strlen

Nub.Lang/Nub.Lang/Generation/Generator.cs

@@ -66,6 +66,26 @@ public class Generator
             _builder.AppendLine();
             GenerateFuncDefinition(funcDefinition);
         }
+
+        _builder.AppendLine("""
+                            
+                            ; https://tuttlem.github.io/2013/01/08/strlen-implementation-in-nasm.html
+                            strlen:
+                                push rcx            ; save and clear out counter
+                                xor rcx, rcx
+                            .strlen_next:
+                                cmp [rdi], byte 0   ; null byte yet?
+                                jz .strlen_null     ; yes, get out
+                                inc rcx             ; char is ok, count it
+                                inc rdi             ; move to next char
+                                jmp .strlen_next    ; process again
+                            .strlen_null:
+                                mov rax, rcx        ; rcx = the length (put in rax)
+                                pop rcx             ; restore rcx
+                                ret                 ; get out
+                            """);
+        
+        
         _builder.AppendLine();
         _builder.AppendLine("section .data");
         foreach (var str in _strings)
@@ -148,6 +168,9 @@ public class Generator
             case LiteralNode literal:
                 GenerateLiteral(literal, func);
                 break;
+            case StrlenNode strlen:
+                GenerateStrlen(strlen, func);
+                break;
             case SyscallExpressionNode syscallExpression:
                 throw new NotImplementedException();
                 break;
@@ -232,6 +255,13 @@ public class Generator
         }
     }
 
+    private void GenerateStrlen(StrlenNode strlen, Func func)
+    {
+        GenerateExpression(strlen.String, func);
+        _builder.AppendLine("    mov rdi, rax");
+        _builder.AppendLine("    call strlen");
+    }
+
     // TODO: Use stack for more than 6 parameters
     private void GenerateFuncCall(FuncCall funcCall, Func func)
     {

Nub.Lang/Nub.Lang/Input/program.nub

@@ -7,6 +7,6 @@ func main() {
     write("test\n");
 }
 
-func write(msg: pointer) {
+func write(msg: String) {
-    syscall(SYS_WRITE, STD_OUT, msg, 5);
+    syscall(SYS_WRITE, STD_OUT, msg, strlen(msg));
 }

Nub.Lang/Nub.Lang/Parsing/Parser.cs

@@ -144,7 +144,12 @@ public class Parser
             {
                 return new SyscallExpressionNode(new Syscall(parameters));
             }
-            
+
+            if (identifier.Value == "strlen" && parameters.Count == 1)
+            {
+                return new StrlenNode(parameters[0]);
+            }
+
             return new FuncCallExpressionNode(new FuncCall(identifier.Value, parameters));
         }
         
@@ -184,7 +189,7 @@ public class Parser
             return new DelegateType(typeArguments.Take(typeArguments.Count - 1).ToList(), returnType);
         }
 
-        if (name == "pointer")
+        if (name == "String")
         {
             return new StringType();
         }

Nub.Lang/Nub.Lang/Parsing/StrlenNode.cs

@@ -0,0 +1,6 @@
+namespace Nub.Lang.Parsing;
+
+public class StrlenNode(ExpressionNode @string) : ExpressionNode
+{
+    public ExpressionNode String { get; } = @string;
+}

Nub.Lang/Nub.Lang/Type.cs

@@ -56,7 +56,7 @@ public enum PrimitiveTypeKind
 
 public record StringType : Type
 {
-    public override string ToString() => "string";
+    public override string ToString() => "String";
 }
 
 public record DelegateType : Type

Nub.Lang/Nub.Lang/Typing/ExpressionTyper.cs

@@ -104,6 +104,9 @@ public class ExpressionTyper
             case LiteralNode literal:
                 PopulateLiteral(literal);
                 break;
+            case StrlenNode strlen:
+                PopulateStrlen(strlen);
+                break;
             case SyscallExpressionNode syscall:
                 PopulateSyscallExpression(syscall);
                 break;
@@ -146,6 +149,11 @@ public class ExpressionTyper
         literal.Type = literal.LiteralType;
     }
 
+    private static void PopulateStrlen(StrlenNode strlen)
+    {
+        strlen.Type = new PrimitiveType(PrimitiveTypeKind.Int64);
+    }
+
     private void PopulateSyscallExpression(SyscallExpressionNode syscall)
     {
         foreach (var parameter in syscall.Syscall.Parameters)