Working

git-svn-id: svn://svn.cc65.org/cc65/trunk@1212 b7a2c559-68d2-44c3-8de9-860c34a00d81

src/sim65/memory.c

@@ -33,23 +33,90 @@
 
 
 
+/* common */
+#include "coll.h"
+
 /* sim65 */
 #include "memory.h"
 
 
 
 /*****************************************************************************/
-/*  				     Data				     */
+/*                                   Forwards                                */
 /*****************************************************************************/
 
 
 
-static unsigned char RAM[0x10000];
+static void MemWrite (unsigned Addr, unsigned char Val);
+/* Write one byte to the memory cell */
+
+static unsigned char MemRead (unsigned Attr);
+/* Read one memory cell */
 
 
 
 /*****************************************************************************/
-/*  				     Code				     */
+/*  			    	     Data				     */
+/*****************************************************************************/
+
+
+
+/* RAM attributes */
+#define RA_READFUNC_MASK        0x000F  /* Up to 16 read functions */
+#define RA_WRITEFUNC_MASK       0x00F0  /* Up to 16 write functions */
+#define RA_INITIALIZED          0x0100  /* Memory cell is initialized */
+#define RA_WPROT                0x0200  /* Memory cell is write protected */
+
+/* Defines reader and writer functions */
+#define RA_READFUNC_SHIFT       0
+#define RA_WRITEFUNC_SHIFT      4
+#define RA_READFUNC_MAX         16
+#define RA_WRITEFUNC_MAX        16
+
+/* Read/write function declarations */
+typedef unsigned char (*ReadFunc) (unsigned Addr);
+typedef void (*WriteFunc) (unsigned Addr, unsigned char Val);
+static Collection ReadFuncs  = STATIC_COLLECTION_INITIALIZER;
+static Collection WriteFuncs = STATIC_COLLECTION_INITIALIZER;
+
+/* Memory attributes and the memory */
+static unsigned short MemAttr[0x10000];
+static unsigned char Mem[0x10000];
+
+
+
+/*****************************************************************************/
+/*                              Internal functions                           */
+/*****************************************************************************/
+
+
+
+static void MemWrite (unsigned Addr, unsigned char Val)
+/* Write one byte to the memory cell */
+{
+    if (MemAttr[Addr] & RA_WPROT) {
+        /* ### */
+    }
+    Mem[Addr] = Val;
+    MemAttr[Addr] |= RA_INITIALIZED;
+}
+
+
+
+static unsigned char MemRead (unsigned Addr)
+/* Read one memory cell */
+{
+    if ((MemAttr[Addr] & RA_INITIALIZED) == 0) {
+        /* We're reading a memory cell that was never written */
+        /* ### */
+    }
+    return Mem[Addr];
+}
+
+
+
+/*****************************************************************************/
+/*   				     Code				     */
 /*****************************************************************************/
 
 
@@ -57,7 +124,12 @@ static unsigned char RAM[0x10000];
 void MemWriteByte (unsigned Addr, unsigned char Val)
 /* Write a byte to a memory location */
 {
-    RAM[Addr] = Val;
+    /* Get the writer function */
+    unsigned  WI = (MemAttr[Addr] & RA_WRITEFUNC_MASK) >> RA_WRITEFUNC_SHIFT;
+    WriteFunc WF = CollAt (&WriteFuncs, WI);
+
+    /* Call the writer function */
+    WF (Addr, Val);
 }
 
 
@@ -65,7 +137,12 @@ void MemWriteByte (unsigned Addr, unsigned char Val)
 unsigned char MemReadByte (unsigned Addr)
 /* Read a byte from a memory location */
 {
-    return RAM[Addr];
+    /* Get the reader function */
+    unsigned  RI = (MemAttr[Addr] & RA_READFUNC_MASK) >> RA_READFUNC_SHIFT;
+    ReadFunc RF = CollAt (&WriteFuncs, RI);
+
+    /* Call the reader function */
+    return RF (Addr);
 }
 
 
@@ -91,3 +168,23 @@ unsigned MemReadZPWord (unsigned char Addr)
 
 
 
+void MemInit (void)
+/* Initialize the memory subsystem */
+{
+    unsigned I;
+
+    /* Clear the memory and it's attributes. Writing zeroes to the
+     * attribute array will cause any special flags to be reset and
+     * the default read and write functions to be used.
+     */
+    for (I = 0; I < sizeof (Mem) / sizeof (Mem[0]); ++I) {
+        Mem[I] = 0;
+    }
+    for (I = 0; I < sizeof (MemAttr) / sizeof (MemAttr[0]); ++I) {
+        MemAttr[I] = 0;
+    }
+
+    /* Add the default reader and writer functions to the collection */
+    CollAppend (&ReadFuncs, MemRead);
+    CollAppend (&WriteFuncs, MemWrite);
+}