Hey Forum
I'm working on a protocol and adding some telemetry which requires floating point arithmetic to convert a VBat value. I'm taking an existing protocol (cflie, but it doesn't really matter which...) and I've added code to the effect of:
// Bytes 6, 7, 8, and 9 are the Vbat in float
float vBat;
memcpy(&vBat, &packet[5], sizeof(float));
Telemetry.value[TELEM_DSM_FLOG_VOLT1] = (s32)(vBat*10);
TELEMETRY_SetUpdated(TELEM_DSM_FLOG_VOLT1);
Which produces linker errors complaining about the floating point lib functions being used (mult, and float to int):
+ Compiling 'protocol/cflie_nrf24l01.c' as module
+ Building 'objs/devo7e/cflie_nrf24l01.bin'
objs/devo7e/cflie_nrf24l01.o_: In function `cflie_callback':
cflie_nrf24l01.c:(.text.cflie_callback+0x11a): undefined reference to `__aeabi_fmul'
cflie_nrf24l01.c:(.text.cflie_callback+0x11e): undefined reference to `__aeabi_f2iz'
I've spent a ton of time googling this sort of issue and best I can tell, it means I'm not linking in libgcc properly OR I need to be using gcc instead of ld for my linking (because apparently ld is notoriously bad at paths). However, no definitive solutions yet, and I've tried a variety of things. Converting the LD call to a CC call in the target/common/devo/Makefile.inc led me down a rabbit trail that I ultimately gave up on, but maybe that's the right way to go.
Anyway -- I imagine someone has got to have needed floats and tackled this problem before. Any ideas on the easiest solution -- preferably something that's portable and doesn't require a hard path to libgcc.a?
Thanks
Sean
