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Forum: ARM programming with GCC/GNU tools long long division


Author: Alex Svetek (alessio)
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Hello,

I am trying to use long long division on ARM7 (LPC2103, LPC2129).

I wrote just a small program to test this something like:

int main(void)
{
volatile long long a,b,c;

a = b/c;

return 0;
}


If I try to compile this with the latest CodeSourcery tools 2007Q3,
the process failes with following output:

"-------- begin (mode: ROM_RUN) --------"
arm-none-eabi-gcc (CodeSourcery Sourcery G++ Lite 2007q3-53) 4.2.1
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is
NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.

Compiling C: main.c
c:/tools/DEVEL/CodeSourcery\bin\arm-none-eabi-gcc -c  -mcpu=arm7tdmi
-I. -gdwarf-2 -DROM_RUN  -O1 -ffunction-sections -fdata-sections -Wall
-Wcast-align -Wimplicit  -Wpointer-arith -Wswitch -Wredundant-decls
-Wreturn-type -Wshadow -Wunused -Wa,-adhlns=main.lst  -I./INC
-Wcast-qual -MD -MP -MF .dep/main.o.d -Wnested-externs  -std=gnu99
-Wmissing-prototypes  -Wstrict-prototypes -Wmissing-declarations main.c
-o main.o
ECHO is off.
Linking: main.elf
c:/tools/DEVEL/CodeSourcery\bin\arm-none-eabi-gcc  -mcpu=arm7tdmi  -I.
-gdwarf-2 -DROM_RUN  -O1 -ffunction-sections -fdata-sections -Wall
-Wcast-align -Wimplicit  -Wpointer-arith -Wswitch -Wredundant-decls
-Wreturn-type -Wshadow -Wunused -Wa,-adhlns=startup.lst  -I./INC
-Wcast-qual -MD -MP -MF .dep/main.elf.d startup.o arm_exc.o
low_level_init.o bsp.o isr.o SysTick.o rprintf.o uart.o cmd_parser.o
m_string.o PWM.o debug.o ADC.o MotorDrive.o backup.o iap.o chksum.o
main.o     --output main.elf -nostartfiles
-Wl,-Map=main.map,--cref,--gc-sections   -Tblinky.ld
c:/tools/devel/codesourcery/bin/../lib/gcc/arm-none-eabi/4.2.1\libgcc.a( 
unwind-arm.o):
In function `get_eit_entry':
unwind-arm.c:(.text+0x7a0): undefined reference to `__exidx_start'
unwind-arm.c:(.text+0x7a4): undefined reference to `__exidx_end'
c:/tools/devel/codesourcery/bin/../lib/gcc/arm-none-eabi/4.2.1/../../../ 
../arm-none-eabi/lib\libc.a(lib_a-abort.o):
In function `abort':
abort.c:(.text+0xc): undefined reference to `_exit'
c:/tools/devel/codesourcery/bin/../lib/gcc/arm-none-eabi/4.2.1/../../../ 
../arm-none-eabi/lib\libc.a(lib_a-signalr.o):
In function `_getpid_r':

signalr.c:(.text+0x4): undefined reference to `_getpid'
c:/tools/devel/codesourcery/bin/../lib/gcc/arm-none-eabi/4.2.1/../../../ 
../arm-none-eabi/lib\libc.a(lib_a-signalr.o):
In function `_kill_r':
signalr.c:(.text+0x2c): undefined reference to `_kill'
c:/tools/devel/codesourcery/bin/../lib/gcc/arm-none-eabi/4.2.1/../../../ 
../arm-none-eabi/lib\libc.a(lib_a-sbrkr.o):
In function `_sbrk_r':
sbrkr.c:(.text+0x18): undefined reference to `_sbrk'
collect2: ld returned 1 exit status
cs-make[1]: *** [main.elf] Error 1




If I add to linker scripts following lines:

        /* .ARM.exidx is sorted, so has to go in its own output section.
*/
    .ARM.exidx : {
        __exidx_start = .;
        *(.ARM.exidx* .gnu.linkonce.armexidx.*)
        __exidx_end = .;
    } >ROM


 then the build failes with following output:

"-------- begin (mode: ROM_RUN) --------"
arm-none-eabi-gcc (CodeSourcery Sourcery G++ Lite 2007q3-53) 4.2.1
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is
NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.

