day 5 part 1

CMakeLists.txt

@@ -6,4 +6,5 @@ set(CMAKE_C_STANDARD 99)
 add_executable(day1 day1.c)
 add_executable(day2 day2.c)
 add_executable(day3 day3.c)
-add_executable(day4 day4.c)
+add_executable(day4 day4.c)
+add_executable(day5 day5.c intcode.c)

day5.c

@@ -0,0 +1,15 @@
+//
+// Created by red on 05/12/19.
+//
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "intcode.h"
+
+int main(int argc, char **argv) {
+  char* filename = argv[1];
+  intcode* v = read_file(filename, 2048);
+  int input[1] = { 1 };
+  v->input_tape = input;
+  run(v);
+}

intcode.c

@@ -0,0 +1,130 @@
+//
+// Created by red on 05/12/19.
+//
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "intcode.h"
+
+ival out_val(int n) {
+  ival v;
+  v.type = IVAL_OUT;
+  v.num = n;
+  return v;
+}
+
+ival err_val(int n) {
+  ival v;
+  v.type = IVAL_ERR;
+  v.err = n;
+  return v;
+}
+
+ival end_val() {
+  ival v;
+  v.type = IVAL_END;
+  return v;
+}
+
+ival cont_val() {
+  ival v;
+  v.type = IVAL_CONT;
+  return v;
+}
+
+void ival_print(ival v) {
+  switch (v.type) {
+  case IVAL_ERR: {
+    switch (v.err) {
+    case IERR_OUT_OF_BOUNDS: printf("error: read/write out of bounds\n");
+      break;
+    case IERR_BAD_OP: printf("error: bad opcode\n");
+      break;
+    }
+  }
+  case IVAL_OUT: {
+    printf("Output value: %d\n", v.num);
+  }
+  }
+}
+
+ival step (intcode* m) {
+  int opcode = m->tape[m->index];
+  int addr_mode[2];
+  addr_mode[0] = (opcode / 100) % 10;
+  addr_mode[1] = (opcode / 1000) % 10;
+  opcode = opcode % 100;
+  switch (opcode) {
+  case 99: return end_val();
+  case 4: {
+    int v;
+    if (addr_mode[0] == 0) { v = m->tape[m->tape[m->index+1]]; }
+    else { v = m->tape[m->index+1]; }
+    m->index += 2;
+    return out_val(v);
+  }
+  case 3: {
+    int  i = m->tape[m->index+1];
+    m->index += 2;
+    m->tape[i] = m->input_tape[0];
+    m->input_tape = m->input_tape+1;
+    return cont_val();
+  }
+  default: {
+    int a;
+    int b;
+    if (opcode != 1 && opcode != 2) return err_val(IERR_BAD_OP);
+    if (addr_mode[0] == 0) { a = m->tape[m->tape[m->index+1]]; }
+    else { a = m->tape[m->index+1]; }
+    if (addr_mode[1] == 0) { b = m->tape[m->tape[m->index+2]]; }
+    else { b = m->tape[m->index+2]; }
+    switch (opcode) {
+    case 1: {
+      m->tape[m->tape[m->index+3]] = a+b;
+      m->index += 4;
+      break;
+    }
+    case 2: {
+      m->tape[m->tape[m->index+3]] = a*b;
+      m->index += 4;
+      break;
+    }
+    }
+  }
+  return cont_val();
+  }
+}
+
+ival run (intcode* m) {
+ for (;;) {
+   size_t i = m->index;
+   printf("DEBUG: next 4 values: %d %d %d %d\n", m->tape[i], m->tape[i+1], m->tape[i+2], m->tape[i+3]);
+   ival v = step(m);
+   switch (v.type) {
+   case IVAL_ERR:
+   case IVAL_END: return v;
+   case IVAL_OUT: ival_print(v);
+     break;
+   default: break;
+   }
+ }
+};
+
+intcode *read_file(char *filename, size_t buf_size) {
+  int* tape = calloc(buf_size, sizeof(int));
+  memset((void*) tape, 0, sizeof(int)*buf_size);
+  FILE* file = fopen(filename, "r");
+  size_t i;
+  for (i = 0; i < buf_size; i++) {
+    int a;
+    int err = fscanf(file, "%d,", &a);
+    if (err == EOF) break;
+    tape[i] = a;
+  }
+  static intcode v;
+  v.tape = tape;
+  v.index = 0;
+  v.tape_l = i;
+  return &v;
+}

intcode.h

@@ -0,0 +1,27 @@
+//
+// Created by red on 05/12/19.
+//
+
+#include <stddef.h>
+
+#ifndef AOC2019_INTCODE_H
+#define AOC2019_INTCODE_H
+
+
+enum {IERR_BAD_OP, IERR_OUT_OF_BOUNDS};
+enum {IVAL_OUT, IVAL_ERR, IVAL_END, IVAL_CONT};
+typedef struct {
+  int type;
+  int num;
+  int err;
+} ival;
+typedef struct {
+  int* tape;
+  size_t tape_l;
+  size_t index;
+  int* input_tape;
+} intcode;
+ival step (intcode* m);
+ival run (intcode* m);
+intcode* read_file(char* filename, size_t buf_size);
+#endif //AOC2019_INTCODE_H