Computer-Architecture-Sumi👩‍💻

ls8/cpu.c

@@ -8,18 +8,19 @@
 void cpu_load(struct cpu *cpu)
 {
   char data[DATA_LEN] = {
-    // From print8.ls8
-    0b10000010, // LDI R0,8
-    0b00000000,
-    0b00001000,
-    0b01000111, // PRN R0
-    0b00000000,
-    0b00000001  // HLT
+      // From print8.ls8
+      0b10000010, // LDI R0,8
+      0b00000000,
+      0b00001000,
+      0b01000111, // PRN R0
+      0b00000000,
+      0b00000001 // HLT
   };
 
   int address = 0;
 
-  for (int i = 0; i < DATA_LEN; i++) {
+  for (int i = 0; i < DATA_LEN; i++)
+  {
     cpu->ram[address++] = data[i];
   }
 
@@ -31,10 +32,11 @@ void cpu_load(struct cpu *cpu)
  */
 void alu(struct cpu *cpu, enum alu_op op, unsigned char regA, unsigned char regB)
 {
-  switch (op) {
-    case ALU_MUL:
-      // TODO
-      break;
+  switch (op)
+  {
+  case ALU_MUL:
+    // TODO
+    break;
 
     // TODO: implement more ALU ops
   }
@@ -47,21 +49,75 @@ void cpu_run(struct cpu *cpu)
 {
   int running = 1; // True until we get a HLT instruction
 
-  while (running) {
+  while (running)
+  {
     // TODO
     // 1. Get the value of the current instruction (in address PC).
+    unsigned char IR = cpu_ram_read(cpu, cpu->pc);
     // 2. Figure out how many operands this next instruction requires
+    //IR gives you the current instuction
+    //reading from the bitwise right shift will give you the number of operands:
+    unsigned char operandA = 0;
+    unsigned char operandB = 0;
+    unsigned int numOp = IR >> 6;
+
     // 3. Get the appropriate value(s) of the operands following this instruction
+    if (numOp == 2)
+    {
+      unsigned char operandA = cpu_ram_read(cpu, (cpu->pc + 1) & 0xff);
+      unsigned char operandB = cpu_ram_read(cpu, (cpu->pc + 2) & 0xff);
+    }
     // 4. switch() over it to decide on a course of action.
+    switch (IR)
+    {
+    case LDI:
+      // change the value of reg @ operanA to operandB;
+      printf("%d\n", cpu->reg[operandB]);
+      cpu->reg[operandA] = operandB;
+      cpu->pc += 2;
+      printf("%d\n", cpu->reg[operandB]);
+      break;
+    case PRN:
+      cpu->pc += 2;
+      printf("%d\n", cpu->reg[operandA]);
+      break;
+    case HLT:
+      running = 0;
+      break;
+    default:
+      printf("Error");
+      break;
+    }
     // 5. Do whatever the instruction should do according to the spec.
     // 6. Move the PC to the next instruction.
   }
 }
 
+// ram functions
+unsigned char cpu_ram_read(struct cpu *cpu, unsigned char index)
+{
+  return cpu->ram[index];
+}
+
+void cpu_ram_write(struct cpu *cpu, unsigned mar, unsigned char mdr)
+{
+  cpu->ram[mar] = mdr;
+}
+
 /**
  * Initialize a CPU struct
  */
 void cpu_init(struct cpu *cpu)
 {
   // TODO: Initialize the PC and other special registers
-}
+  for (int i = 0; i <= 6; i++)
+  {
+    cpu->reg[i] = 0;
+  }
+
+  cpu->reg[7] = 0;
+  cpu->pc = 0;
+
+  // set everything in ram to 0
+  memset(cpu->ram, 0, sizeof cpu->ram);
+}

ls8/cpu.h

@@ -2,27 +2,32 @@
 #define _CPU_H_
 
 // Holds all information about the CPU
-struct cpu {
+struct cpu
+{
   // TODO
   // PC
+  unsigned int pc;
   // registers (array)
+  unsigned char reg[8];
   // ram (array)
+  unsigned char ram[256];
 };
 
 // ALU operations
-enum alu_op {
-	ALU_MUL
-	// Add more here
+enum alu_op
+{
+  ALU_MUL
+  // Add more here
 };
 
 // Instructions
 
 // These use binary literals. If these aren't available with your compiler, hex
 // literals should be used.
 
-#define LDI  0b10000010
-#define HLT  0b00000001
-#define PRN  0b01000111
+#define LDI 0b10000010
+#define HLT 0b00000001
+#define PRN 0b01000111
 // TODO: more instructions here. These can be used in cpu_run().
 
 // Function declarations