Cortex-M0指令集

处理器使用的是ARMv6-M Thumb指令集，包括大量的32位的使用Thumb-2技术的指令。表7-22列出了Cortex-M0指令和它们的周期数。周期计数以零等待状态的系统为基准。

表7-22  Cortex-M0指令和它们的周期数

操    作

描    述

汇 编 指 令

周    期

MOVE

8-bit immediate

MOVS Rd,#<imm>

     1

Lo to Lo

MOVS Rd,Rm

     1

Any to Any

MOV Rd,Rm

     1

Any to PC

MOV PC,Rm

     3

Add

3-bit immediate

ADDS Rd,Rn,#<imm>

     1

All registers Lo

ADDS Rd,Rn,Rm

     1

续表

操    作

描    述

汇 编 指 令

周    期

 

Any to Any

ADD Rd,Rd,Rm

     1

Any to PC

ADD PC,PC,Rm

     3

8-bit immediate

ADDS Rd,Rd,#<imm>

     1

With carry

ADCS Rd,Rd,Rm

     1

Immediate to SP

ADD SP,SP,#<imm>

     1

Form address from SP

ADD Rd,SP ,#<imm>

     1

Form address from PC

ADR Rd,<label>

     1

Subtract

Lo to Lo

SUBS Rd,Rn,Rm

     1

3-bit immediate

SUBS Rd,Rn,#<imm>

     1

8-bit immediate

SUBS Rd,Rd,#<imm>

     1

 

With carry

SBCS Rd,Rd,Rm

     1

Immediate from SP

SUB SP,SP,#<imm>

     1

Negate

RSBS Rd,Rn,#0

     1

Multiply

Multiply

MULS Rd,Rm,Rd

1或32

Compare

Compare

CMP Rn,Rm

     1

Negative

CMP Rn,Rm

     1

Immediate

CMP Rn,#<imm>

     1

Logical

AND

ANDS Rd, Rd, Rm

     1

Exclusive OR

EORS Rd, Rd, Rm

     1

OR

ORRS Rd, Rd, Rm

     1

Bit clear

BICS Rd, Rd, Rm

     1

Move NOT

MVNS Rd, Rm

     1

AND test

TST Rn, Rm 

     1

Shift

Logical shift left by immediate

LSLS Rd, Rm, #<shift>

     1

Logical shift left by register

LSLS Rd, Rd, Rs

     1

Logical shift right by immediate

LSRS Rd, Rm, #<shift>

     1

Logical shift right by register

LSRS Rd, Rd, Rs

     1

Arithmetic shift right

ASRS Rd, Rm, #<shift>

     1

Arithmetic shift right by register

ASRS Rd, Rd, Rs

     1

Rotate

Rotate right by register

RORS Rd, Rd, Rs

     1

Load

Word, immediate offset

LDR Rd, [Rn, #<imm>]

     2

Halfword, immediate offset

LDRH Rd, [Rn, #<imm>]

     2

Byte, immediate offset

LDRB Rd, [Rn, #<imm>]

     2

Word, register offset

LDR Rd, [Rn, Rm]

     2

续表

操    作

描    述

汇 编 指 令

周    期

 

Halfword, register offset

LDRH Rd, [Rn, Rm]

     2

Signed halfword, register offset

LDRSH Rd, [Rn, Rm]

     2

Byte, register offset

LDRB Rd, [Rn, Rm]

     2

Signed byte, register offset

LDRSB Rd, [Rn, Rm]

     2

PC-relative

LDR Rd, <label>

     2

SP-relative 

LDR Rd, [SP, #<imm>]

     2

Multiple, excluding base

LDM Rn!, {<loreglist>}

   1+N

Multiple, including base

LDM Rn, {<loreglist>}

   1+N

Store

Word, immediate offset

STR Rd, [Rn, #<imm>]

     2

Halfword, immediate offset

STRH Rd, [Rn, #<imm>]

     2

Byte, immediate offset

STRB Rd, [Rn, #<imm>]

     2

Word, register offset

STR Rd, [Rn, Rm]

     2

 

Halfword, register offset

STRH Rd, [Rn, Rm]

     2

Byte, register offset

STRB Rd, [Rn, Rm]

     2

SP-relative

STR Rd, [SP, #<imm>]

     2

Multiple

STM Rn!, {<loreglist>}

   1+N

Push

Push

PUSH {<loreglist>}

   1+N

Push with link register

PUSH {<loreglist>, LR}

   1+N

Pop

Pop

POP {<loreglist>}

   1+N

Pop and return

POP {<loreglist>, PC}

   4+N

Branch

Conditional

B<cc> <label>

   1或3

Unconditional

B<label>

    3

With link

BL<label>

    4

With exchange

BX Rm

    3

With link and exchange

BLX Rm

    3

Extend

Signed halfword to word

SXTH Rd, Rm

    1

Signed byte to word

SXTB Rd, Rm

    1

Unsigned halfword

UXTH Rd, Rm

    1

Unsigned byte

UXTB Rd, Rm

    1

Reverse

Bytes in word

REV Rd, Rm

    1

Bytes in both halfwords

REV16 Rd, Rm

    1

Signed bottom half word

REVSH Rd, Rm

    1

State change

Supervisor Call

SVC #<imm>

    -

Disable interrupts

CPSID i

    1

操    作

描    述

汇 编 指 令

周    期

 

Enable interrupts

CPSIE i

    1

Read special register

MRS Rd, <specreg>

    4

Write special register

MSR <specreg>, Rn

    4

Breakpoint

BKPT #<imm>

    —

Hint

Send event

SEV

    1

Wait for event

WFE

    2

Wait for interrupt

WFI

    2

Yield

YIELD

    1

Hint

No operation

NOP

    1

Barriers

Instruction synchronization

ISB

    4

Data memory

DMB

    4

Data synchronization

DSB

    4

ISO/IEC的C代码不能直接地获取一些Cortex-M0的指令。表7-23列举了CMSIS的C编译器中提供的部分内部函数用于产生这些指令。如果一个C编译器不支持恰当的内部函数，则需要用内嵌汇编来获取有关指令。

表7-23  CMSIS内部函数

指    令

CMSIS内部函数

指   令

CMSIS内部函数

CPSIE i

void __enable_irq(void)

REV

uint32_t __REV(uint32_t int value)

CPSID i

void __disable_irq(void)

REV16

uint32_t __REV16(uint32_t int value)

ISB

void __ISB(void)

REVSH

uint32_t __REVSH(uint32_t int value)

DSB

void __DSB(void)

SEV

void __SEV(void)

DMB

void __DMB(void)

WFE

void __WFE(void)

NOP

void __NOP(void)

WFI

void __WFI(void)

CMSIS也提供了几个函数用于获取特殊的寄存器，如表7-24所示。

表7-24  CMSIS提供的用于获取特殊寄存器的函数

特殊寄存器

获 取 方 式

CMSIS函数

PRIMASK

读

uint32_t __get_PRIMASK(void)

写

void __set_PRIMASK(void)

CONTROL

读

Uint32_t __get_CONTROL(uint32_t value)

写

Void __set_CONTROL(uint32_t value)

MSP

读

Uint32_t __get_MSP(void)

写

Void __set_MSP(uint32_t TopOfMainStack)

PSP

读

Uint32_t __get_PSP(void)

写

Void __set_PSP(uint32_t TopOfMainStack)