c7a4f0ed2b24d36d13c80af60ce536e3d44b7e0c

prior implimentation just cleared n flag while specification states n should be set or cleared according to the most significant bit of the result.

bug find credit goes to: Shay Green <gblargg@gmail.com>

	modified:   simavr/sim/sim_core.c

diff --git a/simavr/sim/sim_core.c b/simavr/sim/sim_core.c
index 03d46ffd6fe83e512a56451ecbf15a321897d419..8e7af22ef623ebec63ebd4d217380f8804adae9a 100644 (file)
--- a/simavr/sim/sim_core.c
+++ b/simavr/sim/sim_core.c
@@ -1118,7 +1118,7 @@ avr_flashaddr_t avr_run_one(avr_t * avr)
                                                        _avr_set_r(avr, r, res);
                                                        avr->sreg[S_Z] = res == 0;
                                                        avr->sreg[S_C] = vr & 1;
-                                                       avr->sreg[S_N] = 0;
+                                                       avr->sreg[S_N] = res >> 7;
                                                        avr->sreg[S_V] = avr->sreg[S_N] ^ avr->sreg[S_C];
                                                        avr->sreg[S_S] = avr->sreg[S_N] ^ avr->sreg[S_V];
                                                        SREG();