Add stop program functionality (#6)

* Add stop program functionality

* Using volatile for running field

---------

Co-authored-by: Richard Dominick <[email protected]>

Author: tohlh

vm/include/sinter.h

@@ -33,7 +33,8 @@ typedef enum {
   sinter_fault_internal_error = 9,
   sinter_fault_function_arity = 10,
   sinter_fault_program_error = 11,
-  sinter_fault_uninitialised_heap = 12
+  sinter_fault_uninitialised_heap = 12,
+  sinter_fault_stopped = 13
 } sinter_fault_t;
 
 typedef struct {
@@ -61,6 +62,14 @@ sinter_fault_t sinter_run(const unsigned char *code, const size_t code_size, sin
  */
 void sinter_setup_heap(void *heap, size_t size);
 
+/**
+ * Stops the currently running program.
+ *
+ * This function stops the currently running program.
+*/
+
+void sinter_stop(void);
+
 /**
  * The type of a string printer function.
  *

vm/include/sinter/vm.h

@@ -19,7 +19,7 @@ extern "C" {
 #endif
 
 struct sistate {
-  bool running;
+  volatile bool running;
   sinter_fault_t fault_reason;
   const opcode_t *pc;
   const opcode_t *program;
@@ -84,6 +84,8 @@ SINTER_INLINEIFC __attribute__((warn_unused_result)) sinanbox_t siexec_nanbox(si
 
 bool sivm_equal(sinanbox_t l, sinanbox_t r);
 
+void sistop(void);
+
 #define SISTATE_CURADDR (sistate.pc - sistate.program)
 #define SISTATE_ADDRTOPC(addr) (sistate.program + (addr))
 

vm/src/main.c

@@ -133,3 +133,7 @@ return;
   siheap_size = size;
 #endif
 }
+
+void sinter_stop(void) {
+  sistop();
+}

vm/src/vm.c

@@ -159,6 +159,12 @@ static void main_loop(void) {
   (void) previous_pc;
 #endif
   while (1) {
+    if (!sistate.running) {
+      SIDEBUG("The program has been stopped by the user.\n");
+      sifault(sinter_fault_stopped);
+      return;
+    }
+
 #ifdef SINTER_DEBUG_MEMORY_CHECK
     debug_memorycheck();
 #endif
@@ -924,3 +930,12 @@ sinanbox_t siexec(const svm_function_t *fn, siheap_env_t *parent_env, uint8_t ar
 
   return ret;
 }
+
+void sistop(void) {
+  sistate.running = false;
+  sistate.fault_reason = sinter_fault_stopped;
+  sistate.pc = NULL;
+  sistate.program = NULL;
+  sistate.program_end = NULL;
+  sistate.env = NULL;
+}