pseudo_code.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "pseudo_code.h"
#include "pseudo_code.tab.h"

#define STACKSIZE 64000
void *stack;
void *sp;
void *fp;
FnList *functions;
#define BUFSIZE 1000
char buf[BUFSIZE];
void FncList(Node *p);

Function *FindFunction(char *s){
  int i;
  for(i = 0; i < functions->fn_count; i++)
    if(strcasecmp(functions->functions[i]->name, s) == 0)
      return functions->functions[i];
  return NULL;
}

int Add(int *a, int *b) 	{ return *a + *b; }
int Sub(int *a, int *b) 	{ return *a - *b; }
int Mul(int *a, int *b)		{ return (*a) * (*b); }
int Div(int *a, int *b)		{ return (*a) / (*b); }
int leq(int *a, int *b)		{ return (*a) <= (*b); }
int geq(int *a, int *b)		{ return (*a) >= (*b); }
int eq(int *a, int *b)		{ return (*a) == (*b); }
int neq(int *a, int *b)		{ return (*a) != (*b); }
int les(int *a, int *b)		{ return (*a) < (*b); }
int gre(int *a, int *b)		{ return (*a) > (*b); }

void Op2(OpNode *op, int (*fn)(int *a, int *b))
{
  FncList(op->operands[0]);
  sp = sp + sizeof(int);
  FncList(op->operands[1]);
  sp = sp - sizeof(int);
  *(int*)sp = fn(sp, sp + sizeof(int));
}

void ExecuteFunction(Function *fn){
  *(void**)sp = fp;//store reference to previous fncalls variables
  sp = sp + sizeof(void*);//move sp forward to a free spot
  fp = sp;//assign new functions variable space from this location
  sp = sp + fn->var_count * sizeof(int);//move sp forward to space after fn variables
  FncList(fn->body);
  int retvalue = *(int*)fp;
  sp = (void*)fp - sizeof(void*);//restore sp to old value
  fp = *(void**)sp;//restore fp
  *(int*)sp = retvalue;//put fn return value at top of stack
}

void FncList(Node *p){
  if(p == NULL)
    return;
  int i;
  int j;
  int arr;
  int arr2;
  int arr1;
  Function *tmp;
  switch(p->type){
    case tConst:
      *(int*)sp = p->con.value;
      break;
    case tVar:
      //printf("%s %p\n", p->var->name, fp + p->var->index * sizeof(int));
      *(int*)sp = *(int*)(fp + p->var->index * sizeof(int));
      break;
    case tString:
      *(char**)sp = p->str.s;
    case tOp:
      switch(p->op.type){
        case '+':
          Op2(&p->op, Add);
          break;
        case '-':
          Op2(&p->op, Sub);
          break;
        case '*':
          Op2(&p->op, Mul);
          break;
        case '/':
          Op2(&p->op, Div);
          break;
        case '>':
          Op2(&p->op, gre);
          break;
        case '<':
          Op2(&p->op, les);
          break;
        case EQ:
          Op2(&p->op, eq);
          break;
        case NEQ:
          Op2(&p->op, neq);
          break;
        case GEQ:
          Op2(&p->op, geq);
          break;
        case LEQ:
          Op2(&p->op, leq);
          break;
        case '=':
          FncList(p->op.operands[1]);//execute right half and have it stored at sp
          if(p->op.operands[0]->type == tVar) {
            *(int*)(fp + p->op.operands[0]->var->index * sizeof(int)) = *(int*)sp;
          } else {
            arr = *(int*)sp;
            FncList(p->op.operands[0]->op.operands[1]);
            //            printf("%i\n", *(int*)(fp + (p->op.operands[0]->op.operands[0]->var->index + *(int*)sp) * sizeof(int)));
            *(int*)(fp + (p->op.operands[0]->op.operands[0]->var->index + *(int*)sp) * sizeof(int)) = arr;
          }
          break;
        case NOT:
          FncList(p->op.operands[0]);
          *(int*)sp = !*(int*)sp;
          break;
        case PRINT:
          FncList(p->op.operands[0]);
          if(p->op.operands[0]->type == tString)
            printf("%s\n", *(char**)sp);
          else
            printf("%d\n", *(int*)sp);
          break;
        case SWAP:
          if(p->op.operands[0]->type == tVar && p->op.operands[1]->type == tVar) {
            i = p->op.operands[0]->var->index;
            p->op.operands[0]->var->index = p->op.operands[1]->var->index;
            p->op.operands[1]->var->index = i;
          } else {
            if (p->op.operands[0]->type != tVar) {
              FncList(p->op.operands[0]->op.operands[1]);
              arr = *(int*)sp;
              if(p->op.operands[1]->type == tVar) {
                FncList(p->op.operands[1]);
                arr1 = *(int*)sp;
                *(int*)(fp +p->op.operands[1]->var->index * sizeof(int)) =
                    *(int*)(fp + (p->op.operands[0]->op.operands[0]->var->index + arr) * sizeof(int));
                *(int*)(fp + (p->op.operands[0]->op.operands[0]->var->index + arr) * sizeof(int)) = arr1;
              } else {
                FncList(p->op.operands[1]->op.operands[1]);
                arr1 = *(int*)sp;
                arr2 =  *(int*)(fp + (p->op.operands[1]->op.operands[0]->var->index + arr1) * sizeof(int));
                *(int*)(fp + (p->op.operands[1]->op.operands[0]->var->index + arr1) * sizeof(int)) =
                    *(int*)(fp + (p->op.operands[0]->op.operands[0]->var->index + arr) * sizeof(int));
                *(int*)(fp + (p->op.operands[0]->op.operands[0]->var->index + arr) * sizeof(int)) = arr2;
              }
            } else {
              FncList(p->op.operands[1]->op.operands[1]);
              arr = *(int*)sp;
              FncList(p->op.operands[0]);
              *(int*)(fp + p->op.operands[0]->var->index * sizeof(int)) =
                  *(int*)(fp + (p->op.operands[1]->op.operands[0]->var->index + arr) * sizeof(int));
              *(int*)(fp + (p->op.operands[1]->op.operands[0]->var->index + arr) * sizeof(int)) = *(int*)sp;

