Floating point operations on LPC2138

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1

I am trying to execute the following code on lpc2138:

float a = 10.2;
a = a/2.0;

Debugger stops on second operation (division).

I’m using YAGARTO.

How to enable floating point support in YAGARTO?

2

Please post the generated assembly code.

When I use the current YAGARTO gcc without additional parameters, it generates a call to __divsf3, which is correct for the fpu-less LPC2138 (unless you intend to run the code in Linux with fpu emulator or an EABI environment).

3

Heres my code:

0x000002a8 <AdjustIMU+88>:  ldr r3, [pc, #92]	; 0x30c <AdjustIMU+188>
0x000002ac <AdjustIMU+92>:  str r3, [r11, #-16]
0x000002b0 <AdjustIMU+96>:  ldr r0, [r11, #-16]
0x000002b4 <AdjustIMU+100>: ldr r1, [pc, #84]	; 0x310 <AdjustIMU+192>
0x000002b8 <AdjustIMU+104>: bl  0x3330 <__divsf3>
0x000002bc <AdjustIMU+108>: mov r3, r0
0x000002c0 <AdjustIMU+112>: str r3, [r11, #-16]

So this problem have an evolution…

when I use -msoft-float in gcc option, linker reports this error:

yagarto/lib/gcc/arm-elf/4.2.2\libgcc.a(_muldivsf3.o) uses hardware FP, whereas main.elf uses software FP

arm-elf-objcopy -p libgcc.a shows:

_divsi3.o:     file format elf32-littlearm
private flags = 0: [APCS-32] [FPA float format]

Maybe libgcc.a was built without software floating point support?

2denial Can you post your libgcc.a and libm.a here?

4

Hello Vitaliy,

please take a look here:

http://en.mikrocontroller.net/topic/162806#715107

It is difficult to answer if you post in two forums.

Best regards,

Michael