Computer-Architecture - Scott Bren

README.md

@@ -1,4 +1,4 @@
-# Computer Architecture
+# Computer Architecture -
 
 ## Project
 
@@ -7,22 +7,24 @@
 ## Task List: add this to the first comment of your Pull Request
 
 ### Day 1: Get `print8.ls8` running
-- [ ] Inventory what is here
-- [ ] Implement `struct cpu` in `cpu.h`
-- [ ] Add RAM functions `cpu_ram_read` and `cpu_ram_write`
-- [ ] Implement `cpu_init()`
-- [ ] Implement the core of `cpu_run()`
-- [ ] Implement the `HLT` instruction handler
-- [ ] Add the `LDI` instruction
-- [ ] Add the `PRN` instruction
+- [x] Inventory what is here
+- [x] Implement `struct cpu` in `cpu.h`
+- [x] Add RAM functions `cpu_ram_read` and `cpu_ram_write`
+- [x] Implement `cpu_init()`
+- [x] Implement the core of `cpu_run()`
+- [x] Implement the `HLT` instruction handler
+- [x] Add the `LDI` instruction
+- [x] Add the `PRN` instruction
 
 ### Day 2: Add the ability to load files dynamically, get `mult.ls8` and `stack.ls8` running
-- [ ] Un-hardcode the machine code
-- [ ] Implement the `cpu_load` function to load an `.ls8` file given the filename passed in as an argument
-- [ ] Implement a Multiply instruction and Print the result (run `mult8.ls8`)
+- [x] Un-hardcode the machine code
+- [x] Implement the `cpu_load` function to load an `.ls8` file given the filename passed in as an argument
+- [x] Implement a Multiply instruction and Print the result (run `mult8.ls8`)
+
+### Day 3:
 - [ ] Implement the System Stack and be able to run the `stack.ls8` program
 
-### Day 3: Get `call.ls8` running
+### Day 4: Get `call.ls8` running
 - [ ] Implement the CALL and RET instructions
 - [ ] Implement Subroutine Calls and be able to run the `call.ls8` program
 

ls8/cpu.c

@@ -1,29 +1,52 @@
 #include "cpu.h"
+#include "string.h"
+#include "stdio.h"
+#include <stdlib.h>
 
-#define DATA_LEN 6
+#define DATA_LEN 12
 
 /**
  * Load the binary bytes from a .ls8 source file into a RAM array
  */
-void cpu_load(struct cpu *cpu)
+void cpu_load(struct cpu *cpu, char *program)
 {
-  char data[DATA_LEN] = {
-    // 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++) {
-    cpu->ram[address++] = data[i];
+
+  FILE *fp;
+
+  char line[1024];
+
+  fp = fopen(program, "r");
+
+  if( fp == NULL) {
+    fprintf(stderr, "Error opening file.\n");
+    exit(1);
   }
 
-  // TODO: Replace this with something less hard-coded
+  int i = 0;
+  while( fgets(line, sizeof(line), fp) != NULL ) {
+    char *endPtr;
+    unsigned char byte = strtol(line, &endPtr, 2);
+
+    if(endPtr == line) {
+      continue;
+    }
+
+    cpu_ram_write(cpu, i, byte);
+    i++;
+  }
+
+  fclose(fp);
+
+}
+
+unsigned char cpu_ram_read(struct cpu *cpu, unsigned char address)
+{
+  return cpu->ram[address];
+}
+
+void cpu_ram_write(struct cpu *cpu, int address, unsigned char value)
+{
+  cpu->ram[address] = value;
 }
 
 /**
@@ -47,14 +70,76 @@ void cpu_run(struct cpu *cpu)
 {
   int running = 1; // True until we get a HLT instruction
 
