Intrinsic Functions for CPU Instructions

Functions that generate specific Cortex-M CPU Instructions. More...

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 (16 bit) More...
uint32_t	__RBIT (uint32_t value)
	Reverse bit order of value. 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, Cortex-M0+, or SC000]. More...
uint16_t	__LDREXH (volatile uint16_t *addr)
	LDR Exclusive (16 bit) [not for Cortex-M0, Cortex-M0+, or SC000]. More...
uint32_t	__LDREXW (volatile uint32_t *addr)
	LDR Exclusive (32 bit) [not for Cortex-M0, Cortex-M0+, or SC000]. More...
uint32_t	__STREXB (uint8_t value, volatile uint8_t *addr)
	STR Exclusive (8 bit) [not for Cortex-M0, Cortex-M0+, or SC000]. More...
uint32_t	__STREXH (uint16_t value, volatile uint16_t *addr)
	STR Exclusive (16 bit) [not for Cortex-M0, Cortex-M0+, or SC000]. More...
uint32_t	__STREXW (uint32_t value, volatile uint32_t *addr)
	STR Exclusive (32 bit) [not for Cortex-M0, Cortex-M0+, or SC000]. More...
void	__CLREX (void)
	Remove the exclusive lock [not for Cortex-M0, Cortex-M0+, or SC000]. More...
int32_t	__SSAT (int32_t value, uint32_t sat)
	Signed Saturate [not for Cortex-M0, Cortex-M0+, or SC000]. More...
uint32_t	__USAT (uint32_t value, uint32_t sat)
	Unsigned Saturate [not for Cortex-M0, Cortex-M0+, or SC000]. More...
uint8_t	__CLZ (uint32_t value)
	Count leading zeros. More...
uint32_t	__RRX (uint32_t value)
	Rotate Right with Extend (32 bit) More...
uint8_t	__LDRBT (uint8_t ptr)
	LDRT Unprivileged (8 bit) More...
uint16_t	__LDRHT (uint16_t ptr)
	LDRT Unprivileged (16 bit) More...
uint32_t	__LDRT (uint32_t ptr)
	LDRT Unprivileged (32 bit) More...
void	__STRBT (uint8_t value, uint8_t ptr)
	STRT Unprivileged (8 bit) More...
void	__STRHT (uint16_t value, uint16_t ptr)
	STRT Unprivileged (16 bit) More...
void	__STRT (uint32_t value, uint32_t ptr)
	STRT Unprivileged (32 bit) More...
uint8_t	__LDAB (volatile uint8_t *ptr)
	Load-Acquire (8 bit) More...
uint16_t	__LDAH (volatile uint16_t *ptr)
	Load-Acquire (16 bit) More...
uint32_t	__LDA (volatile uint32_t *ptr)
	Load-Acquire (32 bit) More...
void	__STLB (uint8_t value, volatile uint8_t *ptr)
	Store-Release (8 bit) More...
void	__STLH (uint16_t value, volatile uint16_t *ptr)
	Store-Release (16 bit) More...
void	__STL (uint32_t value, volatile uint32_t *ptr)
	Store-Release (32 bit) More...
uint8_t	__LDAEXB (volatile uint32_t *ptr)
	Load-Acquire Exclusive (8 bit) More...
uint16_t	__LDAEXH (volatile uint32_t *ptr)
	Load-Acquire Exclusive (16 bit) More...
uint32_t	__LDAEX (volatile uint32_t *ptr)
	Load-Acquire Exclusive (32 bit) More...
uint32_t	__STLEXB (uint8_t value, volatile uint8_t *ptr)
	Store-Release Exclusive (8 bit) More...
uint32_t	__STLEXH (uint16_t value, volatile uint16_t *ptr)
	Store-Release Exclusive (16 bit) More...
uint32_t	__STLEX (uint32_t value, volatile uint32_t *ptr)
	Store-Release Exclusive (32 bit) More...

Description

The following functions generate specific Cortex-M instructions that cannot be directly accessed by the C/C++ Compiler. Refer to the Cortex-M Reference Manuals for detailed information about these Cortex-M instructions.