ECHO is off.
Linking: main.elf
c:/tools/DEVEL/CodeSourcery\bin\arm-none-eabi-gcc  -mcpu=arm7tdmi  -I.
-gdwarf-2 -DROM_RUN  -O1 -ffunction-sections -fdata-sections -Wall
-Wcast-align -Wimplicit  -Wpointer-arith -Wswitch -Wredundant-decls
-Wreturn-type -Wshadow -Wunused -Wa,-adhlns=startup.lst  -I./INC
-Wcast-qual -MD -MP -MF .dep/main.elf.d startup.o arm_exc.o
low_level_init.o bsp.o isr.o SysTick.o rprintf.o uart.o cmd_parser.o
m_string.o PWM.o debug.o ADC.o MotorDrive.o backup.o iap.o chksum.o
main.o     --output main.elf -nostartfiles
-Wl,-Map=main.map,--cref,--gc-sections   -Tblinky.ld
c:/tools/devel/codesourcery/bin/../lib/gcc/arm-none-eabi/4.2.1/../../../ 
../arm-none-eabi/bin/ld.exe:
main.elf: warning: sh_link not set for section `.ARM.exidx'
c:/tools/devel/codesourcery/bin/../lib/gcc/arm-none-eabi/4.2.1/../../../ 
../arm-none-eabi/lib\libc.a(lib_a-abort.o):
In function `abort':
abort.c:(.text+0xc): undefined reference to `_exit'

c:/tools/devel/codesourcery/bin/../lib/gcc/arm-none-eabi/4.2.1/../../../ 
../arm-none-eabi/lib\libc.a(lib_a-signalr.o):
In function `_getpid_r':
signalr.c:(.text+0x4): undefined reference to `_getpid'
c:/tools/devel/codesourcery/bin/../lib/gcc/arm-none-eabi/4.2.1/../../../ 
../arm-none-eabi/lib\libc.a(lib_a-signalr.o):
In function `_kill_r':
signalr.c:(.text+0x2c): undefined reference to `_kill'
c:/tools/devel/codesourcery/bin/../lib/gcc/arm-none-eabi/4.2.1/../../../ 
../arm-none-eabi/lib\libc.a(lib_a-sbrkr.o):
In function `_sbrk_r':
sbrkr.c:(.text+0x18): undefined reference to `_sbrk'
collect2: ld returned 1 exit status
cs-make[1]: *** [main.elf] Error 1



The same process with latest yagarto tools (arm-elf-gcc version 4.2.2),
and no modifications in linker script, compiles without errors.

I need to use CodeSourcery tools. Does anybody have a clue what am I
missing?

Thank you in advance,
alessio

Author: Clifford Slocombe (clifford)
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It looks like you have not implemented the necessary syscalls. Since the
code makes no library calls you might think that you need not do that,
but long long is not a fundamental machine type on ARM, so the compiler
may insert calls to functions for even basic operations on such a type.

That's my guess in any case; the use of long long and caused 64bit
support code to get linked, and that code includes the calls the linker
says are missing. The syscall stubs are target specific and need to be
implemented by you (or use/adapt one of the existing examples).

Clifford

Author: Alex Svetek (alessio)
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Clifford, thank you for your reply.

I read about necessary syscall stubs in libm manual,
but didn't need them up until now. Can anybody please
give me some link where to start digging about those syscalls?

I am still curious why does the same program compile without errors
with yagarto arm-elf-gcc, but fails with CodeSourcery arm-none-eabi-gcc.
Built program with yagarto needs additional 1kB of space for long long
division and works OK.


The only difference between successful and unsuccessful compilation is
in makefile's COMPILER variable:


COMPILER = elf

ifeq ($(COMPILER),elf)
# GNU-ARM tools directory
GNU_ARM = c:/tools/DEVEL/yagarto

# The gcc compiler and linker
CC      = $(GNU_ARM)\bin\arm-elf-gcc
ASM     = $(GNU_ARM)\bin\arm-elf-as
LINK    = $(GNU_ARM)\bin\arm-elf-gcc
OBJCOPY = $(GNU_ARM)\bin\arm-elf-objcopy
SIZE = $(GNU_ARM)\bin\arm-elf-size
NM = $(GNU_ARM)/bin/arm-elf-nm
OBJDUMP =$(GNU_ARM)/bin/arm-elf-objdump

else

# GNU-ARM tools directory
GNU_ARM = c:/tools/DEVEL/CodeSourcery

# The gcc compiler and linker
CC      = $(GNU_ARM)\bin\arm-none-eabi-gcc
ASM     = $(GNU_ARM)\bin\arm-none-eabi-as
LINK    = $(GNU_ARM)\bin\arm-none-eabi-gcc
OBJCOPY = $(GNU_ARM)\bin\arm-none-eabi-objcopy
SIZE = $(GNU_ARM)\bin\arm-none-eabi-size
NM = $(GNU_ARM)/bin/arm-none-eabi-nm
OBJDUMP =$(GNU_ARM)/bin/arm-none-eabi-objdump
endif


