Memory

Directives

REQUIRE8

specifies that the current file requires 8-byte alignment of the stack

### PRESERVE8 specifies that the current file preserves 8-byte alignment of the stack

THUMB

  • Provides 16 Bit instruction set
  • fetches instructions by 2 bytes

### ARM

  • Provides 32 bit instruction set
  • Fetches instructions by 4 bytes

DCB (1 byte)

Allocates one or more bytes of memory, and defines the initial runtime contents of the memory

DCD (4 bytes)

Allocates one or more words of memory, aligned on 4-byte boundaries, and defines the initial runtime contents of the memory.

DCW (2 bytes)

Allocates one or more halfwords of memory, aligned on 2-byte boundaries, and defines the initial runtime contents of the memory

### SPACE (1 byte)

store_table             SPACE   16 ; reserves 16 byte

AREA Instruction

The AREA directive instructs the assembler to assemble a new code or data area. Areas are independent, named, indivisible chunks of code or data that are manipulated by the linker. 

    AREA name{,attr}{,attr}...

Arm Reference

Code

    AREA myCode, CODE, READONLY

Variables

    AREA myAsmVar, DATA, READWRITE

    ; VARIABLES

    ALIGN