Note

When using the Arm Compiler Toolchain the following Intrinsic Functions for CPU Instructions are implemented using the Embedded Assembler: __RRX, <Bruno: add more...>. The usage of the Embedded Assembler can be disabled by with define __NO_EMBEDDED_ASM. This avoids potential side effects of the Embedded Assembler. Refer to Compiler User Guide - Using the Inline and Embedded Assemblers of the Arm Compiler for more information.

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, Cortex-M0+, or SC000].

uint8_t __CLZ

(

uint32_t

value

)

This function counts the number of leading zeros of a data value.

On Armv6-M (Cortex-M0, Cortex-M0+, and SC000) this function is not available as a core instruction instruction and thus __CLZ is implemented in software.

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.

uint32_t __LDA

(

volatile uint32_t *

ptr

)

Executes a LDA instruction for 32 bit values.

Parameters

[in]

ptr

Pointer to data

Returns

value of type uint32_t at (*ptr)

Note

Only availabe for Armv8-M Architecture.

uint8_t __LDAB

(

volatile uint8_t *

ptr

)

Executes a LDAB instruction for 8 bit value.

Parameters

[in]

ptr

Pointer to data

Returns

value of type uint8_t at (*ptr)

Note

Only availabe for Armv8-M Architecture.

uint32_t __LDAEX

(

volatile uint32_t *

ptr

)

Executes a LDA exclusive instruction for 32 bit values.

Parameters

[in]

ptr

Pointer to data

Returns

value of type uint32_t at (*ptr)

Note

Only availabe for Armv8-M Architecture.

uint8_t __LDAEXB

(

volatile uint32_t *

ptr

)

Executes a LDAB exclusive instruction for 8 bit value.

Parameters

[in]

ptr

Pointer to data

Returns

value of type uint8_t at (*ptr)

Note

Only availabe for Armv8-M Architecture.

uint16_t __LDAEXH

(

volatile uint32_t *

ptr

)

Executes a LDAH exclusive instruction for 16 bit values.

Parameters

[in]

ptr

Pointer to data

Returns

value of type uint16_t at (*ptr)

Note

Only availabe for Armv8-M Architecture.

uint16_t __LDAH

(

volatile uint16_t *

ptr

)

Executes a LDAH instruction for 16 bit values.

Parameters

[in]

ptr

Pointer to data

Returns

value of type uint16_t at (*ptr)

Note

Only availabe for Armv8-M Architecture.

uint8_t __LDRBT

(

uint8_t

ptr

)

This function executed an Unprivileged LDRT command for 8 bit value.

Parameters

[in]

ptr

Pointer to data

Returns

value of type uint8_t at (*ptr)

uint8_t __LDREXB

(

volatile uint8_t *

addr

)

This function executed an exclusive LDR command for 8 bit value [not for Cortex-M0, Cortex-M0+, or SC000].

Parameters

[in]

*addr

Pointer to data

Returns

value of type uint8_t at (*addr)

uint16_t __LDREXH

(

volatile uint16_t *

addr

)

This function executed an exclusive LDR command for 16 bit values [not for Cortex-M0, Cortex-M0+, or SC000].

Parameters

[in]

*addr

Pointer to data

Returns

value of type uint16_t at (*addr)

uint32_t __LDREXW

(

volatile uint32_t *

addr

)

This function executed an exclusive LDR command for 32 bit values [not for Cortex-M0, Cortex-M0+, or SC000].

Parameters

[in]

*addr

Pointer to data

Returns

value of type uint32_t at (*addr)

uint16_t __LDRHT

(

uint16_t

ptr

)

This function executed an Unprivileged LDRT command for 16 bit values.

Parameters

[in]

ptr

Pointer to data

Returns

value of type uint16_t at (*ptr)

uint32_t __LDRT

(

uint32_t

ptr

)

This function executed an Unprivileged LDRT command for 32 bit values.

Parameters

[in]

ptr

Pointer to data

Returns

value of type uint32_t at (*ptr)

void __NOP

(

void

)

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

uint32_t __RBIT

(

uint32_t

value

)

Parameters

[in]

value

Value to reverse

Returns

Reversed value

uint32_t __REV

(

uint32_t

value

)

Reverses the byte order in unsigned integer value. For example, 0x12345678 becomes 0x78563412.

