Remove dependency of ALU operation encoding on MIPS instruction format.

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

4 files changed, 21 insertions, 24 deletions

diff --git a/qtmips_machine/alu.cpp b/qtmips_machine/alu.cpp
index fa9b7d2..8016444 100644
--- a/qtmips_machine/alu.cpp
+++ b/qtmips_machine/alu.cpp
@@ -45,6 +45,8 @@ std::uint32_t machine::alu_operate(enum AluOp operation, std::uint32_t s, std::u
     discard = false;
 
     switch(operation) {
+        case ALU_OP_NOP:
+            return 0;
         case ALU_OP_SLL:
             return t << sa;
         case ALU_OP_SRL:
@@ -59,12 +61,6 @@ std::uint32_t machine::alu_operate(enum AluOp operation, std::uint32_t s, std::u
         case ALU_OP_SRAV:
             // Note: same note as in case of SRA
             return (std::int32_t)t >> s;
-        case ALU_OP_JR:
-            // Do nothing as we solve this when we are handling program counter in instruction decode (handle_pc)
-            return 0;
-        case ALU_OP_JALR:
-            // Pass return value in rt to save PC after isntruction, program counter is handled in handle_pc
-            return t;
         case ALU_OP_MOVZ:
             // Signal discard of result when condition is not true
             discard = t != 0;
@@ -73,8 +69,6 @@ std::uint32_t machine::alu_operate(enum AluOp operation, std::uint32_t s, std::u
             // Same note as for MOVZ applies here
             discard = t == 0;
             return discard ? 0: s;
-        case ALU_OP_BREAK:
-             return 0;
         case ALU_OP_MFHI:
             return regs->read_hi_lo(true);
         case ALU_OP_MTHI:
@@ -136,6 +130,10 @@ std::uint32_t machine::alu_operate(enum AluOp operation, std::uint32_t s, std::u
             return t << 16;
         case  ALU_OP_PASS_T: // Pass s argument without change for JAL
             return t;
+        case ALU_OP_BREAK:
+            return 0;
+        case  ALU_OP_SYSCALL: // Pass s argument without change for JAL
+            return 0;
         default:
             throw QTMIPS_EXCEPTION(UnsupportedAluOperation, "Unknown ALU operation", QString::number(operation, 16));
     }
diff --git a/qtmips_machine/core.cpp b/qtmips_machine/core.cpp
index 8bf3977..b75e31b 100644
--- a/qtmips_machine/core.cpp
+++ b/qtmips_machine/core.cpp
@@ -231,7 +231,7 @@ struct Core::dtMemory Core::memory(const struct dtExecute &dt) {
     emit memory_memwrite_value(memwrite);
     emit memory_regw_num_value(dt.rwrite);
 
-    if (dt.excause == EXCAUSE_BREAK)
+    if ((dt.excause == EXCAUSE_BREAK) || (dt.excause == EXCAUSE_SYSCALL))
         emit memory_break_reached();
 
     return {
diff --git a/qtmips_machine/instruction.cpp b/qtmips_machine/instruction.cpp
index 8aea469..9df45d8 100644
--- a/qtmips_machine/instruction.cpp
+++ b/qtmips_machine/instruction.cpp
@@ -98,7 +98,7 @@ static const struct InstructionMap  alu_instruction_map[] = {
      .flags = FLAGS_ALU_T_R_STD_SHV},
     {"SRAV",   IT_R, ALU_OP_SRAV, NOMEM, nullptr,
      .flags = FLAGS_ALU_T_R_STD_SHV},
-    {"JR",     IT_R, ALU_OP_JR, NOMEM, nullptr,
+    {"JR",     IT_R, ALU_OP_NOP, NOMEM, nullptr,
      .flags = IMF_SUPPORTED | IMF_BJR_REQ_RS | IMF_JUMP},
     {"JALR",   IT_R, ALU_OP_PASS_T, NOMEM, nullptr,
      .flags = IMF_SUPPORTED | IMF_REGD | IMF_REGWRITE | IMF_BJR_REQ_RS | IMF_PC8_TO_RT | IMF_JUMP},
diff --git a/qtmips_machine/machinedefs.h b/qtmips_machine/machinedefs.h
index f4a4a81..526a05e 100644
--- a/qtmips_machine/machinedefs.h
+++ b/qtmips_machine/machinedefs.h
@@ -57,26 +57,24 @@ enum ExceptionCause {
 };
 
 enum AluOp : std::uint8_t {
-    ALU_OP_SLL = 0,
-    ALU_OP_SRL = 2,
+    ALU_OP_NOP,
+    ALU_OP_SLL,
+    ALU_OP_SRL,
     ALU_OP_SRA,
     ALU_OP_SLLV,
-    ALU_OP_SRLV = 6,
+    ALU_OP_SRLV,
     ALU_OP_SRAV,
-    ALU_OP_JR,
-    ALU_OP_JALR,
     ALU_OP_MOVZ,
     ALU_OP_MOVN,
-    ALU_OP_BREAK = 13,
-    ALU_OP_MFHI = 16,
+    ALU_OP_MFHI,
     ALU_OP_MTHI,
     ALU_OP_MFLO,
     ALU_OP_MTLO,
-    ALU_OP_MULT = 24,
-    ALU_OP_MULTU = 25,
-    ALU_OP_DIV = 26,
-    ALU_OP_DIVU = 27,
-    ALU_OP_ADD = 32,
+    ALU_OP_MULT,
+    ALU_OP_MULTU,
+    ALU_OP_DIV,
+    ALU_OP_DIVU,
+    ALU_OP_ADD,
     ALU_OP_ADDU,
     ALU_OP_SUB,
     ALU_OP_SUBU,
@@ -84,10 +82,11 @@ enum AluOp : std::uint8_t {
     ALU_OP_OR,
     ALU_OP_XOR,
     ALU_OP_NOR,
-    ALU_OP_SLT = 42,
+    ALU_OP_SLT,
     ALU_OP_SLTU,
-    ALU_OP_LUI = 64, // We don't care about exact index for this one
+    ALU_OP_LUI, // We don't care about exact index for this one
     ALU_OP_PASS_T, // Pass t argument without change for JAL
+    ALU_OP_BREAK,
     ALU_OP_SYSCALL,
     ALU_OP_UNKNOWN,
     ALU_OP_LAST // First impossible operation (just to be sure that we don't overflow)