example bf interpreter

examples/bf.nds

@@ -0,0 +1,112 @@
+{
+  // source
+  var src = ">++++++++++>+>+[
+    [+++++[>++++++++<-]>.<++++++[>--------<-]+<<<]>.>>[
+        [-]<[>+<-]>>[<<+>+>-]<[>+<-[>+<-[>+<-[>+<-[>+<-[>+<-
+            [>+<-[>+<-[>+<-[>[-]>+>+<<<-[>+<-]]]]]]]]]]]+>>>
+    ]<<<
+]";
+  var pos = 0;
+  var len = #src;
+  var char;
+  var depth = 0;
+
+  // input
+  var input = "";
+  var inppos = 0;
+
+  // tape
+  var tape = @[];
+  var ptr = 0;
+  var ptrmax = 30000 - 1;
+
+
+
+  var i = 0;
+  while (i < ptrmax) {
+    tape[i] = 0;
+    i = i + 1;
+  };
+
+  { @mainloop
+    while (pos < len) {
+      char = src[pos];
+
+      if (char == "<")
+        if (ptr > 0)
+          ptr = ptr - 1
+        else
+          ptr = ptrmax
+      ;
+
+      if (char == ">")
+        if (ptr < ptrmax)
+          ptr = ptr + 1
+        else
+          ptr = 0
+      ;
+
+      if (char == "+")
+        if (tape[ptr] < 255)
+          tape[ptr] = tape[ptr] + 1
+        else
+          tape[ptr] = 0
+      ;
+
+      if (char == "-")
+        if (tape[ptr] > 0)
+          tape[ptr] = tape[ptr] - 1
+        else
+          tape[ptr] = 255
+      ;
+
+      if (char == ".")
+        print(chr(tape[ptr]))
+      ;
+
+      if (char == ",") {
+        tape[ptr] = int(input[inppos]);
+        inppos = inppos + 1;
+      };
+
+      if (char == "[") {
+        if (tape[ptr] == 0) {
+          depth = depth + 1;
+          while (depth > 0) {
+            pos = pos + 1;
+            char = src[pos];
+            depth = depth + 
+              if (char == "[")
+                1
+              else if (char == "]")
+                -1
+              else
+                0
+            ;
+          };
+        };
+      };
+
+      if (char == "]") {
+        if (tape[ptr] != 0) {
+          depth = depth + 1;
+          while (depth > 0) {
+            pos = pos - 1;
+            char = src[pos];
+            depth = depth +
+              if (char == "]")
+                1
+              else if (char == "[")
+                -1
+              else
+                0
+            ;
+          };
+        };
+      };
+        
+      pos = pos + 1;
+    };
+  };
+
+};

src/ndspkg/chunk.nim

@@ -7,7 +7,7 @@ type
   OpCode* = enum
     opReturn, opCall, opCheckArity, opFunctionDef, # functions
     opPop, opPopSA, opPopA # pop
-    opPrint, # print
+    opPrint, # print TODO move to native func
     opNegate, opNot # unary
     opAdd, opSubtract, opMultiply, opDivide, # math
     opEqual, opGreater, opLess, # comparison
@@ -18,6 +18,7 @@ type
     opJumpIfFalse, opJump, opLoop, opJumpIfFalsePop, # jumps
     opCreateList, opCreateTable, # collection creation
     opLen, opSetIndex, opGetIndex, # collection operators
+    opChr, opInt, # temporary opcodes for the brainfuck interpreter TODO move to native funcs
 
   Chunk* = object
     code*: seq[uint8]
@@ -82,6 +83,7 @@ const simpleInstructions = {
   opEqual, opGreater, opLess,
   opTrue, opFalse, opNil,
   opLen, opSetIndex, opGetIndex,
+  opChr, opInt,
 }
 const constantInstructions = {
   opConstant,

src/ndspkg/compiler.nim

@@ -469,10 +469,16 @@ proc unary(comp: Compiler) =
       comp.writeChunk(0, opNegate)
     of tkBang:
       comp.writeChunk(0, opNot)
+    of tkInt:
+      comp.writeChunk(0, opInt)
+    of tkChr:
+      comp.writeChunk(0, opChr)
     else:
       discard # unreachable
 
 tkBang.genRule(unary, nop, pcNone)
+tkInt.genRule(unary, nop, pcNone)
+tkChr.genRule(unary, nop, pcNone)
 
 proc binary(comp: Compiler) =
   let opType = comp.previous.tokenType

src/ndspkg/scanner.nim

@@ -19,6 +19,7 @@ type
     tkIdentifier, tkString,
     tkNumber, tkAnd, tkElse, tkFalse, tkFor, tkFunct, tkGoto, tkIf, tkNil,
     tkOr, tkPrint, tkLabel, tkBreak, tkTrue, tkVar, tkWhile,
+    tkChr, tkInt,
     tkError, tkEof
 
   Token* = object
@@ -124,7 +125,9 @@ const keywords = {
   "print": tkPrint,
   "true": tkTrue,
   "var": tkVar,
-  "while": tkWhile
+  "while": tkWhile,
+  "int": tkInt,
+  "chr": tkChr,
 }.toTable
 
 proc canStartIdent(chr: char): bool =

src/ndspkg/vm.nim

@@ -157,7 +157,7 @@ proc run*(chunk: Chunk): InterpretResult =
           runtimeError(res.msg)
           break
       of opPrint:
-        echo $stack.peek()
+        write stdout, $stack.peek()
       of opDefineGlobal:
         let name = readConstant().asString()
         let existed = globals.tableSet(name.fromNdString(), stack.pop())
@@ -264,7 +264,20 @@ proc run*(chunk: Chunk): InterpretResult =
         if not res.ok:
           runtimeError(res.msg)
           break
-
+      of opChr:
+        let val = stack.pop()
+        if not val.isFloat() or val.asFloat() > 255f or val.asFloat() < 0f:
+          runtimeError("chr on not float or float out of range")
+          break
+        let chr = val.asFloat().int().char()
+        stack.push(($chr).fromNimString())
+      of opInt:
+        let val = stack.pop()
+        if not val.isString():
+          runtimeError("int on non string")
+          break
+        let code = ($val.asString())[0].int().float()
+        stack.push(code.fromFloat())
 
     when profileInstructions:
       durations[ins] += getMonoTime() - startTime