Regards,
alessio

Author: Spencer Oliver (ntfreak)
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> I am still curious why does the same program compile without errors
> with yagarto arm-elf-gcc, but fails with CodeSourcery arm-none-eabi-gcc.
> Built program with yagarto needs additional 1kB of space for long long
> division and works OK.
>

This is because codesourcery build newlib (c library) with
--disable-newlib-supplied-syscalls whereas yagarto builds the default
system calls.

Also yagarto is a arm-elf toolchain, and the codesourcery is a arm-eabi
toolchain.
This syscalls interface did change slightly between the two aswell.

Cheers
Spen

Author: Alex Svetek (alessio)
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Spencer Oliver wrote:

> This is because codesourcery build newlib (c library) with
> --disable-newlib-supplied-syscalls whereas yagarto builds the default
> system calls.
>
> Also yagarto is a arm-elf toolchain, and the codesourcery is a arm-eabi
> toolchain.
> This syscalls interface did change slightly between the two aswell.


Spen, I greatly appreciate your helpful reply.

Can you say few words about what is the difference between arm-elf and
arm-eabi
toolchain? Do you have a link describing this, I have a lot more to
learn.

Cheers

Author: Spencer Oliver (ntfreak)
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>
> Spen, I greatly appreciate your helpful reply.
>
> Can you say few words about what is the difference between arm-elf and
> arm-eabi
> toolchain? Do you have a link describing this, I have a lot more to
> learn.
>
> Cheers

for standalone apps you may notice no difference.
It is really todo with a generic standard among targets/tools.

For example, if you built a library using Realview you should be able to
link it in with gcc source.

Have a look on arm website for lots of other info.

Cheers
Spen

Author: Qduda 12345 (Company: student) (qduda)
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Spencer Oliver wrote:
>[...]
>
> This is because codesourcery build newlib (c library) with
> --disable-newlib-supplied-syscalls whereas yagarto builds the default
> system calls.
>[...]

Sorry for repling on this old post, but i want to say 'Thanks alot!' for 
this clue. Im on this issue for the whole morning.

So as far as i know by now i need to implement the missing marks _sbrk, 
_exit, _getpid and _kill bymyself. I'm pretty sure im not the only one 
with this issue. Is there a implementation i can use for this? google 
dont gives  matches about.
And i wonder if there is no way to just use a newlib with enabled 
syscalls. I could just re-compile (not using installer) the codesourcery 
w/o the disable option and use the built libc.a instead of my current.

I'm thankfull for any clue bout this.

Oh and bytheway im working on a cortex-m1

Author: Clifford Slocombe (clifford)
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Qduda 12345 wrote:
> Spencer Oliver wrote:

> So as far as i know by now i need to implement the missing marks _sbrk,
> _exit, _getpid and _kill bymyself. I'm pretty sure im not the only one
> with this issue. Is there a implementation i can use for this? google
> dont gives  matches about.
Read the "Building Bare-metal ARM with GNU" document in the ARM-GCC 
development resources sticky thread (http://embdev.net/topic/129986)

> And i wonder if there is no way to just use a newlib with enabled
> syscalls. I could just re-compile (not using installer) the codesourcery
> w/o the disable option and use the built libc.a instead of my current.

Many of the syscalls are target/platform specific, which is why they are 
not provided, they are what glue teh library you your specific 
hardware.

In most cases you do not need to implement more than an empty stub, byt 
_sbrk is critical since it enables dynamic memory allocation and heap 
management.

Author: Qduda 12345 (Company: student) (qduda)
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I just implemented all of the missing references as stub function. Its 
working. All i wonder is why my linker wants a reference to _sbrk. I 
dont use functions useing memory allocation. The only "none-basic" 
function is "memcpy" which is part of string.h, and from what i know it 
dont use dynamic memory allocation. Another thing is this _getpid 
mark... no idea why the linker needs it... whatever i implemented stubs 
and its working.
If anyone got the same issue, just try out if simple stub functions are 
working, it won't hurt.

Thanks for advice!

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