// run function 'fn' on UraniumVCPU with 'ctx'
// return value is r[0].sx/rax
long uvm_run_interp(const void *fn, const uvm_context_t *ctx);

// this api is used to make target's function pointer under your control
//
// make a wrapper for function 'fn' with 'usrctx','callback'
// return value is a new function pointer which will run under our VCPU
// you can replace this pointer to target's function pointer
// like C++-Vtable/Script-Native-Bridge
// if return null, you should check errno
const void *uvm_make_callee(const void *fn, void *usrctx,
                            uvm_interp_callback_t callback);

// opcode type for callback args
typedef enum uvm_optype_t {
  vcop_read,    // memory read
  vcop_write,   // memory write
  vcop_call,    // function call
  vcop_return,  // function return
#if __ARM__
  vcop_svc,  // arm syscall
#else
  vcop_syscall,  // intel syscall
#endif
  vcop_ifetch,  // interpreter fetch instruction
} uvm_optype_t;

// callback args
typedef struct uvm_callback_args_t {
  // your own context passed for uvm_run_interp/uvm_make_callee
  const void *usrctx;
  // uvm execution context
  uvm_regs_t *uvmctx;
  // current opcode
  uvm_optype_t op;
  union {
    // for vcop_read/vcop_write/vcop_ifetch
    struct {
      const void *src;
      void *dst;
      int byte;
    } rw;
    // for vcop_call
    struct {
      const void *callee;
    } call;
    // for vcop_return
    struct {
      const void *hitaddr;  // which address hit return
    } ret;
    // for vcop_svc
    struct {
      // arm
      // parameters are in armctx->r[0...6]
      // syscall number from armctx->r[7]
      //
      // arm64
      // parameters are in arm64ctx->x
      // syscall number
      //
      // x86/x64
      // ...
      int sysno;
    } svc;
  } info;
} uvm_callback_args_t;