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ARM: Help with instruction ADD with Operand2

Craig Webster

Hi,

New to ARM and I don't understand why following doesn't work.

Using Cortex-M3,uVision I get the error 'Expecting constant expression'

ADD R1,R2,R3,ASR R4

All instruction references I can find give the form 'ADD Rd,Rn, <Operand2>'
and listed under 'Operand2' is 'Rm LSL Rs' so the 'ASR R4' should be legal.

Any help to clear this up would be appreciated.

Thanks

Parents
  • 0

    Cortex-M3: ARMv7-M Architecture with Thumb-2 ISA

    Assembler Syntax for ADD instruction:

    ADD{S}<c><q> {<Rd>,} <Rn>, <Rm> {,<shift>}

<c>      Condition
<q>      Qualifier
<Rd>     Destination register
<Rn>     Register that contains the first operand.
<Rm>     Register  that is optionally shifted and used as the second operand
<shift>  Optional shift applied to value read from <Rm>:
         LSL #<n> | LSR #<n> | ASR #<n> | ROR #<n> | RRX

    Example:

    ADD R1,R2,R3,ASR #4

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  • 0

    Cortex-M3: ARMv7-M Architecture with Thumb-2 ISA

    Assembler Syntax for ADD instruction:

    ADD{S}<c><q> {<Rd>,} <Rn>, <Rm> {,<shift>}

<c>      Condition
<q>      Qualifier
<Rd>     Destination register
<Rn>     Register that contains the first operand.
<Rm>     Register  that is optionally shifted and used as the second operand
<shift>  Optional shift applied to value read from <Rm>:
         LSL #<n> | LSR #<n> | ASR #<n> | ROR #<n> | RRX

    Example:

    ADD R1,R2,R3,ASR #4

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