From c21e2b1ce33eb3fb3269a91efe05aa5de39d3165 Mon Sep 17 00:00:00 2001
From: Tiago Gasiba <tiago.gasiba@siemens.com>
Date: Thu, 18 Aug 2016 17:29:33 +0200
Subject: [PATCH] towards function calling with ret val

---
 cucu.c           | 52 ++++++++++++++++++++++++++++++------------------
 gen-zpu/gen.c    | 25 ++++++++++++++++-------
 tests/test_001.c | 11 ++++++++--
 3 files changed, 60 insertions(+), 28 deletions(-)

diff --git a/cucu.c b/cucu.c
index 9cfec32..111f757 100644
--- a/cucu.c
+++ b/cucu.c
@@ -5,6 +5,8 @@
 #include <ctype.h>
 #include <string.h>
 
+#define MAXTOKSZ 256
+
 /* print fatal error message and exit */
 static void error(const char *fmt, ...) {
   va_list args;
@@ -14,10 +16,24 @@ static void error(const char *fmt, ...) {
   exit(1);
 }
 
-/*
- * LEXER
- */
-#define MAXTOKSZ 256
+//
+// SYMBOLS
+//
+#define MAXSYMBOLS 4096
+static struct sym {
+  char type;
+  int  addr;
+  char name[MAXTOKSZ];
+  int  nParams;
+} sym[MAXSYMBOLS];
+
+static int sympos = 0;
+int stack_pos = 0;
+
+
+//
+// LEXER
+//
 static FILE *f;            /* input source file */
 static char tok[MAXTOKSZ]; /* current token */
 static int tokpos;         /* offset inside the current token */
@@ -30,6 +46,7 @@ static int numPreambleVars = 0;
 static int numGlobalVars = 0;
 static int lastIsReturn = 0;
 static int flagScanGlobalVars = 1;
+static struct sym *currFunction = NULL;
 
 /* read next char */
 void readchr() {
@@ -134,22 +151,10 @@ void expect(int srclinenum, char *s) {
   }
 }
 
-/*
- * SYMBOLS
- */
-#define MAXSYMBOLS 4096
-static struct sym {
-  char type;
-  int  addr;
-  char name[MAXTOKSZ];
-} sym[MAXSYMBOLS];
-static int sympos = 0;
-
-int stack_pos = 0;
-
 static struct sym *sym_find(char *s) {
   int i;
   struct sym *symbol = NULL;
+  
   for (i = 0; i < sympos; i++) {
     if (strcmp(sym[i].name, s) == 0) {
       symbol = &sym[i];
@@ -202,7 +207,7 @@ static void emit(void *buf, size_t len) {
   codepos += len;
 }
 
-#define TYPE_NUM  0
+#define TYPE_NUM     0
 #define TYPE_CHARVAR 1
 #define TYPE_INTVAR  2
 
@@ -355,6 +360,11 @@ static int postfix_expr() {
     gen_stack_addr(stack_pos - call_addr - 1);
     gen_unref(TYPE_INTVAR);
     gen_call();
+    if (currFunction) {
+      gen_call_cleanup(currFunction->nParams);
+    } else {
+        error("[line %d] Error: unexpected function exit\n",linenum);
+    }
     /* remove function address and args */
     gen_pop(stack_pos - prev_stack_pos);
     stack_pos = prev_stack_pos;
@@ -433,6 +443,7 @@ static int expr() {
   int type = bitwise_expr();
   if (type != TYPE_NUM) {
     if (accept("=")) {
+      printf("HERE 1=\n");
       gen_push(); expr(); 
       if (type == TYPE_INTVAR) {
         emit(GEN_ASSIGN, GEN_ASSIGNSZ);
@@ -467,6 +478,7 @@ static void statement() {
     printf("GENERATE_VAR %s_%s\n",context,tok);
     readtok();
     if (accept("=")) {
+      printf("HERE 2=\n");
       expr();
     }
     numPreambleVars++;
@@ -574,11 +586,13 @@ static void compile() {
       stack_pos = 0;
       var->addr = codepos;
       var->type = 'F';
+      var->nParams = argc;
       gen_sym(var);
-      printf("FUNCTION: %s\n",var->name);
+      printf("FUNCTION: %s with %d params\n",var->name, argc);
       strcpy(context,var->name);
       genPreamble = 1;
       numPreambleVars = 0;
+      currFunction = var;
       statement(); // function body
       if (!lastIsReturn) {
         gen_ret(numPreambleVars);   // issue a ret if user forgets to put 'return'
diff --git a/gen-zpu/gen.c b/gen-zpu/gen.c
index 9dbfa55..461b451 100644
--- a/gen-zpu/gen.c
+++ b/gen-zpu/gen.c
@@ -49,17 +49,23 @@ static int mem_pos = 0;
 #define GEN_JZSZ strlen(GEN_JZ)
 
 
-  struct _imm_struct {
-    int nImm;
-    int v[5];
-  };
+struct _imm_struct {
+  int nImm;
+  int v[5];
+};
+
+int fixme_offset = 0;
+int addrCnt = 0;
 
 static struct _imm_struct _load_immediate( int32_t v );
 
 static void gen_start(int nGlobalVars) {
   char buf[100];
-  sprintf(buf,"GLOBALS %d\n",nGlobalVars);
-  emits("jmpCAFE\n");
+  sprintf(buf,"GLOBALS %d\n", nGlobalVars);
+  strcat(buf,"---\n");
+  fixme_offset = strlen(buf) + 1 + 3;
+  strcat(buf,"JMP xxxx\n");
+  strcat(buf,"---\n");
   emits(buf);
 }
 
@@ -70,7 +76,7 @@ static void gen_finish() {
     error("ERROR: could not find main function\n");
   }
   sprintf(s, "%04x", funcmain->addr);
-  memcpy(code+3, s, 4);
+  memcpy(code+fixme_offset, s, 4);
   printf("%s", code);
 }
 
@@ -90,6 +96,11 @@ static void gen_postamble(int nVars) {
   stack_pos = stack_pos + 1;
 }
 
+static void gen_call_cleanup(int nVars) {
+  char buf[100];
+  sprintf(buf,"DO CLEAN %d\n",nVars);
+  emits(buf);
+}
 
 static void gen_ret(int nVars) {
   gen_postamble(nVars);
diff --git a/tests/test_001.c b/tests/test_001.c
index f45d7e4..03f04da 100644
--- a/tests/test_001.c
+++ b/tests/test_001.c
@@ -1,10 +1,17 @@
 int g_a;
 
-int main( int c0, int c1 ) {
+int func( int a ) {
+  g_a = 1;
+}
+
+//int main( int c0, int c1, int c2, int c3 ) {
+int main( void ) {
   int a;
   int b;
 //  a = 0x4f;
-//  func(0x44);
+  func(0x44);
+  a = func(0x44);
+  a = 1 + func(2+0x44);
   return 0;
 }