+  int stack[256];
+  int sp = 7;
+
+  //int PC = cpu->PC;
+  //unsigned char value;
+
   while (running) {
     // TODO
     // 1. Get the value of the current instruction (in address PC).
+    unsigned char instruction = cpu_ram_read(cpu, cpu->PC);
     // 2. Figure out how many operands this next instruction requires
     // 3. Get the appropriate value(s) of the operands following this instruction
+    unsigned char operandA = cpu_ram_read(cpu, cpu->PC + 1);
+    unsigned char operandB = cpu_ram_read(cpu, cpu->PC + 2);
+
     // 4. switch() over it to decide on a course of action.
     // 5. Do whatever the instruction should do according to the spec.
     // 6. Move the PC to the next instruction.
+    switch(instruction) {
+
+      case HLT:
+        running = 0;
+        break;
+
+      case LDI:
+        cpu->registers[operandA] = operandB;
+        cpu->PC += 3;
+        break;
+
+      case PRN:
+        printf("%d\n", cpu->registers[operandA]);
+        cpu->PC += 2;
+        break;
+
+      case MUL:
+        cpu->registers[operandA] = (cpu->registers[operandA] * cpu->registers[operandB]);
+        //test that MUL completed successfully
+        printf("%d\n", cpu->registers[operandA]);
+        cpu->PC += 2;
+        break;
+
+      case PUSH:
+        sp--;
+        stack[sp] = cpu->registers[operandA];
+        cpu->PC += 2;
+        break;
+
+      case POP:
+        cpu->registers[operandA] = stack[sp];
+        sp++;
+        cpu->PC += 2;
+        break;
+
+      case CALL:
+        sp--;
+        stack[sp] = cpu->registers[operandA];
+        cpu->PC = cpu->registers[operandA];
+
+        cpu_ram_read(cpu, cpu->PC);
+        break;
+
+      case RET:
+        cpu->registers[operandA] = stack[sp];
+        sp++;
+
+        cpu->PC = cpu->registers[operandA];
+        break;
+
+
+    }
   }
 }
 
@@ -63,5 +148,10 @@ void cpu_run(struct cpu *cpu)
  */
 void cpu_init(struct cpu *cpu)
 {
-  // TODO: Initialize the PC and other special registers
+  cpu->PC = 0;
+
+  memset(cpu->registers, 0, 8*sizeof(unsigned char));
+
+  memset(cpu->ram, 0, 8*sizeof(unsigned char));
+
 }

ls8/cpu.h

@@ -5,8 +5,11 @@
 struct cpu {
   // TODO
   // PC
+  int PC;
   // registers (array)
+  unsigned char registers[8];
   // ram (array)
+  unsigned char ram[8];
 };
 
 // ALU operations
@@ -23,11 +26,16 @@ enum alu_op {
 #define LDI  0b10000010
 #define HLT  0b00000001
 #define PRN  0b01000111
+#define MUL  0b10100010
+#define PUSH 0b01000101
+#define POP  0b01000110
+#define CALL 0b01010000
+#define RET  0b00010001
 // TODO: more instructions here. These can be used in cpu_run().
 
 // Function declarations
 
-extern void cpu_load(struct cpu *cpu);
+extern void cpu_load(struct cpu *cpu, char *program);
 extern void cpu_init(struct cpu *cpu);
 extern void cpu_run(struct cpu *cpu);
 

ls8/ls8.c

@@ -1,16 +1,28 @@
 #include <stdio.h>
 #include "cpu.h"
+#include <stdlib.h>
 
 /**
  * Main
  */
-int main(void)
+int main(int argc, char **argv)
 {
   struct cpu cpu;
+  char *program;
 
-  cpu_init(&cpu);
-  cpu_load(&cpu);
-  cpu_run(&cpu);
+  if (argc < 2) {
+    fprintf(stderr, "Please specify which program the LS8 should run.\nUsage: ls8 program\n");
+    exit(1);
+
+  } else {
+    program = argv[1];
+
+    printf("%s\n", program);
+
+    cpu_init(&cpu);
+    cpu_load(&cpu, program);
+    cpu_run(&cpu);
+  }
 
   return 0;
 }