get functions and arguments and returning to work fully

5 files changed, 62 insertions, 35 deletions

diff --git a/Makefile b/Makefile
index fcb0c82..e81ea76 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 CS=ast.c         com.c dis.c ht.c mem.c prs.c read.c state.c        val.c vm.c
 HS=ast.h chunk.h com.h dis.h ht.h mem.h prs.h read.h state.h util.h val.h vm.h
-CFLAGS=$(EXTRA_CFLAGS) -O3 -lm -Wall -Wpedantic -Werror=implicit-function-declaration
+CFLAGS=$(EXTRA_CFLAGS) -g -O3 -lm -Wall -Wpedantic -Werror=implicit-function-declaration
 
 bth: $(CS) $(HS) Makefile
 	$(CC) $(CFLAGS) -o bth $(CS)
diff --git a/com.c b/com.c
index b2f1f09..c5362cd 100644
--- a/com.c
+++ b/com.c
@@ -21,6 +21,7 @@ Compiler compiler_new(Compiler *outer, Chunk *ch) {
 		.S = outer->S,
 		.ch = ch,
 		.stack_cur = 0,
+		.scope = NULL,
 	};
 }
 
@@ -211,26 +212,6 @@ void arith_form(Compiler *C, AstVec l, Op op) {
 	compile_opcode(C, op);
 }
 
-void fn_form(Compiler *C, AstVec l, Op _) {
-	// (fn (arg arg arg) body ...)
-	CHECK(l.vals[1].ty == AST_LIST, "fn's first argument must be list");
-	AstVec arglist = l.vals[1].as.list;
-	CHECK(arglist.len <= 255, "maximum 255 args for function");
-	uint8_t arity = arglist.len;
-
-	ObjFunc *func = objfunc_new(C->S, arity);
-	Compiler subcompiler = compiler_new(C, &func->ch);
-
-	for (int i = 2; i < l.len - 1; i++) {
-		compile_node(&subcompiler, l.vals[i]);
-		compile_opcode(&subcompiler, OP_DROP);
-	}
-	compile_node(&subcompiler, l.vals[l.len-1]);
-	compile_opcode(&subcompiler, OP_RET);
-
-	compile_opcode(C, OP_LOADK);
-	compile_byte(C, compile_constant(C, VAL_OBJ(func)));
-}
 
 static void begin_scope(Compiler *C) {
 	Scope *sc = malloc(sizeof(Scope));
@@ -261,6 +242,7 @@ static void declare_local(Compiler *C, char *name) {
 	// -1 because local is expected to be already on the stack
 	// ie sitting just below where stack_cur points
 	l->slot = C->stack_cur - 1;
+	// printf("declaring local %s at %d, stack_cur is %d\n",l->name, l->slot, C->stack_cur);
 }
 
 void let_form(Compiler *C, AstVec l, Op _) {
@@ -286,7 +268,41 @@ void let_form(Compiler *C, AstVec l, Op _) {
 	end_scope(C);
 }
 
+void fn_form(Compiler *C, AstVec l, Op _) {
+	// (fn (arg arg arg) body ...)
+	CHECK(l.vals[1].ty == AST_LIST, "fn's first argument must be list");
+	AstVec arglist = l.vals[1].as.list;
+	CHECK(arglist.len <= 255, "maximum 255 args for function");
+	uint8_t arity = arglist.len;
+
+	ObjFunc *func = objfunc_new(C->S, arity);
+	Compiler subcompiler = compiler_new(C, &func->ch);
 
+	Compiler *SC = &subcompiler;
+	begin_scope(SC);
+	// when called, stack slot 0 contains the function itself,
+	// stack slots 1..n contain passed arguments
+	SC->stack_cur ++;
+	declare_local(SC, "__func__");
+	for (int i = 0; i < arity; i++) {
+		AstNode argname = arglist.vals[i];
+		CHECK(argname.ty == AST_IDENT, "argument name must be identifier");
+		SC->stack_cur ++;
+		declare_local(SC, argname.as.str);
+	}
+
+	for (int i = 2; i < l.len - 1; i++) {
+		compile_node(SC, l.vals[i]);
+		compile_opcode(SC, OP_DROP);
+	}
+	compile_node(&subcompiler, l.vals[l.len-1]);
+
+	end_scope(SC);
+	compile_opcode(SC, OP_RET);
+
+	compile_opcode(C, OP_LOADK);
+	compile_byte(C, compile_constant(C, VAL_OBJ(func)));
+}
 
 typedef struct {
 	char *name;
@@ -444,14 +460,13 @@ int main(int argc, char **argv) {
 
