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Arm Compiler armasm User Guide : DCI


The DCI directive allocates memory that is aligned and defines the initial runtime contents of the memory.

In A32 code, it allocates one or more words of memory, aligned on four-byte boundaries.

In T32 code, it allocates one or more halfwords of memory, aligned on two-byte boundaries.


{label} DCI{.W} expr{,expr}


is a numeric expression.
if present, indicates that four bytes must be inserted in T32 code.


The DCI directive is very like the DCD or DCW directives, but the location is marked as code instead of data. Use DCI when writing macros for new instructions not supported by the version of the assembler you are using.

In A32 code, DCI inserts up to three bytes of padding before the first defined word, if necessary, to achieve four-byte alignment. In T32 code, DCI inserts an initial byte of padding, if necessary, to achieve two-byte alignment.

You can use DCI to insert a bit pattern into the instruction stream. For example, use:

DCI 0x46c0

to insert the T32 operation MOV r8,r8.

Example macro

    MACRO           ; this macro translates newinstr Rd,Rm
                    ; to the appropriate machine code
    newinst     $Rd,$Rm
    DCI         0xe16f0f10 :OR: ($Rd:SHL:12) :OR: $Rm

32-bit T32 example

    DCI.W   0xf3af8000   ; inserts 32-bit NOP, 2-byte aligned.