--- ./pico_ml_wrapper/src/camlpico.c.orig	2008-07-08 22:38:01.000000000 -0600

+++ ./pico_ml_wrapper/src/camlpico.c	2013-07-31 16:11:40.000000000 -0600

@@ -26,6 +26,8 @@

 #include <caml/memory.h>

 #include <picosat.h>

+static PicoSAT *my_picosat;

+

 /* the methods comment were directly taken from 'picosat.h' */

 CAMLprim value unknown(){ return Val_int(PICOSAT_UNKNOWN);}

@@ -35,13 +37,14 @@ CAMLprim value unsatisfiable(){ return V

 CAMLprim value init(value unit)

 {

-    picosat_init();   

+    my_picosat = picosat_init();

     return Val_unit;

 }

 CAMLprim value reset(value unit)

 {

-    picosat_reset();   

+    picosat_reset(my_picosat);

+    my_picosat = NULL;

     return Val_unit;

 }

@@ -55,7 +58,7 @@ CAMLprim value reset(value unit)

  */

 CAMLprim value set_seed(value seed)

 {

-    picosat_set_seed(Unsigned_int_val(seed));

+    picosat_set_seed(my_picosat, Unsigned_int_val(seed));

     return Val_unit;

 }

@@ -65,7 +68,7 @@ CAMLprim value set_seed(value seed)

  */

 CAMLprim value enable_trace(value unit)

 {

-    picosat_enable_trace_generation();

+    picosat_enable_trace_generation(my_picosat);

     return Val_unit;

 }

@@ -76,7 +79,7 @@ CAMLprim value enable_trace(value unit)

  */

 CAMLprim value adjust(value n)

 {

-    picosat_adjust(Int_val(n));

+    picosat_adjust(my_picosat, Int_val(n));

     return Val_unit;

 }

@@ -85,7 +88,7 @@ CAMLprim value adjust(value n)

  */

 CAMLprim value second(value unit)

 {

-    return caml_copy_double(picosat_seconds());

+    return caml_copy_double(picosat_seconds(my_picosat));

 }

 /*------------------------------------------------------------------------*/

@@ -95,7 +98,7 @@ CAMLprim value second(value unit)

  */

 CAMLprim value add(value i)

 {

-    picosat_add(Int_val(i));

+    picosat_add(my_picosat, Int_val(i));

     return Val_unit;

 }

@@ -106,7 +109,7 @@ CAMLprim value add(value i)

  */

 CAMLprim value assume(value i)

 {

-    picosat_assume(Int_val(i));

+    picosat_assume(my_picosat, Int_val(i));

     return Val_unit;

 }

@@ -117,7 +120,7 @@ CAMLprim value assume(value i)

  */

 CAMLprim value sat(value limit)

 {

-    return Val_int(picosat_sat(Int_val(limit)));

+    return Val_int(picosat_sat(my_picosat, Int_val(limit)));

 }

 /* After 'picosat_sat' was called and returned 'PICOSAT_SATISFIABLE', then

@@ -127,7 +130,7 @@ CAMLprim value sat(value limit)

  */

 CAMLprim value deref(value lit)

 {

-    return Val_int(picosat_deref(Int_val(lit)));

+    return Val_int(picosat_deref(my_picosat, Int_val(lit)));

 }

 /* A cheap way of determining an over-approximation of a variable core is to

@@ -138,7 +141,7 @@ CAMLprim value deref(value lit)

  */

 CAMLprim value usedlit(value lit)

 {

-    return Val_int(picosat_usedlit(Int_val(lit)));

+    return Val_int(picosat_usedlit(my_picosat, Int_val(lit)));

 }

 /*------------------------------------------------------------------------*/

@@ -155,7 +158,7 @@ CAMLprim value usedlit(value lit)

  */

 CAMLprim value corelit(value lit)

 {

-    return Val_int(picosat_corelit(Int_val(lit)));

+    return Val_int(picosat_corelit(my_picosat, Int_val(lit)));

 }

 //#include <stdio.h>

@@ -165,7 +168,7 @@ value get_proof(value unit)

 {

     CAMLparam0();

     CAMLlocal1 (array);

-    int* proof = picosat_get_proof();

+    int* proof = picosat_get_proof(my_picosat);

     int size = 0;

     while(proof[size] != EOP){

         size++;