From 10d436107cce369a7351c8ffccb273a2965b36d9 Mon Sep 17 00:00:00 2001
From: r4 <r4@nobrain.org>
Date: Tue, 21 Dec 2021 15:02:53 +0100
Subject: [PATCH] very basic while loop

---
 example.script | 17 +++------------
 ir.c           |  6 ++---
 parse.c        | 59 +++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 64 insertions(+), 18 deletions(-)

diff --git a/example.script b/example.script
index 9465ac7..af78fb1 100644
--- a/example.script
+++ b/example.script
@@ -1,15 +1,4 @@
-a := 0
-{
-	a := 1
-	b := a
-}
-
-//a := 1
-//b := 1 - 2 * 2 + 5
-//c := a + b * 2 * b
-//d := a + 4 * b * a
-
-/*x := 1
+x := 1
 y := 1
 
 i := 60
@@ -17,6 +6,6 @@ while i {
 	z := x + y
 	y = x
 	x = z
-	print(z)
+	//print(z)
 	i = i - 1
-}*/
+}
diff --git a/ir.c b/ir.c
index a6dc956..d7ef498 100644
--- a/ir.c
+++ b/ir.c
@@ -69,6 +69,7 @@ static void print_irparam(const IRParam *p) {
 
 void print_ir(IRToks *v) {
 	for (size_t i = 0; i < v->len; i++) {
+		printf("%04zx ", i);
 		printf("%s", irinstr_str[v->toks[i].instr]);
 		switch (v->toks[i].instr) {
 			case IRSet:
@@ -92,13 +93,12 @@ void print_ir(IRToks *v) {
 				}
 				break;
 			case IRJmp:
-				printf(" ");
-				printf(" %zu", v->toks[i].Jmp.iaddr);
+				printf(" %zx", v->toks[i].Jmp.iaddr);
 				break;
 			case IRJnz:
 				printf(" ");
 				print_irparam(&v->toks[i].CJmp.condition);
-				printf(" %zu", v->toks[i].CJmp.iaddr);
+				printf(" %zx", v->toks[i].CJmp.iaddr);
 				break;
 			default:
 				break;
diff --git a/parse.c b/parse.c
index 8cc8a1e..1f26259 100644
--- a/parse.c
+++ b/parse.c
@@ -356,9 +356,66 @@ static void stmt(State *s, Scope *sc, TokListItem *t) {
 				if (t->next->tok.Op == OpRCurl)
 					break;
 			}
-			TRY(stmt(s, &inner_sc, t->next));
+			TRY_ELSE(stmt(s, &inner_sc, t->next), term_scope(&inner_sc));
 		}
 		term_scope(&inner_sc);
+		t = t->next;
+	} else if (t->tok.kind == TokWhile) {
+		/* How while is generally implemented in IR: 
+		 * 0: jmp to 3
+		 * 1: some_code
+		 * 2: some_code
+		 * 3: some stuff evaluating condition xyz
+		 * 4: jmp to 1 if condition xyz is met
+		 * */
+
+		size_t jmp_instr_iaddr = s->ir->len;
+		irtoks_app(s->ir, (IRTok){
+			.ln = t->tok.ln,
+			.col = t->tok.col,
+			.instr = IRJmp,
+			.Jmp = {
+				.iaddr = 0, /* unknown for now */
+			},
+		});
+
+		t = t->next;
+
+		/* find beginning of while loop body */
+		TokListItem *lcurl;
+		for (TokListItem *i = t;; i++) {
+			if (i == NULL) {
+				mark_err(&start->tok);
+				set_err("Expected '{' after 'while' loop condition");
+				return;
+			}
+			if (i->tok.kind == TokOp && i->tok.Op == OpLCurl) {
+				lcurl = i;
+				break;
+			}
+		}
+
+		/* write loop body to IR stream */
+		TRY(stmt(s, sc, lcurl));
+
+		/* finally we know where the jmp from the beginning has to jump to */
+		s->ir->toks[jmp_instr_iaddr].Jmp.iaddr = s->ir->len;
+
+		size_t addr = sc->mem_addr++;
+		TRY(expr(s, sc, t, true, true, addr));
+
+		irtoks_app(s->ir, (IRTok){
+			.ln = t->tok.ln,
+			.col = t->tok.col,
+			.instr = IRJnz,
+			.CJmp = {
+				.iaddr = jmp_instr_iaddr + 1,
+				.condition = {
+					.kind = IRParamAddr,
+					.Addr = addr,
+				},
+			},
+		});
 	}
 	toklist_del(s->toks, start, t);
 }