Functions
void	__NOP (void)
	No Operation. More...

void	__WFI (void)
	Wait For Interrupt. More...

void	__WFE (void)
	Wait For Event. More...

void	__SEV (void)
	Send Event. More...

void	__BKPT (uint8_t value)
	Set Breakpoint. More...

void	__ISB (void)
	Instruction Synchronization Barrier. More...

void	__DSB (void)
	Data Synchronization Barrier. More...

void	__DMB (void)
	Data Memory Barrier. More...

uint32_t	__REV (uint32_t value)
	Reverse byte order (32 bit) More...

uint32_t	__REV16 (uint32_t value)
	Reverse byte order (16 bit) More...

int32_t	__REVSH (int32_t value)
	Reverse byte order in signed short value. More...

uint32_t	__RBIT (uint32_t value)
	Reverse bit order of value [not for Cortex-M0 variants]. More...

uint32_t	__ROR (uint32_t value, uint32_t shift)
	Rotate a value right by a number of bits. More...

uint8_t	__LDREXB (volatile uint8_t *addr)
	LDR Exclusive (8 bit) [not for Cortex-M0 variants]. More...

uint16_t	__LDREXH (volatile uint16_t *addr)
	LDR Exclusive (16 bit) [not for Cortex-M0 variants]. More...

uint32_t	__LDREXW (volatile uint32_t *addr)
	LDR Exclusive (32 bit) [not for Cortex-M0 variants]. More...

uint32_t	__STREXB (uint8_t value, volatile uint8_t *addr)
	STR Exclusive (8 bit) [not for Cortex-M0 variants]. More...

uint32_t	__STREXH (uint16_t value, volatile uint16_t *addr)
	STR Exclusive (16 bit) [not for Cortex-M0 variants]. More...

uint32_t	__STREXW (uint32_t value, volatile uint32_t *addr)
	STR Exclusive (32 bit) [not for Cortex-M0 variants]. More...

void	__CLREX (void)
	Remove the exclusive lock [not for Cortex-M0 variants]. More...

uint32_t	__SSAT (unint32_t value, uint32_t sat)
	Signed Saturate [not for Cortex-M0 variants]. More...

uint32_t	__USAT (uint32_t value, uint32_t sat)
	Unsigned Saturate [not for Cortex-M0 variants]. More...

uint8_t	__CLZ (uint32_t value)
	Count leading zeros [not for Cortex-M0 variants]. More...

Description

The following functions generate specific Cortex-M instructions that cannot be directly accessed by the C/C++ Compiler.

Function Documentation

void __BKPT ( uint8_t value )

This function causes the processor to enter Debug state. Debug tools can use this to investigate system state when the instruction at a particular address is reached.

Parameters

[in] value is ignored by the processor. If required, a debugger can use it to obtain additional information about the breakpoint.

void __CLREX ( void )

This function removes the exclusive lock which is created by LDREX [not for Cortex-M0 variants].

uint8_t __CLZ ( uint32_t value )

This function counts the number of leading zeros of a data value [not for Cortex-M0 variants].

Parameters

[in] value Value to count the leading zeros

Returns: number of leading zeros in value

void __DMB ( void )

This function ensures the apparent order of the explicit memory operations before and after the instruction, without ensuring their completion.

void __DSB ( void )

This function acts as a special kind of Data Memory Barrier. It completes when all explicit memory accesses before this instruction complete.

void __ISB ( void )

Instruction Synchronization Barrier flushes the pipeline in the processor, so that all instructions following the ISB are fetched from cache or memory, after the instruction has been completed.

uint8_t __LDREXB ( volatile uint8_t * addr )

This function performs a exclusive LDR command for 8 bit value [not for Cortex-M0 variants].

Parameters

[in] *addr Pointer to data

Returns: value of type uint8_t at (*addr)

uint16_t __LDREXH ( volatile uint16_t * addr )

This function performs a exclusive LDR command for 16 bit values [not for Cortex-M0 variants].

