Kinetis Design Studio中的主题 Re: How print double with newlib-nano ?

How print double with newlib-nano ?

jeremypont — Fri, 02 Dec 2016 09:38:28 GMT

Hello,

I try to print double max value (DBL_MAX) on uart and I have hardfault interrupt.

I use newlib-nano with flag -u _printf_float.

I have the same issue with standard libc.

If I print "small" double, it works.

I use kds3.0 with gcc 4.8.

My targer is kl46z on freedom board.

Do you have any idea why it doesn't work ?

Thanks in advance,

Jeremy

Re: How print double with newlib-nano ?

Alice_Yang — Tue, 06 Dec 2016 03:15:08 GMT

Hello Jeremy,

Could you please show your code for print, for sorry i don't know

what's the "double max value" and "small" double .

Alice

Re: How print double with newlib-nano ?

jeremypont — Tue, 06 Dec 2016 07:29:49 GMT

Hello Alice,

I try to print value with this line :

double doubleValue = DBL_MAX;

printf("doubleValue : %.16lE - %.16lf\n", doubleValue, doubleValue);

When I say "small" double, I mean doubleValue = 1.825 for example.

Double maximum value is DBL_MAX from float.h.

Jeremy

Re: How print double with newlib-nano ?

Alice_Yang — Wed, 07 Dec 2016 08:27:52 GMT

Hello Jeremy,

Sorry i do not know what do you want to do , i test on my side ,the result is that :

Does it can meet your requirement ?

If not , please describe it to me what the result you want to .

If yes, i will tell you how to configure on KDS .

Alice

Re: How print double with newlib-nano ?

jeremypont — Wed, 07 Dec 2016 09:20:34 GMT

Hello Alice,

Yes, your example meet my requirement.

I am using cortex m0+ and you seem test on cortex m4 (k22). Am I wrong ?

CM0+ doesn't have fpu, maybe something is wrong with link option ?

My link option are :

arm-none-eabi-g++ -mcpu=cortex-m0plus -mthumb -O3 -fmessage-length=0 -fsigned-char -ffunction-sections -fdata-sections -Wall -g3 -T "../MKL46Z256xxx4_flash.ld" -Xlinker --gc-sections -Wl,-Map,"FreedomKL46Z.map" --specs=nano.specs -u _printf_float -specs=nosys.specs -Xlinker -z -Xlinker muldefs -o "FreedomKL46Z.elf" -Wl,--start-group [*.o files] -lc -lgcc -Wl,--end-group -Lm

Thanks for your help,

Jeremy

Re: How print double with newlib-nano ?

Alice_Yang — Thu, 08 Dec 2016 04:08:58 GMT

Hello Jeremy,

I also use the board of FRDM-KL46.

Please add -specs=rdimon.specs into linker flag :

I also attached my project , you can test on your side .

Hope it helps

Have a great day,
Alice Yang

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