+ // by default, trap to M-mode, unless delegated to S-mode
+ reg_t bit = t.cause();
+ reg_t deleg = state.medeleg;
+ if (bit & ((reg_t)1 << (max_xlen-1)))
+ deleg = state.mideleg, bit &= ~((reg_t)1 << (max_xlen-1));
+ if (state.prv <= PRV_S && bit < max_xlen && ((deleg >> bit) & 1)) {
+ // handle the trap in S-mode
+ state.pc = state.stvec;
+ state.scause = t.cause();
+ state.sepc = epc;
+ if (t.has_badaddr())
+ state.sbadaddr = t.get_badaddr();
+
+ reg_t s = state.mstatus;
+ s = set_field(s, MSTATUS_SPIE, get_field(s, MSTATUS_UIE << state.prv));
+ s = set_field(s, MSTATUS_SPP, state.prv);
+ s = set_field(s, MSTATUS_SIE, 0);
+ set_csr(CSR_MSTATUS, s);
+ set_privilege(PRV_S);
+ } else {
+ state.pc = DEFAULT_MTVEC + 0x40 * state.prv;
+ state.mcause = t.cause();
+ state.mepc = epc;
+ if (t.has_badaddr())
+ state.mbadaddr = t.get_badaddr();
+
+ reg_t s = state.mstatus;
+ s = set_field(s, MSTATUS_MPIE, get_field(s, MSTATUS_UIE << state.prv));
+ s = set_field(s, MSTATUS_MPP, state.prv);
+ s = set_field(s, MSTATUS_MIE, 0);
+ set_csr(CSR_MSTATUS, s);
+ set_privilege(PRV_M);
+ }
+