Here is the gist for showing how to send string from c to go without a copy, for sending an float32 array from c to go without copy, please see here
Below is the documentation for converting between a c string and a go string:
// From https://golang.org/cmd/cgo/
// A few special functions convert between Go and C types by making copies of the data.
// Go string to C string
// The C string is allocated in the C heap using malloc.
// It is the caller's responsibility to arrange for it to be
// freed, such as by calling C.free (be sure to include stdlib.h
