Convert unsigned long long to double in C

Question

I realize this question could be processor dependent, but hopefully someone can point me in the right direction. For the life of me, I cannot figure out how to convert an unsigned long long int representing nanoseconds to a double representing seconds in C (I'm using a 32-bit big-endian PowerPC 405 for this particular test, and a GNU C99 compiler).

I've tried:

unsigned long long int nanoseconds = 1234567890LLU;
double nanoseconds_d = nanoseconds*1e-9;

Also:

nanoseconds_d = ((double) nanoseconds)*1e-9;

For both cases, I just get 0. What am I doing wrong here?

EDITED TO ADD FULL EXAMPLE

#include <stdio.h>
#include <stdlib.h>

int
main( int argc, char *argv[] )
{
    unsigned long long int nanoseconds = 1234567890LLU;
    double nanoseconds_d = nanoseconds * 1e-9;
    printf("%g\n", nanoseconds_d);

    return 0;
}

MAKEFILE

SRCS    = simple.c    
INCLUDE := -I$(PWD)            
CFLAGS  := -O0 -g3 -Wall -fmessage-length=0 -mhard-float -fsigned-char -D_REENTRANT
LIBS    := -lc

OBJS = $(SRCS:.c=.o)
PROG = $(SRCS:.c=).out

all: $(PROG)

$(PROG): $(OBJS)
    @echo "Linking object files with output."
    $(CC) -o $(PROG) $(OBJS) $(LIBS)
    @echo "Linking complete."

$(OBJS): $(SRCS)
    @echo "Starting compilation."
    $(CC) $(CFLAGS) $(INCLUDE) -c $<
    @echo "Compilation complete."   

clean::
    @$(RM) *.o *.out

Answer 1

Works here when using %g to print

#include <stdlib.h>
#include <stdio.h>

int main(){
    unsigned long long int nanoseconds = 1234567890LLU;
    double nanoseconds_d = nanoseconds*1e-9;
    printf("%g\n", nanoseconds_d);

    nanoseconds_d = ((double) nanoseconds)*1e-9;
    printf("%g\n", nanoseconds_d);
}

outputs

1.23457
1.23457