Use irq 3 (HW1) for Rx and irq 2 (HW0) for Tx to be compatible with SPIM.

Jump to address 0x8000180 by default and to EBase + 0x180
when EBase is set to be compatible with real MIPS CPU.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>

5 files changed, 30 insertions, 18 deletions

diff --git a/qtmips_machine/cop0state.cpp b/qtmips_machine/cop0state.cpp
index 9c5fa1c..9957560 100644
--- a/qtmips_machine/cop0state.cpp
+++ b/qtmips_machine/cop0state.cpp
@@ -40,7 +40,6 @@
 
 using namespace machine;
 
-
 // sorry, unimplemented: non-trivial designated initializers not supported
 
 static enum Cop0State::Cop0Regsisters cop0reg_map[32][8] = {
@@ -81,25 +80,25 @@ static enum Cop0State::Cop0Regsisters cop0reg_map[32][8] = {
 // sorry, unimplemented: non-trivial designated initializers not supported
 
 const Cop0State::cop0reg_desc_t Cop0State::cop0reg_desc[Cop0State::COP0REGS_CNT] = {
-    [Cop0State::Unsupported] = {"Unsupported", 0x00000000,
+    [Cop0State::Unsupported] = {"Unsupported", 0x00000000, 0x00000000,
         &Cop0State::read_cop0reg_default, &Cop0State::write_cop0reg_default},
-    [Cop0State::UserLocal] = {"UserLocal", 0xffffffff,
+    [Cop0State::UserLocal] = {"UserLocal", 0xffffffff, 0x00000000,
         &Cop0State::read_cop0reg_default, &Cop0State::write_cop0reg_default},
-    [Cop0State::BadVAddr] = {"BadVAddr", 0x00000000,
+    [Cop0State::BadVAddr] = {"BadVAddr", 0x00000000, 0x00000000,
         &Cop0State::read_cop0reg_default, &Cop0State::write_cop0reg_default},
-    [Cop0State::Count] =    {"Count", 0x00000000,
+    [Cop0State::Count] =    {"Count", 0x00000000, 0x00000000,
         &Cop0State::read_cop0reg_default, &Cop0State::write_cop0reg_default},
-    [Cop0State::Compare] =  {"Compare", 0x00000000,
+    [Cop0State::Compare] =  {"Compare", 0x00000000, 0x00000000,
         &Cop0State::read_cop0reg_default, &Cop0State::write_cop0reg_default},
-    [Cop0State::Status] =   {"Status",  Status_IE | Status_IntMask,
+    [Cop0State::Status] =   {"Status",  Status_IE | Status_IntMask, 0x00000000,
         &Cop0State::read_cop0reg_default, &Cop0State::write_cop0reg_default},
-    [Cop0State::Cause] =    {"Cause", 0x00000000,
+    [Cop0State::Cause] =    {"Cause", 0x00000000, 0x00000000,
         &Cop0State::read_cop0reg_default, &Cop0State::write_cop0reg_default},
-    [Cop0State::EPC] =      {"EPC", 0xffffffff,
+    [Cop0State::EPC] =      {"EPC", 0xffffffff, 0x00000000,
         &Cop0State::read_cop0reg_default, &Cop0State::write_cop0reg_default},
-    [Cop0State::EBase] =    {"EBase", 0xfffffffc,
+    [Cop0State::EBase] =    {"EBase", 0xfffffffc, 0x80000000,
         &Cop0State::read_cop0reg_default, &Cop0State::write_cop0reg_default},
-    [Cop0State::Config] =   {"Config", 0x00000000,
+    [Cop0State::Config] =   {"Config", 0x00000000, 0x00000000,
         &Cop0State::read_cop0reg_default, &Cop0State::write_cop0reg_default},
 };
 
