Merge pull request #32 from nubok/patch-2

Avoid undefined behavior - bp is initialized when setting up the stack

c4.c

@@ -10,6 +10,7 @@
 #include <stdlib.h>
 #include <memory.h>
 #include <unistd.h>
+#include <fcntl.h>
 
 char *p, *lp, // current position in source code
      *data;   // data/bss pointer
@@ -35,7 +36,7 @@ enum {
 // opcodes
 enum { LEA ,IMM ,JMP ,JSR ,BZ  ,BNZ ,ENT ,ADJ ,LEV ,LI  ,LC  ,SI  ,SC  ,PSH ,
        OR  ,XOR ,AND ,EQ  ,NE  ,LT  ,GT  ,LE  ,GE  ,SHL ,SHR ,ADD ,SUB ,MUL ,DIV ,MOD ,
-       OPEN,READ,CLOS,PRTF,MALC,MSET,MCMP,EXIT };
+       OPEN,READ,CLOS,PRTF,MALC,FREE,MSET,MCMP,EXIT };
 
 // types
 enum { CHAR, INT, PTR };
@@ -56,7 +57,7 @@ void next()
         while (le < e) {
           printf("%8.4s", &"LEA ,IMM ,JMP ,JSR ,BZ  ,BNZ ,ENT ,ADJ ,LEV ,LI  ,LC  ,SI  ,SC  ,PSH ,"
                            "OR  ,XOR ,AND ,EQ  ,NE  ,LT  ,GT  ,LE  ,GE  ,SHL ,SHR ,ADD ,SUB ,MUL ,DIV ,MOD ,"
-                           "OPEN,READ,CLOS,PRTF,MALC,MSET,MCMP,EXIT,"[*++le * 5]);
+                           "OPEN,READ,CLOS,PRTF,MALC,FREE,MSET,MCMP,EXIT,"[*++le * 5]);
           if (*le <= ADJ) printf(" %d\n", *++le); else printf("\n");
         }
       }
@@ -352,7 +353,7 @@ int main(int argc, char **argv)
   memset(data, 0, poolsz);
 
   p = "char else enum if int return sizeof while "
-      "open read close printf malloc memset memcmp exit void main";
+      "open read close printf malloc free memset memcmp exit void main";
   i = Char; while (i <= While) { next(); id[Tk] = i++; } // add keywords to symbol table
   i = OPEN; while (i <= EXIT) { next(); id[Class] = Sys; id[Type] = INT; id[Val] = i++; } // add library to symbol table
   next(); id[Tk] = Char; // handle void type
@@ -462,7 +463,7 @@ int main(int argc, char **argv)
   if (src) return 0;
 
   // setup stack
-  sp = (int *)((int)sp + poolsz);
+  bp = sp = (int *)((int)sp + poolsz);
   *--sp = EXIT; // call exit if main returns
   *--sp = PSH; t = sp;
   *--sp = argc;
@@ -477,7 +478,7 @@ int main(int argc, char **argv)
       printf("%d> %.4s", cycle,
         &"LEA ,IMM ,JMP ,JSR ,BZ  ,BNZ ,ENT ,ADJ ,LEV ,LI  ,LC  ,SI  ,SC  ,PSH ,"
          "OR  ,XOR ,AND ,EQ  ,NE  ,LT  ,GT  ,LE  ,GE  ,SHL ,SHR ,ADD ,SUB ,MUL ,DIV ,MOD ,"
-         "OPEN,READ,CLOS,PRTF,MALC,MSET,MCMP,EXIT,"[i * 5]);
+         "OPEN,READ,CLOS,PRTF,MALC,FREE,MSET,MCMP,EXIT,"[i * 5]);
       if (i <= ADJ) printf(" %d\n", *pc); else printf("\n");
     }
     if      (i == LEA) a = (int)(bp + *pc++);                             // load local address
@@ -517,6 +518,7 @@ int main(int argc, char **argv)
     else if (i == CLOS) a = close(*sp);
     else if (i == PRTF) { t = sp + pc[1]; a = printf((char *)t[-1], t[-2], t[-3], t[-4], t[-5], t[-6]); }
     else if (i == MALC) a = (int)malloc(*sp);
+    else if (i == FREE) free((void *)*sp);
     else if (i == MSET) a = (int)memset((char *)sp[2], sp[1], *sp);
     else if (i == MCMP) a = memcmp((char *)sp[2], (char *)sp[1], *sp);
     else if (i == EXIT) { printf("exit(%d) cycle = %d\n", *sp, cycle); return *sp; }