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[DS-5] How to use the compiler intrinsic __softfp?

Jake Lee
Note: This was originally posted on 8th September 2013 at http://forums.arm.com

It's good to know that it's possible to override the global compiler option --fpu=vfpv4 for specific functions with the compiler intrinsic __softfp.

http://infocenter.arm.com/help/topic/com.arm.doc.dui0491i/BABGAEBD.html

But for some reason, I cannot get it to work.


__softfp void myFunction(float a, float B)
{
..
..
..
}


When I declare a function like above it's time for a syntax error. I must be doing something wrong.

Could someone tell me how to use the __softfp intrinsic properly?

Thanks in advance
  • Arm Employee Badge
    Note: This was originally posted on 8th September 2013 at http://forums.arm.com

    [Dud post - sorry]
  • Arm Employee Badge
    Note: This was originally posted on 9th September 2013 at http://forums.arm.com

    __softfp float add(float a, float  b)
    {
      return a + b;
    }
    Compiled with "armcc --cpu=cortex-m4 --fpu=vfpv4 -S" should produce:

    add PROC
            VMOV     s1,r0
            VMOV     s0,r1
            VADD.F32 s0,s1,s0
            VMOV     r0,s0
            BX       lr
            ENDP
    hth
    s.


    [Edited to remove emoticon induced error in code snippet]
  • Note: This was originally posted on 10th September 2013 at http://forums.arm.com


    __softfp float add(float a, float  B)
    {
      return a + b;
    }
    Compiled with "armcc --cpu=cortex-m4 --fpu=vfpv4 -S" should produce:

    add PROC
            VMOV  s1,r0
            VMOV  s0,r1
            VADD.F32 s0,s1,s0
            VMOV  r0,s0
            BX    lr
            ENDP
    hth
    s.


    [Edited to remove emoticon induced error in code snippet]


    sim, you are saving my day again. :)

    It must be an eclipse bug showing a big question mark ("syntax error") at the line with __softfp that distracted me so much that I overlooked the parameters being passed to ARM registers.

    Thank you!