ARM assembly instruction DCD

ARM assembly instruction DCD

Introduction

DCD: Data Definition pseudo-instruction is
generally used to allocate storage units for specific data and at the same time complete the initialization of allocated storage units.

Syntax format:

标号 DCD（或 DCDU） 表达式

The DCD (or DCDU) pseudo-instruction is used to allocate a continuous word storage unit and initialize it with a specified expression. The expression can be a program label or a numeric expression. DCD can also be replaced by "&".

The word storage unit allocated by DCD is word aligned, while the word storage unit allocated by DCDU is not strictly word aligned.

Example (STM32 startup file):

__Vectors       DCD     __initial_sp               ; Top of Stack
                DCD     Reset_Handler              ; Reset Handler
                DCD     NMI_Handler                ; NMI Handler
                DCD     HardFault_Handler          ; Hard Fault Handler
                DCD     MemManage_Handler          ; MPU Fault Handler
                DCD     BusFault_Handler           ; Bus Fault Handler
                DCD     UsageFault_Handler         ; Usage Fault Handler
                DCD     0                          ; Reserved
                DCD     0                          ; Reserved
                DCD     0                          ; Reserved
                DCD     0                          ; Reserved
                DCD     SVC_Handler                ; SVCall Handler
                DCD     DebugMon_Handler           ; Debug Monitor Handler
                DCD     0                          ; Reserved
                DCD     PendSV_Handler             ; PendSV Handler
                DCD     SysTick_Handler            ; SysTick Handler