Parameters

[in]

value

Value to reverse

Returns

Reversed value

uint32_t __REV16

(

uint32_t

value

)

Reverses the byte order within each halfword of a word. For example, 0x12345678 becomes 0x34127856.

Parameters

[in]

value

Value to reverse

Returns

Reversed value

int32_t __REVSH

(

int32_t

value

)

Reverses the byte order in a 16-bit value and returns the signed 16-bit result. For example, 0x0080 becomes 0x8000.

Parameters

[in]

value

Value to reverse

Returns

Reversed value

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

uint32_t __RRX

(

uint32_t

value

)

This function moves each bit of a bitstring right by one bit. The carry input is shifted in at the left end of the bitstring.

Parameters

[in]

value

Value to rotate

Returns

Rotated value

void __SEV

(

void

)

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

int32_t __SSAT	(	int32_t	value,
		uint32_t	sat
	)

This function saturates a signed value [not for Cortex-M0, Cortex-M0+, or SC000].

Parameters

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

Returns

Saturated value

void __STL	(	uint32_t	value,
		volatile uint32_t *	ptr
	)

Executes a STL instruction for 32 bit values.

Parameters

[in]	value	Value to store
[in]	ptr	Pointer to location

Note

Only availabe for Armv8-M Architecture.

void __STLB	(	uint8_t	value,
		volatile uint8_t *	ptr
	)

Executes a STLB instruction for 8 bit values.

Parameters

[in]	value	Value to store
[in]	ptr	Pointer to location

Note

Only availabe for Armv8-M Architecture.

uint32_t __STLEX	(	uint32_t	value,
		volatile uint32_t *	ptr
	)

Executes a STL exclusive instruction for 32 bit values.

Parameters

[in]	value	Value to store
[in]	ptr	Pointer to location

Returns

0 Function succeeded

1 Function failed

Note

Only availabe for Armv8-M Architecture.

uint32_t __STLEXB	(	uint8_t	value,
		volatile uint8_t *	ptr
	)

Executes a STLB exclusive instruction for 8 bit values.

Parameters

[in]	value	Value to store
[in]	ptr	Pointer to location

Returns

0 Function succeeded

1 Function failed

Note

Only availabe for Armv8-M Architecture.

uint32_t __STLEXH	(	uint16_t	value,
		volatile uint16_t *	ptr
	)

Executes a STLH exclusive instruction for 16 bit values.

Parameters

[in]	value	Value to store
[in]	ptr	Pointer to location

Returns

0 Function succeeded

1 Function failed

Note

Only availabe for Armv8-M Architecture.

void __STLH	(	uint16_t	value,
		volatile uint16_t *	ptr
	)

Executes a STLH instruction for 16 bit values.

Parameters

[in]	value	Value to store
[in]	ptr	Pointer to location

Note

Only availabe for Armv8-M Architecture.

void __STRBT	(	uint8_t	value,
		uint8_t	ptr
	)

This function executed an Unprivileged STRT command for 8 bit values.

Parameters

[in]	value	Value to store
[in]	ptr	Pointer to location

uint32_t __STREXB	(	uint8_t	value,
		volatile uint8_t *	addr
	)

This function executed an exclusive STR command for 8 bit values [not for Cortex-M0, Cortex-M0+, or SC000].

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 executed an exclusive STR command for 16 bit values [not for Cortex-M0, Cortex-M0+, or SC000].

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 executed an exclusive STR command for 32 bit values [not for Cortex-M0, Cortex-M0+, or SC000].

Parameters

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

Returns

0 Function succeeded

1 Function failed

void __STRHT	(	uint16_t	value,
		uint16_t	ptr
	)

This function executed an Unprivileged STRT command for 16 bit values.

Parameters

[in]	value	Value to store
[in]	ptr	Pointer to location

void __STRT	(	uint32_t	value,
		uint32_t	ptr
	)

This function executed an Unprivileged STRT command for 32 bit values.

Parameters

[in]	value	Value to store
[in]	ptr	Pointer to location

uint32_t __USAT	(	uint32_t	value,
		uint32_t	sat
	)

This function saturates an unsigned value [not for Cortex-M0, Cortex-M0+, or SC000].

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.