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Division function

Division function

2004-11-01 by dean_j_greaves

Hi,
  I having a problem with some code i'm developing on the LPC2214 
chip using GNU tools.  
  I have a simple function that performs a division.

  unsigned int a=0, b=1000, c=10;

  a=b/c;

  When i compile up the code and download to the target, the code 
breaks when i step over this division routine.  When i step in to the 
assembly code for the division, it has compiled in  __divsi3 from the 
libgcc library.
  The problem appears to be that just before the return from the 
division function, it attempts to restore registers from the stack 
that it never actually push onto the stack.
  Has anyone ever come across this before.  Any help would be 
gratefully received.

  Dean

Re: [lpc2000] Division function

2004-11-01 by Michael Anburaj

Send the elf file if it's a small piece of code.

-Mike.

--- dean_j_greaves <dgreaves@...> wrote:

> 
> Hi,
>   I having a problem with some code i'm developing
> on the LPC2214 
> chip using GNU tools.  
>   I have a simple function that performs a division.
> 
>   unsigned int a=0, b=1000, c=10;
> 
>   a=b/c;
> 
>   When i compile up the code and download to the
> target, the code 
> breaks when i step over this division routine.  When
> i step in to the 
> assembly code for the division, it has compiled in 
> __divsi3 from the 
> libgcc library.
>   The problem appears to be that just before the
> return from the 
> division function, it attempts to restore registers
> from the stack 
> that it never actually push onto the stack.
>   Has anyone ever come across this before.  Any help
> would be 
> gratefully received.
> 
>   Dean
> 
> 
> 
> 



		
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Re: [lpc2000] Division function

2004-11-01 by Michael Anburaj

I just tried it on my setup.

source:
------

unsigned int test(U32 b, U32 c)
{
	return b/c;
}

void APP_vMain (void)
{
	unsigned int a=0, b=1000, c=0;

	a=test(b,c);

	CONSOL_Printf("a = %d, b = %d, c = %d\n\n",a,b,c);
}

from the elf image:
------------------

40000278 <test>:
40000278:	e1a0c00d 	mov	ip, sp
4000027c:	e92dd800 	stmdb	sp!, {fp, ip, lr, pc}
40000280:	e24cb004 	sub	fp, ip, #4	; 0x4
40000284:	eb000366 	bl	40001024 <__udivsi3>
40000288:	e89da800 	ldmia	sp, {fp, sp, pc}

4000028c <APP_vMain>:
4000028c:	e1a0c00d 	mov	ip, sp
40000290:	e92dd830 	stmdb	sp!, {r4, r5, fp, ip, lr,
pc}
40000294:	e3a05000 	mov	r5, #0	; 0x0
40000298:	e3a04ffa 	mov	r4, #1000	; 0x3e8
4000029c:	e1a01005 	mov	r1, r5
400002a0:	e24cb004 	sub	fp, ip, #4	; 0x4
400002a4:	e1a00004 	mov	r0, r4
400002a8:	ebfffff2 	bl	40000278 <test>
400002ac:	e1a01000 	mov	r1, r0
400002b0:	e59f000c 	ldr	r0, [pc, #12]	; 400002c4
<.text+0x1c4>
400002b4:	e1a02004 	mov	r2, r4
400002b8:	e1a03005 	mov	r3, r5
400002bc:	e89d6830 	ldmia	sp, {r4, r5, fp, sp, lr}
400002c0:	ea000349 	b	40000fec <CONSOL_Printf>
400002c4:	40008efc 	strmid	r8, [r0], -ip


