From 2b655476c079f05d686f42b507bfef52d951c26f Mon Sep 17 00:00:00 2001
From: Jeremiah Orians <jeremiah@pdp10.guru>
Date: Sat, 1 Oct 2016 20:50:06 -0400
Subject: [PATCH] Made Setexpression iterative rather than recursive

---
 High_level_prototypes/M0-macro.c | 12 +++++++-----
 stage1/M0-macro.s                | 27 +++++++++++++++------------
 2 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/High_level_prototypes/M0-macro.c b/High_level_prototypes/M0-macro.c
index 27521c4..b868576 100644
--- a/High_level_prototypes/M0-macro.c
+++ b/High_level_prototypes/M0-macro.c
@@ -133,14 +133,10 @@ struct Token* Tokenize_Line(struct Token* head)
 
 void setExpression(struct Token* p, char match[], char Exp[])
 {
-	if(NULL != p->next)
-	{
-		setExpression(p->next, match, Exp);
-	}
-
 	/* Leave macros alone */
 	if((p->type & macro))
 	{
+		setExpression(p->next, match, Exp);
 		return;
 	}
 
@@ -149,6 +145,12 @@ void setExpression(struct Token* p, char match[], char Exp[])
 	{
 		p->Expression = Exp;
 	}
+
+	if(NULL != p->next)
+	{
+		setExpression(p->next, match, Exp);
+	}
+
 }
 
 void identify_macros(struct Token* p)
diff --git a/stage1/M0-macro.s b/stage1/M0-macro.s
index 9b09461..647771c 100644
--- a/stage1/M0-macro.s
+++ b/stage1/M0-macro.s
@@ -415,25 +415,28 @@
 	;; Preserve registers
 	PUSHR R0 R15
 	PUSHR R3 R15
+	PUSHR R4 R15
 
-	LOAD32 R3 R0 0              ; Load Next
-	SWAP R0 R3                  ; Protect R0
-	CMPSKIP.E R0 0              ; if Next is Null
-	CALLI R15 @setExpression    ; Don't recurse
-	MOVE R0 R3                  ; Restore R0
+	;; Initialize
+	MOVE R4 R1                  ; Put Macro Text in a safe place
+:setExpression_0
 	LOAD32 R3 R0 4              ; Load type into R3
-	CMPSKIP.NE R3 1             ; If Node is a macro
-	JUMP @setExpression_Done    ; Be done
-	LOAD32 R3 R0 8              ; Load Text into R3
-	SWAP R0 R3                  ; Prepare for strncmp
+	CMPSKIP.NE R3 1             ; Check if Macro
+	JUMP @setExpression_1       ; Move to next if Macro
+	MOVE R3 R0                  ; Preserve node Pointer
+	LOAD32 R0 R3 8              ; Load Text pointer into R0 for Comparision
+	COPY R1 R4                  ; Put Macro Text for comparision
 	CALLI R15 @strcmp           ; compare Text and Macro Text
-	JUMP.NE R0 @setExpression_Done
-
-	;; Node matches
+	JUMP.NE R0 @setExpression_1 ; Move to next if not Match
 	STORE32 R2 R3 12            ; Set node->Expression = Exp
 
+:setExpression_1
+	LOAD32 R0 R3 0              ; Load Next
+	JUMP.NZ R0 @setExpression_0 ; Loop if next isn't NULL
+
 :setExpression_Done
 	;; Restore registers
+	POPR R4 R15
 	POPR R3 R15
 	POPR R0 R15
 	RET R15