New opcode DCOP_DEREF (4) "dereferences" a pointer to return the value pointed to. Using the getstring() function in the previous example, if it was called with the parameter signature "p" instead of ">", to get the address directly, you could then get the value as follows:
map1 buffer,s,0
map2 address,b,4
dlctl.opcode = DCOP_CALL
xcall DYNLIB, dlctl, "getstring(p)v", address ! get ptr into address
dlctl.opcode = DCOP_DEREF
xcall DYNLIB, dlctl, address, buffer ! copy string pointed to by address
! into buffer
This can be useful in dealing with functions that return a structure containing pointers to strings, rather than the strings themselves. But any time you are dealing with direct pointers like this, you run the risk of a segmentation fault if there is any discrepancy between the expected and actual parameters or behavior of the underlying function.