40001024 <__udivsi3>:
40001024:	e2512001 	subs	r2, r1, #1	; 0x1
40001028:	012fff1e 	bxeq	lr
4000102c:	3a000036 	bcc	4000110c <__udivsi3+0xe8>
40001030:	e1500001 	cmp	r0, r1
40001034:	9a000022 	bls	400010c4 <__udivsi3+0xa0>
40001038:	e1110002 	tst	r1, r2
4000103c:	0a000023 	beq	400010d0 <__udivsi3+0xac>
40001040:	e311020e 	tst	r1, #-536870912	; 0xe0000000
40001044:	01a01181 	moveq	r1, r1, lsl #3
40001048:	03a03008 	moveq	r3, #8	; 0x8
4000104c:	13a03001 	movne	r3, #1	; 0x1
40001050:	e3510201 	cmp	r1, #268435456	; 0x10000000
40001054:	31510000 	cmpcc	r1, r0
40001058:	31a01201 	movcc	r1, r1, lsl #4
4000105c:	31a03203 	movcc	r3, r3, lsl #4
40001060:	3afffffa 	bcc	40001050 <__udivsi3+0x2c>
40001064:	e3510102 	cmp	r1, #-2147483648	; 0x80000000
40001068:	31510000 	cmpcc	r1, r0
4000106c:	31a01081 	movcc	r1, r1, lsl #1
40001070:	31a03083 	movcc	r3, r3, lsl #1
40001074:	3afffffa 	bcc	40001064 <__udivsi3+0x40>
40001078:	e3a02000 	mov	r2, #0	; 0x0
4000107c:	e1500001 	cmp	r0, r1
40001080:	20400001 	subcs	r0, r0, r1
40001084:	21822003 	orrcs	r2, r2, r3
40001088:	e15000a1 	cmp	r0, r1, lsr #1
4000108c:	204000a1 	subcs	r0, r0, r1, lsr #1
40001090:	218220a3 	orrcs	r2, r2, r3, lsr #1
40001094:	e1500121 	cmp	r0, r1, lsr #2
40001098:	20400121 	subcs	r0, r0, r1, lsr #2
4000109c:	21822123 	orrcs	r2, r2, r3, lsr #2
400010a0:	e15001a1 	cmp	r0, r1, lsr #3
400010a4:	204001a1 	subcs	r0, r0, r1, lsr #3
400010a8:	218221a3 	orrcs	r2, r2, r3, lsr #3
400010ac:	e3500000 	cmp	r0, #0	; 0x0
400010b0:	11b03223 	movnes	r3, r3, lsr #4
400010b4:	11a01221 	movne	r1, r1, lsr #4
400010b8:	1affffef 	bne	4000107c <__udivsi3+0x58>
400010bc:	e1a00002 	mov	r0, r2
400010c0:	e12fff1e 	bx	lr
400010c4:	03a00001 	moveq	r0, #1	; 0x1
400010c8:	13a00000 	movne	r0, #0	; 0x0
400010cc:	e12fff1e 	bx	lr
400010d0:	e3510801 	cmp	r1, #65536	; 0x10000
400010d4:	21a01821 	movcs	r1, r1, lsr #16
400010d8:	23a02010 	movcs	r2, #16	; 0x10
400010dc:	33a02000 	movcc	r2, #0	; 0x0
400010e0:	e3510c01 	cmp	r1, #256	; 0x100
400010e4:	21a01421 	movcs	r1, r1, lsr #8
400010e8:	22822008 	addcs	r2, r2, #8	; 0x8
400010ec:	e3510010 	cmp	r1, #16	; 0x10
400010f0:	21a01221 	movcs	r1, r1, lsr #4
400010f4:	22822004 	addcs	r2, r2, #4	; 0x4
400010f8:	e3510004 	cmp	r1, #4	; 0x4
400010fc:	82822003 	addhi	r2, r2, #3	; 0x3
40001100:	908220a1 	addls	r2, r2, r1, lsr #1
40001104:	e1a00230 	mov	r0, r0, lsr r2
40001108:	e12fff1e 	bx	lr
4000110c:	e52de004 	str	lr, [sp, #-4]!
40001110:	eb000034 	bl	400011e8 <__div0>
40001114:	e3a00000 	mov	r0, #0	; 0x0
40001118:	e49df004 	ldr	pc, [sp], #4

400011e8 <__div0>:
400011e8:	e12fff1e 	bx	lr


Cheers,
-Mike.



--- dean_j_greaves <dgreaves@...> wrote:

> 
> Hi,
>   I having a problem with some code i'm developing
> on the LPC2214 
> chip using GNU tools.  
>   I have a simple function that performs a division.
> 
>   unsigned int a=0, b=1000, c=10;
> 
>   a=b/c;
> 
>   When i compile up the code and download to the
> target, the code 
> breaks when i step over this division routine.  When
> i step in to the 
> assembly code for the division, it has compiled in 
> __divsi3 from the 
> libgcc library.
>   The problem appears to be that just before the
> return from the 
> division function, it attempts to restore registers
> from the stack 
> that it never actually push onto the stack.
>   Has anyone ever come across this before.  Any help
> would be 
> gratefully received.
> 
>   Dean
> 
> 
> 
> 



		
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RE: [lpc2000] Division function

