Problem with sdiv.. about libfixmath HOT 19 CLOSED

I've not had a chance to test these recent changes but I can confirm that the 
r49 code works just fine, so you're best bet on a quick solution is to revert 
your copy of fix16.c to revision 49 and work with that until this can be solved.

Sorry for the inconvenience.

Could not reproduce bug on x86 using the attached test.c. I'll try with 
cortex-m3 later today.

@SHAGGYNEMISIS

Can you provide the compiler options you are using, and also the exact compiler 
version?

Some other temporary replacement code you could use is this fast-newton-raphson 
algorithm:

fix16_t rcp(fix16_t b)
{
    bool n = (b < 0);
    if (n) b = -b;

    int s = 0;
    for (; b > fix16_one; b >>= 1, s--);
    for (; b < (fix16_one >> 1); b <<= 1, s++);

    fix16_t x
        = 185043 - fix16_mul(b, 123362);

    unsigned i;
    for (i = 0; i < 3; i++)
        x = fix16_mul(x, (0x00020000 - fix16_mul(b, x)));
    x <<= s;
    return (n ? -x : x);
}

fix16_t fdiv(fix16_t a, fix16_t b)
{
    return fix16_mul(a, rcp(b));
}

@Flatmush

Fails for 15.0 / 5.0 etc. I don't think such temporary hacks are necessary, I 
can fix the bug as soon as I can reproduce it. It is most probably some 
compiler-specific issue, because the unittests would catch it otherwise.

gimme me few mins ill provide the makefile and the code 

the fpArith.c contains the part of the code that i need for my working..

[deleted comment]

Nope this didn't give  the desired result  
Div (-2) 0xfffe0000, (-1)0xffff0000 = 0x80000000

Try the test.c I attached in comment 3. Your code is too messy and I can't get 
it easily to compile.

I tried the test.c on Cortex-M3 simulator also, the division works just fine.

Yes i did try the test.c file the result is the same.. i.e. incorrect answer.
I will post the cleaned up test file soon.. Sorry to keep you waiting

Ok, good to know that test.c gives incorrect answer. Can you still give the gcc 
version, you can get it with "arm-none-eabi-gcc --version".

arm-none-eabi-gcc (Sourcery G++ Lite 2010q1-188) 4.4.1
Copyright (C) 2009 Free Software Foundation, Inc.

Hmm, I cannot repeat the bug using that compiler version either. Could you post 
also the .elf file from your test.c compilation?

Might take a while will try asap.. :)

fyi this is compilation command ...
arm-none-eabi-g++ -mcpu=cortex-m3 -mthumb -mfpu=vfp -msoft-float 
-mfloat-abi=soft -O0 -Wl,-Map=main.map,--cref,--gc-sect
ions -lc -lm -lgcc -lstdc++  -T..//Common/LPC17xx.ld  
I will post the elf.. soon 

If there's nothing new on this thread then I'm going to close it since the bug 
can't be reproduced and is very likely a compiler/code issue.