vm.c

   1 #include <stdio.h>
   2 #include <assert.h>
   3 #include "heap.h"
   4 #include "code.h"
   5 #include "symtab.h"
   6 #include "vm.h"
   7
   8 #define STACK_SIZE 4096
   9
  10 static int top = -1;
  11 static int stack[STACK_SIZE];
  12
  13 static int fun_top = -1;
  14 static int fun_stack[STACK_SIZE];
  15
  16 static int pc = 0;              /* program counter */
  17
  18 enum {
  19   O_ADD, O_SUB, O_MUL, O_DIV, O_MOD,
  20   O_EQL, O_NE, O_GEQL, O_LEQL, O_GT, O_LT };
  21
  22 static void
  23 bin_op(int op)
  24 {
  25   assert(top >= 1);
  26   switch(op) {
  27   case O_ADD:
  28     stack[top-1] = stack[top-1] + stack[top];
  29     break;
  30   case O_SUB:
  31     stack[top-1] = stack[top-1] - stack[top];
  32     break;
  33   case O_MUL:
  34     stack[top-1] = stack[top-1] * stack[top];
  35     break;
  36   case O_DIV:
  37     stack[top-1] = stack[top-1] / stack[top];
  38     break;
  39   case O_MOD:
  40     stack[top-1] = stack[top-1] % stack[top];
  41     break;
  42   case O_EQL:
  43     stack[top-1] = stack[top-1] == stack[top];
  44     break;
  45   case O_NE:
  46     stack[top-1] = stack[top-1] != stack[top];
  47     break;
  48   case O_GEQL:
  49     stack[top-1] = stack[top-1] >= stack[top];
  50     break;
  51   case O_LEQL:
  52     stack[top-1] = stack[top-1] <= stack[top];
  53     break;
  54   case O_GT:
  55     stack[top-1] = stack[top-1] > stack[top];
  56     break;
  57   case O_LT:
  58     stack[top-1] = stack[top-1] < stack[top];
  59     break;
  60   default:
  61     fprintf(stderr, "Operacao %d nao reconhecida\n", op);
  62     break;
  63   }
  64   --top;
  65   pc++;
  66 }
  67
  68 void
  69 vm_halt(int arg)
  70 {
  71 }
  72
  73 void
  74 vm_add(int arg)
  75 {
  76   bin_op(O_ADD);
  77 }
  78
  79 void
  80 vm_sub(int arg)
  81 {
  82   bin_op(O_SUB);
  83 }
  84
  85 void
  86 vm_mul(int arg)
  87 {
  88   bin_op(O_MUL);
  89 }
  90
  91 void
  92 vm_div(int arg)
  93 {
  94   bin_op(O_DIV);
  95 }
  96
  97 void
  98 vm_mod(int arg)
  99 {
 100   bin_op(O_MOD);
 101 }
 102
 103 void
 104 vm_cmp_eql(int arg)
 105 {
 106   bin_op(O_EQL);
 107 }
 108
 109 void
 110 vm_cmp_ne(int arg)
 111 {
 112   bin_op(O_NE);
 113 }
 114
 115 void
 116 vm_cmp_geql(int arg)
 117 {
 118   bin_op(O_GEQL);
 119 }
 120
 121 void
 122 vm_cmp_leql(int arg)
 123 {
 124   bin_op(O_LEQL);
 125 }
 126
 127 void
 128 vm_cmp_gt(int arg)
 129 {
 130   bin_op(O_GT);
 131 }
 132
 133 void
 134 vm_cmp_lt(int arg)
 135 {
 136   bin_op(O_LT);
 137 }
 138
 139 void
 140 vm_load_var(int arg)
 141 {
 142   int off = stack[top--];
 143   stack[++top] = data_get(arg, off);
 144   pc++;
 145 }
 146
 147 void
 148 vm_load_int(int arg)
 149 {
 150   stack[++top] = arg;
 151   pc++;
 152 }
 153
 154 void
 155 vm_load_off(int arg)
 156 {
 157   stack[++top] = arg;
 158   pc++;
 159 }
 160
 161 void
 162 vm_store(int arg)
 163 {
 164   int off = stack[top--];
 165   assert(top >= 0);
 166   data_put(arg, off, stack[top]);
 167   top--;
 168   pc++;
 169 }
 170
 171 void
 172 vm_jmp_false(int arg)
 173 {
 174   if (stack[top] == 0)
 175     pc = arg;
 176   else
 177     pc++;
 178   top--;
 179 }
 180
 181 void
 182 vm_goto(int arg)
 183 {
 184   pc = arg;
 185 }
 186
 187 void
 188 vm_write_int(int arg)
 189 {
 190   printf("%d\n", stack[top]);
 191   top--;
 192   pc++;
 193 }
 194
 195 void
 196 vm_call(int arg)
 197 {
 198   scope++;
 199   pc = arg;
 200 }
 201
 202 void
 203 vm_push_int(int arg)
 204 {
 205   fun_stack[++fun_top] = arg;
 206   pc++;
 207 }
 208
 209 void
 210 vm_push_var(int arg)
 211 {
 212   fun_stack[++fun_top] = data_get(arg, stack[top--]);
 213   pc++;
 214 }
 215
 216 void
 217 vm_ret(int arg)
 218 {
 219   int nargs;
 220
 221   pc = fun_stack[fun_top--];
 222   nargs = fun_stack[fun_top--];
 223
 224   top -= nargs;
 225
 226   assert(fun_top >= -1 && top >= -1);
 227
 228   scoperem(scope--);
 229 }
 230
 231 int
 232 vm_loop(void)
 233 {
 234   while (code[pc].op != HALT) {
 235     ops[code[pc].op].op(code[pc].arg);
 236   }
 237
 238   return 0;
 239 }