2004-11-02 by Dean greaves

Hi Michael,

            I wrote a small application this morning with just the divide
routine in it.  When I stepped through the assembly, I noticed that most of
the function is actually missing ???  It does n't look like what you have at
all.  I'm afraid I'm a bit of a rookie at this, I would be grateful for any
help 

 

Please find attached my ELF file

 

 

Cheers and all the best

 Dean

 

 

 

 

 

  _____
Show quoted textHide quoted text
From: Michael Anburaj [mailto:embeddedeng@...] 
Sent: 01 November 2004 17:31
To: lpc2000@yahoogroups.com
Subject: Re: [lpc2000] Division function

 

I just tried it on my setup.

source:
------

unsigned int test(U32 b, U32 c)
{
      return b/c;
}

void APP_vMain (void)
{
      unsigned int a=0, b=1000, c=0;

      a=test(b,c);

      CONSOL_Printf("a = %d, b = %d, c = %d\n\n",a,b,c);
}

from the elf image:
------------------

40000278 <test>:
40000278:      e1a0c00d       mov      ip, sp
4000027c:      e92dd800       stmdb      sp!, {fp, ip, lr, pc}
40000280:      e24cb004       sub      fp, ip, #4      ; 0x4
40000284:      eb000366       bl      40001024 <__udivsi3>
40000288:      e89da800       ldmia      sp, {fp, sp, pc}

4000028c <APP_vMain>:
4000028c:      e1a0c00d       mov      ip, sp
40000290:      e92dd830       stmdb      sp!, {r4, r5, fp, ip, lr,
pc}
40000294:      e3a05000       mov      r5, #0      ; 0x0
40000298:      e3a04ffa       mov      r4, #1000      ; 0x3e8
4000029c:      e1a01005       mov      r1, r5
400002a0:      e24cb004       sub      fp, ip, #4      ; 0x4
400002a4:      e1a00004       mov      r0, r4
400002a8:      ebfffff2       bl      40000278 <test>
400002ac:      e1a01000       mov      r1, r0
400002b0:      e59f000c       ldr      r0, [pc, #12]      ; 400002c4
<.text+0x1c4>
400002b4:      e1a02004       mov      r2, r4
400002b8:      e1a03005       mov      r3, r5
400002bc:      e89d6830       ldmia      sp, {r4, r5, fp, sp, lr}
400002c0:      ea000349       b      40000fec <CONSOL_Printf>
400002c4:      40008efc       strmid      r8, [r0], -ip


