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ChristopherNeufelt

Senior Boarder

2008/10/29 05:11

Simple assembly programming error

Hello

The topic that I raise has to deal with assembly programming, in particular writing everything with assembler and flashing to a development board. In my case the LM3S1968 (I call it flower power for obvious reasons;)
The environment that I have is Keil Uvision3 and I use the DOS assembler located in bin31.

The code, property of J.Yiu is:

StackTop EQU 0x20002000 ; constant for SP starting value
AREA Program, CODE, READONLY ; declare area for code
DCD StackTop ; Stack top
DCD START ; Reset vector
ENTRY

START MOV R0, #10 ; Starting loop counter value
MOV R1, #0 ; starting result
; Calculated 10+9+8+...+1
LOOP ADD R1, R0 ; R1 = R1 + R0
SUBS R0, #1 ; Decrement R0, update flag (“S” suffi x)
BNE LOOP ; If result not zero jump to loop
; Result is now in R1
HERE BAL HERE ; Infinite loop
END

Let the assembler directive in command prompt (DOS) to be:
C:armasm --li --device=DLM -g --list CN1.list CN1.s
and the linker to be:
C:armlink --device=DLM --rw_base 0x20000000 --ro_base 0x0 --entry 0x0 -o CN1.elf CN1.o

Now the beautiful error message: L6236E: No section matches selector -no section to be First/Last.

What all this means? According to "ADS error and warnings" I should add the --entry 0x0 in order to indicate the start of my program which I suppose I did. Any suggestions?

Sincerely
Chris

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tim124

Expert Boarder

2008/10/29 07:37

Re:Simple assembly programming error

if you look at:

http://www.keil.com/forum/docs/thread13259.asp

it also says you need to add:

Code:

 
AREA subrout, CODE, READONLY ENTRY
<span style="color: #FF0000">ENTRY;</span>
...

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cb1

Platinum Boarder

2008/10/29 07:40

Re:Simple assembly programming error

Hi Chris,

Curious why you seek to write everything in Assembler. Is it so that you use free version of IDE - without code-size limitation?

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ChristopherNeufelt

Senior Boarder

2008/10/29 07:59

Re:Simple assembly programming error

Hallo
At Tim124:
I am aware of this thread. It did not work on my code, not even at a complete copy of the code provided.

At cb1:
There is a reason of writing to assembler: understanding preciselly the way the controller works because I evaluate it for safety critical applications: in addition, I have already wrote code in C that needs debugging with the disassembler. To understand some parts of the assembler you need assembler.
The environment that I use are not unlimited:
Keil uVision3 has 32k evaluation capability.
Code Red has expired its date, but in any case was a mess to use.

Love, Happiness and Peace to everybody

Chris

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joseph_yiu

Expert Boarder

2008/10/31 07:01

Re:Simple assembly programming error

Hi there,
Try separating the vector and the program code into two sections:

Code:

 
StackTop EQU 0x20002000 ; constant for SP starting value

    AREA RESET, DATA, READONLY ; declare area for code
    EXPORT  __VECTORS
__VECTORS
    DCD StackTop ; Stack top
    DCD START ; Reset vector

    AREA Program, CODE, READONLY ; declare area for code
    ENTRY
    EXPORT  START
START 
    MOV R0, #10 ; Starting loop counter value
    MOV R1, #0 ; starting result
    ; Calculated 10+9+8+...+1
LOOP 
    ADD R1, R0 ; R1 = R1 + R0
    SUBS R0, #1 ; Decrement R0, update flag (“S” suffi x)
    BNE LOOP ; If result not zero jump to loop
    ; Result is now in R1
HERE 
    BAL HERE ; Infinite loop
    END



And no need to use --entry as the entry point is already indicated in the code. But you need to add --first in linker option:

armasm --li --device=DLM -g --list CN1.list CN1.s

armlink --device=DLM --rw_base 0x20000000 --ro_base 0x0 --first __VECTORS -o CN1.elf CN1.o

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ChristopherNeufelt

Senior Boarder

2008/10/31 07:36

Re:Simple assembly programming error

Hello Mr. Yiu
A great thanks for the personal touch to your code.
The main problem that most of us facing currently are mostly the complexity of the tools accompanied by the complexity of our subjects: These add two uncertainties to our endevour which add up to the development of the software.
I will consider this thread closed- Thanks everyone for your input

Chris

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