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[SOLVED] whats mean export in startup arm microcontroller?

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stackprogramer

stackprogramer

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hi,in start up stm32f10x micro what means export?
Code: 
                 EXPORT  __initial_sp
                 EXPORT  __heap_base
                 EXPORT  __heap_limit
whats mean DCD in it?too
Code: 
 DCD     TIM1_CC_IRQHandler         ; TIM1 Capture Compare
                DCD     TIM2_IRQHandler            ; TIM2
                DCD     TIM3_IRQHandler            ; TIM3
                DCD     TIM4_IRQHandler            ; TIM4
                DCD     I2C1_EV_IRQHandler
 

hi,my friend finally i find resource for this tip question,
it is define DCD:
DCD inserts up to three bytes of padding before the first defined word, if necessary, to achieve four-byte alignment.

Use DCDU if you do not require alignment.
Show/hideExamples

data1 DCD 1,5,20 ; Defines 3 words containing
; decimal values 1, 5, and 20
data2 DCD mem06 + 4 ; Defines 1 word containing 4 +
; the address of the label mem06
AREA MyData, DATA, READWRITE
DCB 255 ; Now misaligned ...
data3 DCDU 1,5,20 ; Defines 3 words containing
; 1, 5 and 20, not word aligned
Click to expand...
for more swim in this ocean see these links:i like them very much:
http://www.keil.com/support/man/docs/armasm/armasm_dom1361290005934.htm
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0489c/Babbfcga.html
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.home/index.html

http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0041c/Babbfcga.html
goodluck:razz:
 

hi...

let me clear this up:
when we do programming, we write them either in assembly or c language.at the first stage the Labels of one file is unrecognized for the other files. and when we compile it, consider the case that a function is in one file, and the defenition for it is in the another file. so we use EXPORT/IMPORT to access the different labels in different files.

in your example EXPORT __initial_sp :allow the other files in your project to access that label.
 
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