I am using mingw64 under cygwin environment. I am trying to use dllwrap command to create dll file but unable to create with following error message

$ dllwrap -o fcnsuite.dll fcnsuite.o
dllwrap: no export definition file provided.
Creating one, but that may not be what you want

I am unable to understand the problem.
nm command gives following output

$ nm fcnsuite.o
0000000000000000 b .bss
0000000000000000 d .data
0000000000000000 p .pdata
0000000000000000 r .rdata
0000000000000000 r .rdata$zzz
0000000000000000 t .text
0000000000000000 r .xdata
U cos
U exp
0000000000000000 T g01
00000000000003a6 T g02
000000000000060d T g03
000000000000071d T g04
0000000000000b70 T g05
0000000000000e6a T g06
0000000000000fef T g07
000000000000178e T g08
0000000000001920 T g09
0000000000001dfb T g10
0000000000002086 T g11
0000000000002125 T g12
0000000000002411 T g13
00000000000025fa T g14
00000000000028a4 T g15
0000000000002a77 T g16
00000000000037d1 T g17
0000000000003bd8 T g18
00000000000041c3 T g19
0000000000004777 T g20
0000000000004e68 T g21
0000000000005183 T g22
0000000000005806 T g23
0000000000005a95 T g24
U log
U pow
U sin
U sqrt

Please help me to cope up with this problem.