            }
          }
          break;
        case LEN:
          *(int*)sp = p->op.operands[0]->var->len;
          break;
        case ARRAY:
          FncList(p->op.operands[1]);
          *(int*)sp = *(int*)(fp + (p->op.operands[0]->var->index + *(int*)sp) * sizeof(int));
          break;
        case READ:
          fgets(buf, BUFSIZE, stdin);
          *(int*)(fp + p->op.operands[0]->var->index * sizeof(int)) = atoi(buf);
          break;
        case IF:
          FncList(p->op.operands[0]);
          if( *(int*)sp )
            FncList(p->op.operands[1]);
          break;
        case ELSE:
          FncList(p->op.operands[0]);
          if( *(int*)sp )
            FncList(p->op.operands[1]);
          else
            FncList(p->op.operands[2]);
          break;
        case FOR:
          FncList(p->op.operands[2]);
          j = *(int*)sp;
          FncList(p->op.operands[1]);
          for(*(int*)(fp + p->op.operands[0]->var->index * sizeof(int)) = *(int*)sp;
              *(int*)(fp + p->op.operands[0]->var->index * sizeof(int)) <= j;
              ++(*(int*)(fp + p->op.operands[0]->var->index * sizeof(int)))) {
            FncList(p->op.operands[3]);
          }
          break;
        case FUNC:
          tmp = FindFunction(p->op.operands[0]->var->name);
          if(tmp == NULL || tmp->param_count != p->op.operands[1]->par.n){
            printf("couldn't find function %s (%d)\n", p->op.operands[0]->var->name,
                p->op.operands[1]->par.n);
            exit(0);
            break;
          }else{
            sp = sp + sizeof(void*);
            for(i = 0; i < p->op.operands[1]->par.n; i++){
              sp = sp + sizeof(int);
              FncList(p->op.operands[1]->par.params[i]);
            }
            sp = sp - sizeof(void*) - p->op.operands[1]->par.n * sizeof(int);
            ExecuteFunction(tmp);
          }
      }
      break;
    case tBlock:
      for(i = 0; i < p->block.n; i++)
        FncList(p->block.statements[i]);
      break;
    default:
      break;
  }
} 

int main(int argc, char **argv){
  if(argc < 2){
    printf("No input files!\n");
    return 0;
  }
  int i;
  functions = NULL;
  for(i = 1; i < argc; i++){
    functions = ReadFunctions(argv[i], functions);
  }
  Function *main_fn = FindFunction("MAIN");
  if(main_fn == NULL){
    printf("No main function!\n");
  }else{
    stack = malloc(STACKSIZE);
    sp = stack;
    fp = NULL;
    ExecuteFunction(main_fn);
  }
  FreeFunctions(functions);
  return 0;
}