2017/advent23.c

   1 #define _GNU_SOURCE 1
   2 #include <stdio.h>
   3 #include <string.h>
   4 #include <stdlib.h>
   5 #include <unistd.h>
   6 #include <stdbool.h>
   7 #include <ctype.h>
   8
   9 #if 0
  10
  11 typedef struct state state;
  12 struct state {
  13   long long regs[26];
  14   unsigned int pc;
  15   int count;
  16   int mul;
  17 } states;
  18
  19 char *program[50]; // sized based on pre-inspecting file
  20 int instr;
  21
  22 long long
  23 get (state *s, const char *value)
  24 {
  25   if (isalpha(*value))
  26     return s->regs[*value - 'a'];
  27   return atoi (value);
  28 }
  29
  30 void
  31 set (state *s, const char *reg, long long value)
  32 {
  33   s->regs[*reg - 'a'] = value;
  34   if (getenv ("DEBUG"))
  35     printf (" %s=%lld\n", reg, value);
  36 }
  37
  38 bool
  39 run (state *s, int id)
  40 {
  41   while (s->pc < instr) {
  42     char arg1[10], arg2[10];
  43     if (getenv ("DEBUG"))
  44       printf ("p%d instr %d at pc %d: %s\n", id, s->count, s->pc,
  45               program[s->pc]);
  46     if (!(s->count % 10000))
  47       printf ("\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b%10d h=%lld", s->count,
  48              s->regs['h' - 'a']);
  49     if (s->pc == 8) {
  50       printf ("\nstarting computation at count %d,", s->count);
  51       for (int i = 'a'; i <= 'h'; i++)
  52         printf (" %c=%lld", i, s->regs[i - 'a']);
  53       printf ("\n");
  54     }
  55     sscanf (program[s->pc], "%*s %9s %9s", arg1, arg2);
  56     switch ((program[s->pc][0] << 8) + program[s->pc][1]) {
  57     case ('s' << 8) + 'e': // set X Y
  58       set (s, arg1, get (s, arg2));
  59       break;
  60     case ('s' << 8) + 'u': // sub X Y
  61       set (s, arg1, get (s, arg1) - get (s, arg2));
  62       break;
  63     case ('a' << 8) + 'd': // add X Y
  64       set (s, arg1, get (s, arg1) + get (s, arg2));
  65       break;
  66     case ('m' << 8) + 'u': // mul X Y
  67       s->mul++;
  68       set (s, arg1, get (s, arg1) * get (s, arg2));
  69       break;
  70     case ('m' << 8) + 'o': // mod X Y
  71       set (s, arg1, get (s, arg1) % get (s, arg2));
  72       break;
  73     case ('j' << 8) + 'n': // jnz X Y
  74       if (get (s, arg1))
  75         s->pc += get (s, arg2) - 1;
  76       break;
  77     default:
  78       return 1;
  79     }
  80     s->count++;
  81     s->pc++;
  82   }
  83   return false;
  84 }
  85
  86 int main(int argc, char **argv)
  87 {
  88   char buf[400]; // sized based on pre-inspecting file
  89   int nread = fread (buf, 1, sizeof buf, stdin);
  90   char *p = buf;
  91   while (p < buf + nread) {
  92     program[instr++] = p;
  93     p = strchr (p, '\n');
  94     *p++ = '\0';
  95   }
  96   printf ("program consists of %d instructions\n", instr);
  97   states.regs[0] = 1;
  98   if (argc > 1)
  99     states.regs[0] = atoi (argv[1]);
 100   if (argc > 2) {
 101     states.regs[1] = atoi (argv[2]);
 102     states.pc = 2;
 103   }
 104   if (argc > 3)
 105     states.regs[2] = atoi (argv[3]);
 106   run (&states, 0);
 107   printf ("\nafter %d operations, reg h is %lld\n", states.count,
 108           states.regs['h' - 'a']);
 109   return 0;
 110 }
 111
 112 #else
 113
 114 int main(int argc, char **argv)
 115 {
 116   int a = 1, b = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0;
 117   bool skip_a = false;
 118   if (argc > 1)
 119     a = atoi (argv[1]);
 120   if (argc > 2) {
 121     b = atoi (argv[2]);
 122     skip_a = true;
 123   }
 124   if (argc > 3)
 125     c = atoi (argv[3]);
 126   if (skip_a)
 127     goto l9;
 128
 129  l1: // set b 57
 130   b = 57;
 131  l2: // set c b
 132   c = b;
 133  l3: // jnz a 2
 134   if (a)
 135     goto l5;
 136  l4: // jnz 1 5
 137   goto l9;
 138  l5: // mul b 100
 139   b *= 100;
 140  l6: // sub b -100000
 141   b -= -100000;
 142  l7: // set c b
 143   c = b;
 144  l8: // sub c -17000
 145   c -= -17000;
 146  l9: // set f 1
 147   f = 1;
 148  l10: // set d 2
 149   d = 2;
 150  l11: // set e 2
 151   e = 2;
 152  l12: // set g d
 153   g = d;
 154  l13: // mul g e
 155   g *= e;
 156  l14: // sub g b
 157   g -= b;
 158  l15: // jnz g 2
 159   if (g)
 160     goto l17;
 161  l16: // set f 0
 162   printf ("b=%d c=%d d=%d e=%d f=%d g=%d h=%d\n", b, c, d, e, f, g, h);
 163   f = 0;
 164  l17: // sub e -1
 165   e -= -1;
 166  l18: // set g e
 167   g = e;
 168  l19: // sub g b
 169   g -= b;
 170  l20: // jnz g -8
 171   if (g)
 172     goto l12;
 173  l21: // sub d -1
 174   d -= -1;
 175  l22: // set g d
 176   g = d;
 177  l23: // sub g b
 178   g -= b;
 179  l24: // jnz g -13
 180   if (g)
 181     goto l11;
 182  l25: // jnz f 2
 183   if (f)
 184     goto l27;
 185  l26: // sub h -1
 186   printf (" b=%d c=%d d=%d e=%d f=%d g=%d h=%d\n", b, c, d, e, f, g, h);
 187   h -= -1;
 188  l27: // set g b
 189   g = b;
 190  l28: // sub g c
 191   g -= c;
 192  l29: // jnz g 2
 193   if (g)
 194     goto l31;
 195  l30: // jnz 1 3
 196   goto end;
 197  l31: // sub b -17
 198   b -= -17;
 199  l32: // jnz 1 -23
 200   goto l9;
 201  end:
 202   printf ("final value of h: %d\n", h);
 203 }
 204
 205 #endif