40001024 <__udivsi3>:
40001024:      e2512001       subs      r2, r1, #1      ; 0x1
40001028:      012fff1e       bxeq      lr
4000102c:      3a000036       bcc      4000110c <__udivsi3+0xe8>
40001030:      e1500001       cmp      r0, r1
40001034:      9a000022       bls      400010c4 <__udivsi3+0xa0>
40001038:      e1110002       tst      r1, r2
4000103c:      0a000023       beq      400010d0 <__udivsi3+0xac>
40001040:      e311020e       tst      r1, #-536870912      ; 0xe0000000
40001044:      01a01181       moveq      r1, r1, lsl #3
40001048:      03a03008       moveq      r3, #8      ; 0x8
4000104c:      13a03001       movne      r3, #1      ; 0x1
40001050:      e3510201       cmp      r1, #268435456      ; 0x10000000
40001054:      31510000       cmpcc      r1, r0
40001058:      31a01201       movcc      r1, r1, lsl #4
4000105c:      31a03203       movcc      r3, r3, lsl #4
40001060:      3afffffa       bcc      40001050 <__udivsi3+0x2c>
40001064:      e3510102       cmp      r1, #-2147483648      ; 0x80000000
40001068:      31510000       cmpcc      r1, r0
4000106c:      31a01081       movcc      r1, r1, lsl #1
40001070:      31a03083       movcc      r3, r3, lsl #1
40001074:      3afffffa       bcc      40001064 <__udivsi3+0x40>
40001078:      e3a02000       mov      r2, #0      ; 0x0
4000107c:      e1500001       cmp      r0, r1
40001080:      20400001       subcs      r0, r0, r1
40001084:      21822003       orrcs      r2, r2, r3
40001088:      e15000a1       cmp      r0, r1, lsr #1
4000108c:      204000a1       subcs      r0, r0, r1, lsr #1
40001090:      218220a3       orrcs      r2, r2, r3, lsr #1
40001094:      e1500121       cmp      r0, r1, lsr #2
40001098:      20400121       subcs      r0, r0, r1, lsr #2
4000109c:      21822123       orrcs      r2, r2, r3, lsr #2
400010a0:      e15001a1       cmp      r0, r1, lsr #3
400010a4:      204001a1       subcs      r0, r0, r1, lsr #3
400010a8:      218221a3       orrcs      r2, r2, r3, lsr #3
400010ac:      e3500000       cmp      r0, #0      ; 0x0
400010b0:      11b03223       movnes      r3, r3, lsr #4
400010b4:      11a01221       movne      r1, r1, lsr #4
400010b8:      1affffef       bne      4000107c <__udivsi3+0x58>
400010bc:      e1a00002       mov      r0, r2
400010c0:      e12fff1e       bx      lr
400010c4:      03a00001       moveq      r0, #1      ; 0x1
400010c8:      13a00000       movne      r0, #0      ; 0x0
400010cc:      e12fff1e       bx      lr
400010d0:      e3510801       cmp      r1, #65536      ; 0x10000
400010d4:      21a01821       movcs      r1, r1, lsr #16
400010d8:      23a02010       movcs      r2, #16      ; 0x10
400010dc:      33a02000       movcc      r2, #0      ; 0x0
400010e0:      e3510c01       cmp      r1, #256      ; 0x100
400010e4:      21a01421       movcs      r1, r1, lsr #8
400010e8:      22822008       addcs      r2, r2, #8      ; 0x8
400010ec:      e3510010       cmp      r1, #16      ; 0x10
400010f0:      21a01221       movcs      r1, r1, lsr #4
400010f4:      22822004       addcs      r2, r2, #4      ; 0x4
400010f8:      e3510004       cmp      r1, #4      ; 0x4
400010fc:      82822003       addhi      r2, r2, #3      ; 0x3
40001100:      908220a1       addls      r2, r2, r1, lsr #1
40001104:      e1a00230       mov      r0, r0, lsr r2
40001108:      e12fff1e       bx      lr
4000110c:      e52de004       str      lr, [sp, #-4]!
40001110:      eb000034       bl      400011e8 <__div0>
40001114:      e3a00000       mov      r0, #0      ; 0x0
40001118:      e49df004       ldr      pc, [sp], #4

400011e8 <__div0>:
400011e8:      e12fff1e       bx      lr


Cheers,
-Mike.



--- dean_j_greaves <dgreaves@...> wrote:

> 
> Hi,
>   I having a problem with some code i'm developing
> on the LPC2214 
> chip using GNU tools.  
>   I have a simple function that performs a division.
> 
>   unsigned int a=0, b=1000, c=10;
> 
>   a=b/c;
> 
>   When i compile up the code and download to the
> target, the code 
> breaks when i step over this division routine.  When
> i step in to the 
> assembly code for the division, it has compiled in 
> __divsi3 from the 
> libgcc library.
>   The problem appears to be that just before the
> return from the 
> division function, it attempts to restore registers
> from the stack 
> that it never actually push onto the stack.
>   Has anyone ever come across this before.  Any help
> would be 
> gratefully received.
> 
>   Dean
> 
> 
> 
> 



            
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[Non-text portions of this message have been removed]

RE: [lpc2000] Division function

2004-11-03 by Michael Anburaj

Hi Dean,


--- Dean greaves <dgreaves@...> wrote:

> Hi Michael,
> 
>             I wrote a small application this morning
> with just the divide
> routine in it.  When I stepped through the assembly,
> I noticed that most of
> the function is actually missing ???

This could happen is a typical case like this:

void APP_vMain (void)
{
      unsigned int a=0, b=1000, c=10;
 
       //a=test(b,c);
       a = b/c;
 
       CONSOL_Printf("a = %d, b = %d, c =
 %d\n\n",a,b,c);
}

In the above code, the (high optimization) compiler
would know that the values in \ufffdb\ufffd & \ufffdc\ufffd are fixed,
hence it would optimize it away & load the value 100
(result of 1000/10) directly to \ufffda\ufffd. Due to this you
wont see a call made to __udivsi3. Because of this I
purposefully added a subroutine to do the division.

>  It does n't
> look like what you have at
> all.  I'm afraid I'm a bit of a rookie at this, I
> would be grateful for any
> help 
> 
>  
> 
> Please find attached my ELF file
> 

No elf file attachment on this email.

Cheers,
-Mike.



		
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