Fixed interrupt/exception and related initialization

1 files changed, 3 insertions, 2 deletions

diff --git a/lc3.c b/lc3.c
index ca511cf..7a0c4ec 100644
--- a/lc3.c
+++ b/lc3.c
@@ -127,7 +127,7 @@ uint16_t sign_extend(uint16_t value, const int bits)
 void fire(const uint16_t interrupt, const uint16_t priority)
 {
 	const uint16_t current_priority = (registers[REGISTER_PSR] >> 8) & 0x07;
-	if (current_priority >= priority)
+	if (0x00 != interrupt && 0x01 != interrupt && current_priority > priority)
 	{
 		return;
 	}
@@ -321,7 +321,7 @@ void step(const uint16_t instruction)
 		{
 			if (FLAG_SUP & registers[REGISTER_PSR])
 			{
-				fire(0, (registers[REGISTER_PSR] >> 8) & 0x07);
+				fire(0x00, (registers[REGISTER_PSR] >> 8) & 0x07);
 			}
 			else
 			{
@@ -421,6 +421,7 @@ int main(int argc, char ** argv)
 	atexit(restore_terminal);
 	prepare_terminal();
 	registers[REGISTER_PC] = MEMORY_USER;
+	registers[REGISTER_PSR] |= FLAG_SUP;
 	for (;;)
 	{
 		const uint16_t instruction = read_memory(registers[REGISTER_PC]++);