Parameters

[in] *addr Pointer to data

Returns: value of type uint16_t at (*addr)

uint32_t __LDREXW ( volatile uint32_t * addr )

This function performs a exclusive LDR command for 32 bit values [not for Cortex-M0 variants].

Parameters

[in] *addr Pointer to data

Returns: value of type uint32_t at (*addr)

void __NOP ( void )

This function does nothing. This instruction can be used for code alignment purposes.

uint32_t __RBIT ( uint32_t value )

This function reverses the bit order of the given value [not for Cortex-M0 variants].

Parameters

[in] value Value to reverse

Returns: Reversed value

uint32_t __REV ( uint32_t value )

This function reverses the byte order in integer value.

Parameters

[in] value Value to reverse

Returns: Reversed value

uint32_t __REV16 ( uint32_t value )

This function reverses the byte order in two unsigned short values.

Parameters

[in] value Value to reverse

Returns: Reversed value

Note: The function can be disabled by defining the compile time flag __NO_EMBEDDED_ASM. This rule applies to the ARM toolchain. For example:
#ifndef __NO_EMBEDDED_ASM

__REV16(0x1);

#endif

int32_t __REVSH ( int32_t value )

This function reverses the byte order in a signed short value with sign extension to integer.

Parameters

[in] value Value to reverse

Returns: Reversed value

Note: The function can be disabled by defining the compile time flag __NO_EMBEDDED_ASM. This rule applies to the ARM toolchain. For example:
#ifndef __NO_EMBEDDED_ASM

__REVSH(0x1);

#endif

uint32_t __ROR	(	uint32_t	value,
		uint32_t	shift
	)

This function rotates a value right by a specified number of bits.

Parameters

[in]	value	Value to be shifted right
[in]	shift	Number of bits in the range [1..31]

Returns: Rotated value

void __SEV ( void )

Send Event is a hint instruction. It causes an event to be signaled to the CPU.

uint32_t __SSAT	(	unint32_t	value,
		uint32_t	sat
	)

This function saturates a signed value [not for Cortex-M0 variants].

Parameters

[in]	value	Value to be saturated
[in]	sat	Bit position to saturate to [1..32]

Returns: Saturated value

uint32_t __STREXB	(	uint8_t	value,
		volatile uint8_t *	addr
	)

This function performs a exclusive STR command for 8 bit values [not for Cortex-M0 variants].

Parameters

[in]	value	Value to store
[in]	*addr	Pointer to location

Returns: 0 Function succeeded; 1 Function failed

uint32_t __STREXH	(	uint16_t	value,
		volatile uint16_t *	addr
	)

This function performs a exclusive STR command for 16 bit values [not for Cortex-M0 variants].

Parameters

[in]	value	Value to store
[in]	*addr	Pointer to location

Returns: 0 Function succeeded; 1 Function failed

uint32_t __STREXW	(	uint32_t	value,
		volatile uint32_t *	addr
	)

This function performs a exclusive STR command for 32 bit values [not for Cortex-M0 variants].

Parameters

[in]	value	Value to store
[in]	*addr	Pointer to location

Returns: 0 Function succeeded; 1 Function failed

uint32_t __USAT	(	uint32_t	value,
		uint32_t	sat
	)

This function saturates an unsigned value [not for Cortex-M0 variants].

Parameters

[in]	value	Value to be saturated
[in]	sat	Bit position to saturate to [0..31]

Returns: Saturated value

void __WFE ( void )

Wait For Event is a hint instruction that permits the processor to enter a low-power state until an events occurs:

If the event register is 0, then WFE suspends execution until one of the following events occurs:
- An exception, unless masked by the exception mask registers or the current priority level.
- An exception enters the Pending state, if SEVONPEND in the System Control Register is set.
- A Debug Entry request, if Debug is enabled.
- An event signaled by a peripheral or another processor in a multiprocessor system using the SEV instruction.

If the event register is 1, then WFE clears it to 0 and returns immediately.

void __WFI ( void )

WFI is a hint instruction that suspends execution until one of the following events occurs:

A non-masked interrupt occurs and is taken.
An interrupt masked by PRIMASK becomes pending.
A Debug Entry request.

Functions

Description

Function Documentation