Add instructions ., , and %, void values, quine example

Signed-off-by: Mavridis Philippe <[email protected]>

Author: blu256

README.md

@@ -49,7 +49,10 @@ Below is a short summary of the currently available instructions:
   >  right-shift value by 1
   \  reset value in current cell
   *  replace value with a random number between 0 and the original value
+  %  replace value with the instruction at position indicated by original value
   ~  swap value with register
+  .  assign current value to register
+  ,  assign current register to value
 ```
 
 ### Pointer instructions
@@ -78,10 +81,12 @@ following instructions to jump back to them.
 
 ### Conditions
 ```
-  &  if current value is zero, skip next instruction
-  `  if current value is zero, exit
+  &  if current value is void, skip next instruction
+  `  if current value is void, exit
 ```
 
+The following control characters are considered void values: 0 (NUL), 10 (LF), 13 (CR).
+
 ### Input/output
 ```
    :  get value and place it in current cell

examples/quine.duh

@@ -0,0 +1 @@
+|.%`;~+_

keycodes.h

@@ -4,12 +4,19 @@
  * Date:       2021/11/21  *
  ***************************/
 
+/* Control characters */
+#define CR 13
+#define LF 10
+
 /* Value instructions */
 #define VAL_INCR 43  // +  increase value
 #define VAL_DECR 45  // -  decrease value
 #define VAL_RSET 92  // \  reset value
 #define VAL_RAND 42  // *  0 < random < current value
+#define VAL_INST 37  // %  get instruction at value position
 #define VAL_SWAP 126 // ~  swap value and register
+#define VAL_VTOR 46  // .  assign value to register
+#define VAL_RTOV 44  // ,  assign register to value
 #define VAL_LSFT 60  // <  left shift by 1
 #define VAL_RSFT 62  // >  right shift by 1
 

main.c

@@ -52,6 +52,11 @@ void term_setup()
 	tcsetattr( STDIN_FILENO, TCSANOW, &newt );
 }
 
+int is_void(int value)
+{
+	return !value || value == CR || value == LF;
+}
+
 int main( int argc, char* argv[] )
 {
 	if( argc != 2 )
@@ -147,7 +152,6 @@ int main( int argc, char* argv[] )
 				while(! feof(source) )
 				{
 					tmp = getc(source);
-			
 					if( tmp == JMP_MARK )
 						break;
 				}
@@ -184,12 +188,12 @@ int main( int argc, char* argv[] )
             }
 
 			case CND_SKIP:
-				if(!*memptr)
+				if (is_void(*memptr))
 					fseek(source, 1, SEEK_CUR);
 				break;
 
 			case CND_TERM:
-				if(!*memptr)
+				if (is_void(*memptr))
 				{
 					cleanup();
 					return 0;
@@ -200,6 +204,15 @@ int main( int argc, char* argv[] )
 				*memptr = get_rand(*memptr);
 				break;
 
+			case VAL_INST:
+			{
+				int old = ftell(source);
+				fseek(source, *memptr, SEEK_SET);
+				*memptr = getc(source);
+				fseek(source, old, SEEK_SET);
+				break;
+			}
+
 			case VAL_SWAP:
 			{
 				wchar_t tmp = *memptr;
@@ -208,6 +221,14 @@ int main( int argc, char* argv[] )
 				break;
 			}
 
+			case VAL_VTOR:
+				reg = *memptr;
+				break;
+
+			case VAL_RTOV:
+				*memptr = reg;
+				break;
+
 			#ifdef DEBUG
 			case 84: // T stack trace
 				debug_print_trace();
@@ -241,7 +262,7 @@ int main( int argc, char* argv[] )
 
 		#ifdef SAFETY
 		/* Check position in memory */
-		if( memptr == &memory[ sizeof(memory) / sizeof(memory[0]) ] )
+		if( memptr >= &memory[ sizeof(memory) / sizeof(memory[0]) ] )
 		{
 			printf("\nFATAL: tried to access out-of-bounds memory!\n");