[Inform mntce] Glulx memory-extension patch

[Andrew Plotkin]

Glulx has a very simple memory-extension feature, where you declare the 
memory map to be larger than the game file. The extra space is filled 
out with zeroes when the game starts.

This has been in the spec since the beginning, and interpreters support it 
(as far as I know!) but I6 doesn't. This is the I6 patch to support it. It 
defines a new memory option, $MEMORY_MAP_EXTENSION.

I don't expect this to be of immediate use to I7 or to anybody else -- you 
can already accomplish nearly the same thing by calling @setmemsize at 
startup time. But I want to test the feature, so I need to be able to 
compile it.

--Z

-- 
"And Aholibamah bare Jeush, and Jaalam, and Korah: these were the borogoves..."
*
-------------- next part --------------
diff --git a/files.c b/files.c
index 9b2f532..5a13b49 100644
--- a/files.c
+++ b/files.c
@@ -553,11 +553,12 @@ game features require version 0x%08lx", requested_glulx_version, VersionNum);
     sf_put((Out_Size >> 16));
     sf_put((Out_Size >> 8));
     sf_put((Out_Size));
-    /* ENDMEM, which is also game file size */
-    sf_put((Out_Size >> 24));
-    sf_put((Out_Size >> 16));
-    sf_put((Out_Size >> 8));
-    sf_put((Out_Size));
+    /* ENDMEM, which the game file size plus MEMORY_MAP_EXTENSION */
+    i = Out_Size + MEMORY_MAP_EXTENSION;
+    sf_put((i >> 24));
+    sf_put((i >> 16));
+    sf_put((i >> 8));
+    sf_put((i));
     /* STACKSIZE */
     sf_put((MAX_STACK_SIZE >> 24));
     sf_put((MAX_STACK_SIZE >> 16));
diff --git a/header.h b/header.h
index 28ca1d1..7358e33 100644
--- a/header.h
+++ b/header.h
@@ -2409,7 +2409,7 @@ extern int MAX_QTEXT_SIZE,  MAX_SYMBOLS,    HASH_TAB_SIZE,   MAX_DICT_ENTRIES,
 extern int32 MAX_STATIC_STRINGS, MAX_ZCODE_SIZE, MAX_LINK_DATA_SIZE,
            MAX_TRANSCRIPT_SIZE,  MAX_INDIV_PROP_TABLE_SIZE,
            MAX_NUM_STATIC_STRINGS, MAX_UNICODE_CHARS,
-           MAX_STACK_SIZE;
+           MAX_STACK_SIZE, MEMORY_MAP_EXTENSION;
 
 extern int32 MAX_OBJ_PROP_COUNT, MAX_OBJ_PROP_TABLE_SIZE;
 extern int MAX_LOCAL_VARIABLES, MAX_GLOBAL_VARIABLES;
diff --git a/memory.c b/memory.c
index a94f98b..1ec8baa 100644
--- a/memory.c
+++ b/memory.c
@@ -176,6 +176,7 @@ int NUM_ATTR_BYTES;
 int32 MAX_NUM_STATIC_STRINGS;
 int32 MAX_UNICODE_CHARS;
 int32 MAX_STACK_SIZE;
+int32 MEMORY_MAP_EXTENSION;
 int ALLOC_CHUNK_SIZE;
 
 /* The way memory sizes are set causes great nuisance for those parameters
@@ -220,6 +221,9 @@ static void list_memory_sizes(void)
       printf("|  %25s = %-7d |\n","MAX_LOCAL_VARIABLES",MAX_LOCAL_VARIABLES);
     printf("|  %25s = %-7d |\n","MAX_LOW_STRINGS",MAX_LOW_STRINGS);
     if (glulx_mode)
+      printf("|  %25s = %-7d |\n","MEMORY_MAP_EXTENSION",
+        MEMORY_MAP_EXTENSION);
+    if (glulx_mode)
       printf("|  %25s = %-7d |\n","MAX_NUM_STATIC_STRINGS",
         MAX_NUM_STATIC_STRINGS);
     printf("|  %25s = %-7d |\n","MAX_OBJECTS",MAX_OBJECTS);
@@ -418,6 +422,7 @@ extern void set_memory_sizes(int size_flag)
     NUM_ATTR_BYTES_z = 6;
     NUM_ATTR_BYTES_g = 7;
     MAX_UNICODE_CHARS = 64;
+    MEMORY_MAP_EXTENSION = 0;
     /* We estimate the default Glulx stack size at 4096. That's about
        enough for 90 nested function calls with 8 locals each -- the
        same capacity as the Z-Spec's suggestion for Z-machine stack
@@ -700,6 +705,13 @@ static void explain_parameter(char *command)
   during gameplay. (Glulx only)\n");
         return;
     }
+    if (strcmp(command,"MEMORY_MAP_EXTENSION")==0)
+    {
+        printf(
+"  MEMORY_MAP_EXTENSION is the number of bytes (all zeroes) to map into \n\
+  memory after the game file. (Glulx only)\n");
+        return;
+    }
 
     printf("No such memory setting as \"%s\"\n",command);
 
@@ -845,6 +857,12 @@ extern void memory_command(char *command)
                 /* Adjust up to a 256-byte boundary. */
                 MAX_STACK_SIZE = (MAX_STACK_SIZE + 0xFF) & (~0xFF);
             }
+            if (strcmp(command,"MEMORY_MAP_EXTENSION")==0)
+            {
+                MEMORY_MAP_EXTENSION=j, flag=1;
+                /* Adjust up to a 256-byte boundary. */
+                MEMORY_MAP_EXTENSION = (MEMORY_MAP_EXTENSION + 0xFF) & (~0xFF);
+            }
 
             if (flag==0)
                 printf("No such memory setting as \"%s\"\n", command);