uint32_t * addr,
unsigned int bit
)
inline

Perform a single-bit read operation on a 32-bit word in RAM.

This function uses Cortex-M bit-banding hardware to perform an atomic read operation on a single register bit. See the reference manual for more details about bit-banding.

Note
This function is atomic on Cortex-M cores with bit-banding support. RAM bit-banding is performed using the memory alias region at BITBAND_RAM_BASE.
Parameters
[in] addr RAM address.
[in] bit A bit position to read, 0-31.
Returns
The requested bit shifted to bit position 0 in the return value.

BUS_RegBitWrite()

void BUS_RegBitWrite ( volatile uint32_t * addr,
unsigned int bit,
unsigned int val
)
inline

Perform a single-bit write operation on a peripheral register.

This function uses Cortex-M bit-banding hardware to perform an atomic read-modify-write operation on a single register bit. See the reference manual for more details about bit-banding.

Note
This function is atomic on Cortex-M cores with bit-banding support. Bit- banding is a multicycle read-modify-write bus operation. Peripheral register bit-banding is performed using the memory alias region at BITBAND_PER_BASE.
Parameters
[in] addr A peripheral register address.
[in] bit A bit position to write, 0-31.
[in] val A value to set bit to, 0 or 1.

BUS_RegBitRead()

unsigned int BUS_RegBitRead ( volatile const uint32_t * addr,
unsigned int bit
)
inline

Perform a single-bit read operation on a peripheral register.

This function uses Cortex-M bit-banding hardware to perform an atomic read operation on a single register bit. See the reference manual for more details about bit-banding.

Note
This function is atomic on Cortex-M cores with bit-banding support. Peripheral register bit-banding is performed using the memory alias region at BITBAND_PER_BASE.
Parameters
[in] addr A peripheral register address.
[in] bit A bit position to read, 0-31.
Returns
The requested bit shifted to bit position 0 in the return value.

BUS_RegMaskedSet()

void BUS_RegMaskedSet ( volatile uint32_t * addr,
uint32_t mask
)
inline

Perform a masked set operation on a peripheral register address.

A peripheral register masked set provides a single-cycle and atomic set operation of a bit-mask in a peripheral register. All 1s in the mask are set to 1 in the register. All 0s in the mask are not changed in the register. RAMs and special peripherals are not supported. See the reference manual for more details about the peripheral register field set.

Note
This function is single-cycle and atomic on cores with peripheral bit set and clear support. It uses the memory alias region at PER_BITSET_MEM_BASE.
Parameters
[in] addr A peripheral register address.
[in] mask A mask to set.

BUS_RegMaskedClear()

void BUS_RegMaskedClear ( volatile uint32_t * addr,
uint32_t mask
)
inline

Perform a masked clear operation on the peripheral register address.

A peripheral register masked clear provides a single-cycle and atomic clear operation of a bit-mask in a peripheral register. All 1s in the mask are set to 0 in the register. All 0s in the mask are not changed in the register. RAMs and special peripherals are not supported. See the reference manual for more details about the peripheral register field clear.

Note
This function is single-cycle and atomic on cores with peripheral bit set and clear support. It uses the memory alias region at PER_BITCLR_MEM_BASE.
Parameters
[in] addr A peripheral register address.
[in] mask A mask to clear.

BUS_RegMaskedWrite()

void BUS_RegMaskedWrite ( volatile uint32_t * addr,
uint32_t mask,
uint32_t val
)
inline

Perform peripheral register masked write.

This function first reads the peripheral register and updates only bits that are set in the mask with content of val. Typically, the mask is a bit-field in the register and the value val is within the mask.

Note
The read-modify-write operation is executed in a critical section to guarantee atomicity. Note that atomicity can only be guaranteed if register is modified only by the core, and not by other peripherals (like DMA).
Parameters
[in] addr A peripheral register address.
[in] mask A peripheral register mask.
[in] val A peripheral register value. The value must be shifted to the correct bit position in the register corresponding to the field defined by the mask parameter. The register value must be contained in the field defined by the mask parameter. The register value is masked to prevent involuntary spillage.

BUS_RegMaskedRead()

uint32_t BUS_RegMaskedRead ( volatile const uint32_t * addr,
uint32_t mask
)
inline

Perform a peripheral register masked read.

Read an unshifted and masked value from a peripheral register.

Note
This operation is not hardware accelerated.