 	AstNode an = read();
 
-	Compiler com = (Compiler){
-		.S = S,
-		.ch = &ch,
-	};
+	Compiler com = (Compiler){ 0 };
+	com.S = S;
+	com.ch = &ch;
+
 	Compiler *C = &com;
 	compile_node(C, an);
 
-
 	compile_opcode(C, OP_PUTS);
 	compile_opcode(C, OP_HALT);
 
diff --git a/tests/vars2.bth b/tests/vars2.bth
index 3474d54..2d5ebd1 100644
--- a/tests/vars2.bth
+++ b/tests/vars2.bth
@@ -1,4 +1,4 @@
 (+ 2 (* 6 (let (a 10
-				b 20
-				c 30)
+                b 20
+                c 30)
                (* b b))))
diff --git a/vm.c b/vm.c
index b5b66d3..6084f21 100644
--- a/vm.c
+++ b/vm.c
@@ -36,14 +36,19 @@ int runvm(State *S) {
 #define RBYTE() (ch->bc.d[th->ip++])
 #define RSHORT() (th->ip += 2, (uint16_t)( ch->bc.d[th->ip-2] | ch->bc.d[th->ip-1] << 8 ))
 
-#define PUSH(v) th->stack[th->sp++] = v;
-#define POP()   (th->stack[--th->sp])
-#define PEEK()  (th->stack[th->sp-1])
+#define PUSH(v) th->stack[th->fp + th->sp++] = v;
+#define POP()   (th->stack[th->fp + --th->sp])
+#define PEEK()  (th->stack[th->fp + th->sp-1])
 
 	while (1) {
 		ch = th->ch;
 		if (S->do_trace) {
-			printf("%p ",(void *)ch);
+			printf("\t[%lu + %lu] : ",th->fp, th->sp);
+			for (int i = 0; i < th->sp; i++) {
+				print_val(th->stack[th->fp + i]);
+				printf(" ; ");
+			}
+			printf("\n%p ",(void *)ch);
 			disasm_instr(ch, th->ip);
 		}
 		uint8_t instr = RBYTE();
@@ -113,7 +118,7 @@ int runvm(State *S) {
 
 		case OP_GETLOCAL: {
 			uint8_t lidx = RBYTE();
-			PUSH(th->stack[lidx]);
+			PUSH(th->stack[th->fp + lidx]);
 			break;
 		}
 
@@ -164,9 +169,9 @@ int runvm(State *S) {
 
 		case OP_CALL: {
 			uint8_t len = RBYTE();
-			// ignore arguments for now
 			th->sp -= len-1;
 			Val callee = POP();
+
 			if (!IS_FUNC(callee)) {
 				fprintf(stderr, "can only call functions\n");
 				goto done;
@@ -176,9 +181,12 @@ int runvm(State *S) {
 			StackFrame *sf = &th->rstack[th->rsp++];
 			sf->ch = th->ch;
 			sf->ip = th->ip;
+			sf->fp = th->fp;
 
 			th->ch = &func->ch;
 			th->ip = 0;
+			th->fp = th->sp;
+			th->sp = len;
 			break;
 		}
 
@@ -192,8 +200,11 @@ int runvm(State *S) {
 
 		case OP_RET: {
 			StackFrame *sf = &th->rstack[--th->rsp]; 
+			size_t orig_fp = th->fp;
 			th->ch = sf->ch;
 			th->ip = sf->ip;
+			th->fp = sf->fp;
+			th->sp += (orig_fp - th->fp);
 			break;
 		}
 		case OP_HALT:
diff --git a/vm.h b/vm.h
index 0d1782d..39fc0bb 100644
--- a/vm.h
+++ b/vm.h
@@ -13,7 +13,7 @@ typedef struct _thread Thread;
 typedef struct {
 	size_t ip;
 	Chunk *ch;
-
+	size_t fp;
 } StackFrame;
 
 #define MAXDEPTH  64
@@ -22,6 +22,7 @@ typedef struct _thread {
 	Chunk *ch;
 	size_t ip;
 	Val stack[STACKSIZE];
+	size_t fp;
 	size_t sp;
 	StackFrame rstack[MAXDEPTH];
 	size_t rsp;