@@ -166,7 +165,7 @@ bool Cop0State::operator!=(const Cop0State &c) const {
 
 void Cop0State::reset() {
     for (int i = 0; i < COP0REGS_CNT; i++)
-        this->cop0reg[i] = 0;
+        this->cop0reg[i] = cop0reg_desc[i].init_value;
 }
 
 void Cop0State::update_execption_cause(enum ExceptionCause excause, bool in_delay_slot) {
@@ -197,7 +196,8 @@ bool Cop0State::core_interrupt_request() {
     irqs &= Status_IntMask;
 
     return !!(irqs && cop0reg[(int)Status] & Status_IntMask &&
-              !(cop0reg[(int)Status] & Status_EXL));
+           !(cop0reg[(int)Status] & Status_EXL) &&
+           !(cop0reg[(int)Status] & Status_ERL));
 }
 
 void Cop0State::set_status_exl(bool value) {
@@ -206,3 +206,7 @@ void Cop0State::set_status_exl(bool value) {
     else
         cop0reg[(int)Status] &= ~Status_EXL;
 }
+
+std::uint32_t Cop0State::exception_pc_address() {
+    return cop0reg[(int)EBase] + 0x180;
+}
diff --git a/qtmips_machine/cop0state.h b/qtmips_machine/cop0state.h
index 649348e..06be9a7 100644
--- a/qtmips_machine/cop0state.h
+++ b/qtmips_machine/cop0state.h
@@ -64,6 +64,7 @@ public:
     enum StatusReg {
         Status_IE =      0x00000001,
         Status_EXL =     0x00000002,
+        Status_ERL =     0x00000004,
         Status_IntMask = 0x0000ff00,
         Status_Int0 =    0x00000100,
     };
@@ -82,6 +83,7 @@ public:
     void reset(); // Reset all values to zero
 
     bool core_interrupt_request();
+    std::uint32_t exception_pc_address();
 
 public slots:
     void set_interrupt_signal(uint irq_num, bool active);
@@ -102,8 +104,10 @@ private:
     struct cop0reg_desc_t {
         const char *name;
         std::uint32_t write_mask;
+        std::uint32_t init_value;
         reg_read_t reg_read;
         reg_write_t reg_write;
+
     };
 
     static const cop0reg_desc_t cop0reg_desc[COP0REGS_CNT];
diff --git a/qtmips_machine/core.cpp b/qtmips_machine/core.cpp
index 22dfdc8..351ffb0 100644
--- a/qtmips_machine/core.cpp
+++ b/qtmips_machine/core.cpp
@@ -141,7 +141,7 @@ bool Core::handle_exception(Core *core, Registers *regs, ExceptionCause excause,
         if (cop0state->read_cop0reg(Cop0State::EBase) != 0) {
             if (excause == EXCAUSE_INT) {
                 cop0state->set_status_exl(true);
-                regs->pc_abs_jmp(cop0state->read_cop0reg(Cop0State::EBase));
+                regs->pc_abs_jmp(cop0state->exception_pc_address());
             }
         }
     }
diff --git a/qtmips_machine/machinedefs.h b/qtmips_machine/machinedefs.h
index eb7f6d4..8ccc81c 100644
--- a/qtmips_machine/machinedefs.h
+++ b/qtmips_machine/machinedefs.h
@@ -58,8 +58,12 @@ enum AccessControl {
 };
 
 enum ExceptionCause {
-    EXCAUSE_NONE     =  0,
-    EXCAUSE_INT      =  1,
+    EXCAUSE_NONE     =  0,  // Use zero as default value when no exception is pending
+    EXCAUSE_INT      =  1,  // Int is 0 on real CPU and in Cause regsiter
+    EXCAUSE_ADDRL    =  4,
+    EXCAUSE_ADDRS    =  5,
+    EXCAUSE_IBUS     =  6,
+    EXCAUSE_DBUS     =  7,
     EXCAUSE_SYSCALL  =  8,
     EXCAUSE_BREAK    =  9,
     EXCAUSE_OVERFLOW = 12,
diff --git a/qtmips_machine/serialport.cpp b/qtmips_machine/serialport.cpp
index 7eb9c53..8db5725 100644
--- a/qtmips_machine/serialport.cpp
+++ b/qtmips_machine/serialport.cpp
@@ -53,8 +53,8 @@ SerialPort::SerialPort() {
     rx_st_reg = 0;
     rx_data_reg = 0;
     tx_st_reg = 0;
-    tx_irq_level = 0;
-    rx_irq_level = 1;
+    tx_irq_level = 2;  // HW Interrupt 0
+    rx_irq_level = 3;  // HW Interrupt 1
     tx_irq_active = false;
     rx_irq_active = false;
 }