[Add] software simulator add

lasim/la32r.cc

@@ -0,0 +1,115 @@
+#include <common.h>
+#include <la32r.hh>
+
+namespace {
+using u64 = uint64_t;
+using i64 = int64_t;
+
+using u32 = uint32_t;
+using i32 = int32_t;
+
+SystemBus *sysbus;
+
+enum regenum {
+     R0,  R1,  R2,  R3,  R4,  R5,  R6,  R7,  R8,  R9,
+    R10, R11, R12, R13, R14, R15, R16, R17, R18, R19,
+    R20, R21, R22, R23, R24, R25, R26, R27, R28, R29,
+    R30, R31, PC
+};
+
+enum PLV {
+    PLV0, 
+    // PLV1, 
+    // PLV2, 
+    PLV3, 
+} PrivilegeLevel ;
+
+class Registers {
+private:
+    u32 regs_[32] = {0};
+    u32 pc_ = 0;
+
+public:
+    Registers() = default;
+
+    u32 get(u32 idx) {
+        panicifnot((0 <= idx && 32 >= idx) || idx == PC);
+        if (idx == PC) {
+            return pc_;
+        }
+
+        if (0 <= idx && 32 >= idx) {
+            return regs_[idx];
+        }
+
+        panic("Unexpected register access");
+    }
+
+    void set(u32 idx, u32 data) {
+        panicifnot((0 <= idx && 32 >= idx) || idx == PC);
+        if (idx == PC) {
+            pc_ = data;
+        }
+
+        if (0 <= idx && 32 >= idx) {
+            regs_[idx] = data;
+        }
+
+        panic("Unexpected register access");
+
+    }
+
+    u32 &operator[](u32 idx) {
+        if (idx == PC) {
+            return pc_;
+        }
+
+        if (0 <= idx && 32 >= idx) {
+            return regs_[idx];
+        }
+
+        panic("Unexpected register access");
+    }
+} Regs ;
+
+constexpr u32 getbits(u32 hi, u32 lo, u32 data) {
+    data = data >> lo;
+    u32 mask = ((u64) 0x1 << (hi + 1)) - 1;
+    return data & mask;
+}
+
+void decode_and_exec(u32 inst) {
+
+    if (getbits(31, 15, inst) == 0b00000000000100000) {
+        u32 rd = getbits( 4,  0, inst);
+        u32 rj = getbits( 9,  5, inst);
+        u32 rk = getbits(14, 10, inst);
+
+        u32 tmp = Regs[rj] + Regs[rk];
+        Regs[rd] = getbits(31, 0, tmp);
+        return;
+    }
+
+    panic("Invalid operation or have not implemented yet.");
+}
+
+u32 fetch() {
+    u32 inst;
+    sysbus->read32(inst, Regs[PC]);
+    return inst;
+}
+
+}
+
+
+LA32R::LA32R(SystemBus *bus) {
+    sysbus = bus;
+
+    Regs[PC] = 0x0000'0000;
+}
+
+void LA32R::Step(unsigned in) {
+    u32 inst = fetch();
+    decode_and_exec(inst);
+    Regs[PC] += 4;
+}