From b2396d3eda154923522bf1c24feb85259b35c149 Mon Sep 17 00:00:00 2001
From: "zik.saleeba" <zik.saleeba@21eae674-98b7-11dd-bd71-f92a316d2d60>
Date: Thu, 29 Jan 2009 11:10:46 +0000
Subject: [PATCH] Now stack frames appear on our new stack as they should. The
 old static limits are gone.

git-svn-id: http://picoc.googlecode.com/svn/trunk@40 21eae674-98b7-11dd-bd71-f92a316d2d60
---
 picoc.h    | 10 ++++------
 type.c     |  2 +-
 variable.c | 27 +++++++++++++--------------
 3 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/picoc.h b/picoc.h
index f7dbaef..ccc96a0 100644
--- a/picoc.h
+++ b/picoc.h
@@ -167,19 +167,17 @@ struct Table
 /* stack frame for function calls */
 struct StackFrame
 {
-    struct LexState ReturnLex;          /* how we got here */
-    struct Table LocalTable;            /* the local variables and parameters */
+    struct LexState ReturnLex;              /* how we got here */
+    struct Table LocalTable;                /* the local variables and parameters */
     struct TableEntry LocalHashTable[LOCAL_TABLE_SIZE];
+    struct StackFrame *PreviousStackFrame;  /* the next lower stack frame */
 };
 
 /* globals */
 extern struct Table GlobalTable;
-extern struct LexState FunctionStore[FUNCTION_STORE_MAX];
-extern int FunctionStoreUsed;
 extern struct Value *Parameter[PARAMETER_MAX];
 extern int ParameterUsed;
-extern struct StackFrame Stack[STACK_MAX];
-extern int StackUsed;
+extern struct StackFrame *TopStackFrame;
 extern struct Value *ReturnValue;
 extern struct ValueType IntType;
 extern struct ValueType CharType;
diff --git a/type.c b/type.c
index c3325dd..5cc904f 100644
--- a/type.c
+++ b/type.c
@@ -94,7 +94,7 @@ void TypeParseStruct(struct LexState *Lexer, struct ValueType **Typ, int IsStruc
     if (LexGetPlainToken(Lexer) != TokenLeftBrace)
         ProgramFail(Lexer, "'{' expected");
     
-    if (StackUsed != 0)
+    if (TopStackFrame != NULL)
         ProgramFail(Lexer, "struct/union definitions can only be globals");
         
     *Typ = TypeGetMatching(Lexer, &UberType, IsStruct ? TypeStruct : TypeUnion, 0, &LexValue->Val->String);
diff --git a/variable.c b/variable.c
index 752d8e6..feb36c4 100644
--- a/variable.c
+++ b/variable.c
@@ -7,14 +7,14 @@ struct Table GlobalTable;
 struct TableEntry GlobalHashTable[GLOBAL_TABLE_SIZE];
 
 /* the stack */
-struct StackFrame Stack[STACK_MAX];
-int StackUsed = 0;
+struct StackFrame *TopStackFrame = NULL;
 
 
 /* initialise the variable system */
 void VariableInit()
 {
     TableInit(&GlobalTable, &GlobalHashTable[0], GLOBAL_TABLE_SIZE);
+    TopStackFrame = NULL;
 }
 
 /* allocate some memory, either on the heap or the stack and check if we've run out */
@@ -64,7 +64,7 @@ struct Value *VariableAllocValueAndCopy(struct LexState *Lexer, struct Value *Fr
 /* define a variable */
 void VariableDefine(struct LexState *Lexer, const Str *Ident, struct Value *InitValue)
 {
-    if (!TableSet((StackUsed == 0) ? &GlobalTable : &Stack[StackUsed-1].LocalTable, Ident, VariableAllocValueAndCopy(Lexer, InitValue, StackUsed == 0)))
+    if (!TableSet((TopStackFrame == NULL) ? &GlobalTable : &TopStackFrame->LocalTable, Ident, VariableAllocValueAndCopy(Lexer, InitValue, TopStackFrame == NULL)))
         ProgramFail(Lexer, "'%S' is already defined", Ident);
 }
 
@@ -73,7 +73,7 @@ int VariableDefined(Str *Ident)
 {
     struct Value *FoundValue;
     
-    if (StackUsed == 0 || !TableGet(&Stack[StackUsed-1].LocalTable, Ident, &FoundValue))
+    if (TopStackFrame == NULL || !TableGet(&TopStackFrame->LocalTable, Ident, &FoundValue))
     {
         if (!TableGet(&GlobalTable, Ident, &FoundValue))
             return FALSE;
@@ -85,7 +85,7 @@ int VariableDefined(Str *Ident)
 /* get the value of a variable. must be defined */
 void VariableGet(struct LexState *Lexer, Str *Ident, struct Value **LVal)
 {
-    if (StackUsed == 0 || !TableGet(&Stack[StackUsed-1].LocalTable, Ident, LVal))
+    if (TopStackFrame == NULL || !TableGet(&TopStackFrame->LocalTable, Ident, LVal))
     {
         if (!TableGet(&GlobalTable, Ident, LVal))
             ProgramFail(Lexer, "'%S' is undefined", Ident);
@@ -114,24 +114,23 @@ void VariableStackPop(struct LexState *Lexer, struct Value *Var)
 /* add a stack frame when doing a function call */
 void VariableStackFrameAdd(struct LexState *Lexer)
 {
-    struct StackFrame *NewFrame = &Stack[StackUsed];
+    struct StackFrame *NewFrame;
     
-    if (StackUsed >= STACK_MAX)
-        ProgramFail(Lexer, "too many nested function calls");
-        
+    HeapPushStackFrame();
+    NewFrame = HeapAllocStack(sizeof(struct StackFrame));
     NewFrame->ReturnLex = *Lexer;
     TableInit(&NewFrame->LocalTable, &NewFrame->LocalHashTable[0], LOCAL_TABLE_SIZE);
-    StackUsed++;
-    HeapPushStackFrame();
+    NewFrame->PreviousStackFrame = TopStackFrame;
+    TopStackFrame = NewFrame;
 }
 
 /* remove a stack frame */
 void VariableStackFramePop(struct LexState *Lexer)
 {
-    if (StackUsed == 0)
+    if (TopStackFrame == NULL)
         ProgramFail(Lexer, "stack is empty - can't go back");
         
-    StackUsed--;
-    *Lexer = Stack[StackUsed].ReturnLex;
+    TopStackFrame = TopStackFrame->PreviousStackFrame;
+    *Lexer = TopStackFrame->ReturnLex;
     HeapPopStackFrame();
 }