PM0214 datasheet(173/245 Pages) STMICROELECTRONICS

173 / 245 page

DocID022708 Rev 4

173/245

PM0214

The STM32 Cortex-M4 instruction set

244

3.11.5

ISB

Instruction synchronization barrier.

Syntax

ISB{cond}

where: ‘cond’ is an optional condition code, see Conditional execution on page 64.

Operation

ISB acts as an instruction synchronization barrier. It flushes the pipeline of the processor, so

that all instructions following the ISB are fetched from cache or memory again, after the ISB

instruction has been completed.

Condition flags

This instruction does not change the flags.

Examples

ISB

; Instruction Synchronisation Barrier

3.11.6

MRS

Move the contents of a special register to a general-purpose register.

Syntax

MRS{cond} Rd, spec_reg

where:

•

‘cond’ is an optional condition code, see Conditional execution on page 64.

•

‘Rd’ is the destination register.

•

‘spec_reg’ can be any of: APSR, IPSR, EPSR, IEPSR, IAPSR, EAPSR, PSR, MSP,

PSP, PRIMASK, BASEPRI, BASEPRI_MAX, FAULTMASK, or CONTROL.

Operation

Use MRS in combination with MSR as part of a read-modify-write sequence for updating a

PSR, for example to clear the Q flag. See MSR on page 174.

In process swap code, the programmers model state of the process being swapped out

must be saved, including relevant PSR contents. Similarly, the state of the process being

swapped in must also be restored. These operations use MRS in the state-saving

instruction sequence and MSR in the state-restoring instruction sequence.

BASEPRI_MAX is an alias of BASEPRI when used with the MRS instruction.

Restrictions

Rd must not be SP and must not be PC.

Condition flags

This instruction does not change the flags.

Examples

PM0214 датащи(PDF) 173 Page - STMicroelectronics

PM0214 датащи(HTML) 173 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL