shithub: choc

Download patch

ref: 53e98bc707cc0a37773985cfdce5419a7491da26
parent: fe9adcbd0b0e9b8e6ac744967bbf0ce3fcf40546
author: Simon Howard <fraggle@soulsphere.org>
date: Fri Jan 5 15:19:26 EST 2018 

hexen: Remove PCodePtr entirely.

Stop using pointers to represent code location; instead use an offset
from the start of the lump. This can be continually validated for
correctness and we exit with an error if we pass the end of the lump.


--- a/src/hexen/p_acs.c
+++ b/src/hexen/p_acs.c
@@ -55,7 +55,7 @@
 
 // PRIVATE FUNCTION PROTOTYPES ---------------------------------------------
 
-static void StartOpenACS(int number, int infoIndex, int *address);
+static void StartOpenACS(int number, int infoIndex, int offset);
 static void ScriptFinished(int number);
 static boolean TagBusy(int tag);
 static boolean AddToACSStore(int map, int number, byte * args);
@@ -185,7 +185,7 @@
 // PRIVATE DATA DEFINITIONS ------------------------------------------------
 
 static acs_t *ACScript;
-static int *PCodePtr;
+static unsigned int PCodeOffset;
 static byte SpecArgs[8];
 static int ACStringCount;
 static char **ACStrings;
@@ -344,6 +344,29 @@
 
 //==========================================================================
 //
+// ReadCodeInt
+//
+// Read a 32-bit value from the loaded ACS lump at the location pointed to
+// by PCodeOffset, advancing PCodeOffset to the next value in the process.
+//
+//==========================================================================
+
+static int ReadCodeInt(void)
+{
+    int result;
+    int *ptr;
+
+    ValidateLumpOffset(PCodeOffset + 3, "ReadCodeInt");
+
+    ptr = (int *) (ActionCodeBase + PCodeOffset);
+    result = LONG(*ptr);
+    PCodeOffset += 4;
+
+    return result;
+}
+
+//==========================================================================
+//
 // P_LoadACScripts
 //
 //==========================================================================
@@ -375,9 +398,7 @@
         info->number = LONG(*buffer);
         ++buffer;
 
-        info->address = (int *) (
-            (byte *) ActionCodeBase +
-            ValidateLumpOffset(LONG(*buffer), "script header"));
+        info->offset = ValidateLumpOffset(LONG(*buffer), "script header");
         ++buffer;
 
         info->argCount = LONG(*buffer);
@@ -396,7 +417,7 @@
         if (info->number >= OPEN_SCRIPTS_BASE)
         {                       // Auto-activate
             info->number -= OPEN_SCRIPTS_BASE;
-            StartOpenACS(info->number, i, info->address);
+            StartOpenACS(info->number, i, info->offset);
             info->state = ASTE_RUNNING;
         }
         else
@@ -424,7 +445,7 @@
 //
 //==========================================================================
 
-static void StartOpenACS(int number, int infoIndex, int *address)
+static void StartOpenACS(int number, int infoIndex, int offset)
 {
     acs_t *script;
 
@@ -436,7 +457,7 @@
     script->delayCount = 35;
 
     script->infoIndex = infoIndex;
-    script->ip = address;
+    script->ip = offset;
     script->thinker.function = T_InterpretACS;
     P_AddThinker(&script->thinker);
 }
@@ -517,7 +538,7 @@
     script->activator = activator;
     script->line = line;
     script->side = side;
-    script->ip = ACSInfo[infoIndex].address;
+    script->ip = ACSInfo[infoIndex].offset;
     script->thinker.function = T_InterpretACS;
     for (i = 0; i < MAX_SCRIPT_ARGS && i < ACSInfo[infoIndex].argCount; i++)
     {
@@ -697,17 +718,15 @@
         return;
     }
     ACScript = script;
-    PCodePtr = ACScript->ip;
+    PCodeOffset = ACScript->ip;
 
     do
     {
-        cmd = LONG(*PCodePtr);
-        ++PCodePtr;
-
-        action = PCodeCmds[cmd] ();
+        cmd = ReadCodeInt();
+        action = PCodeCmds[cmd]();
     } while (action == SCRIPT_CONTINUE);
 
-    ACScript->ip = PCodePtr;
+    ACScript->ip = PCodeOffset;
 
     if (action == SCRIPT_TERMINATE)
     {
@@ -898,25 +917,6 @@
 
 //==========================================================================
 //
-// ReadCodeImmediate
-//
-// Some instructions take "immediate" parameters which are stored in the
-// bytecode immediately following the instruction. This function should be
-// used to read them.
-//
-//==========================================================================
-
-static int ReadCodeImmediate(void)
-{
-    int result;
-    // TODO: Add bounds checking
-    result = LONG(*PCodePtr);
-    ++PCodePtr;
-    return result;
-}
-
-//==========================================================================
-//
 // ReadScriptVar
 //
 // Read a script variable index as an immediate value, validating the
@@ -926,7 +926,7 @@
 
 static int ReadScriptVar(void)
 {
-    int var = ReadCodeImmediate();
+    int var = ReadCodeInt();
     ACSAssert(var >= 0, "negative script variable: %d < 0", var);
     ACSAssert(var < MAX_ACS_SCRIPT_VARS,
               "invalid script variable: %d >= %d", var, MAX_ACS_SCRIPT_VARS);
@@ -944,7 +944,7 @@
 
 static int ReadMapVar(void)
 {
-    int var = ReadCodeImmediate();
+    int var = ReadCodeInt();
     ACSAssert(var >= 0, "negative map variable: %d < 0", var);
     ACSAssert(var < MAX_ACS_MAP_VARS,
               "invalid map variable: %d >= %d", var, MAX_ACS_MAP_VARS);
@@ -962,7 +962,7 @@
 
 static int ReadWorldVar(void)
 {
-    int var = ReadCodeImmediate();
+    int var = ReadCodeInt();
     ACSAssert(var >= 0, "negative world variable: %d < 0", var);
     ACSAssert(var < MAX_ACS_WORLD_VARS,
               "invalid world variable: %d >= %d", var, MAX_ACS_WORLD_VARS);
@@ -1011,7 +1011,7 @@
 
 static int CmdPushNumber(void)
 {
-    Push(ReadCodeImmediate());
+    Push(ReadCodeInt());
     return SCRIPT_CONTINUE;
 }
 
@@ -1019,7 +1019,7 @@
 {
     int special;
 
-    special = ReadCodeImmediate();
+    special = ReadCodeInt();
     SpecArgs[0] = Pop();
     P_ExecuteLineSpecial(special, SpecArgs, ACScript->line,
                          ACScript->side, ACScript->activator);
@@ -1030,7 +1030,7 @@
 {
     int special;
 
-    special = ReadCodeImmediate();
+    special = ReadCodeInt();
     SpecArgs[1] = Pop();
     SpecArgs[0] = Pop();
     P_ExecuteLineSpecial(special, SpecArgs, ACScript->line,
@@ -1042,7 +1042,7 @@
 {
     int special;
 
-    special = ReadCodeImmediate();
+    special = ReadCodeInt();
     SpecArgs[2] = Pop();
     SpecArgs[1] = Pop();
     SpecArgs[0] = Pop();
@@ -1055,7 +1055,7 @@
 {
     int special;
 
-    special = ReadCodeImmediate();
+    special = ReadCodeInt();
     SpecArgs[3] = Pop();
     SpecArgs[2] = Pop();
     SpecArgs[1] = Pop();
@@ -1069,7 +1069,7 @@
 {
     int special;
 
-    special = ReadCodeImmediate();
+    special = ReadCodeInt();
     SpecArgs[4] = Pop();
     SpecArgs[3] = Pop();
     SpecArgs[2] = Pop();
@@ -1084,8 +1084,8 @@
 {
     int special;
 
-    special = ReadCodeImmediate();
-    SpecArgs[0] = ReadCodeImmediate();
+    special = ReadCodeInt();
+    SpecArgs[0] = ReadCodeInt();
     P_ExecuteLineSpecial(special, SpecArgs, ACScript->line,
                          ACScript->side, ACScript->activator);
     return SCRIPT_CONTINUE;
@@ -1095,9 +1095,9 @@
 {
     int special;
 
-    special = ReadCodeImmediate();
-    SpecArgs[0] = ReadCodeImmediate();
-    SpecArgs[1] = ReadCodeImmediate();
+    special = ReadCodeInt();
+    SpecArgs[0] = ReadCodeInt();
+    SpecArgs[1] = ReadCodeInt();
     P_ExecuteLineSpecial(special, SpecArgs, ACScript->line,
                          ACScript->side, ACScript->activator);
     return SCRIPT_CONTINUE;
@@ -1107,10 +1107,10 @@
 {
     int special;
 
-    special = ReadCodeImmediate();
-    SpecArgs[0] = ReadCodeImmediate();
-    SpecArgs[1] = ReadCodeImmediate();
-    SpecArgs[2] = ReadCodeImmediate();
+    special = ReadCodeInt();
+    SpecArgs[0] = ReadCodeInt();
+    SpecArgs[1] = ReadCodeInt();
+    SpecArgs[2] = ReadCodeInt();
     P_ExecuteLineSpecial(special, SpecArgs, ACScript->line,
                          ACScript->side, ACScript->activator);
     return SCRIPT_CONTINUE;
@@ -1120,11 +1120,11 @@
 {
     int special;
 
-    special = ReadCodeImmediate();
-    SpecArgs[0] = ReadCodeImmediate();
-    SpecArgs[1] = ReadCodeImmediate();
-    SpecArgs[2] = ReadCodeImmediate();
-    SpecArgs[3] = ReadCodeImmediate();
+    special = ReadCodeInt();
+    SpecArgs[0] = ReadCodeInt();
+    SpecArgs[1] = ReadCodeInt();
+    SpecArgs[2] = ReadCodeInt();
+    SpecArgs[3] = ReadCodeInt();
     P_ExecuteLineSpecial(special, SpecArgs, ACScript->line,
                          ACScript->side, ACScript->activator);
     return SCRIPT_CONTINUE;
@@ -1134,12 +1134,12 @@
 {
     int special;
 
-    special = ReadCodeImmediate();
-    SpecArgs[0] = ReadCodeImmediate();
-    SpecArgs[1] = ReadCodeImmediate();
-    SpecArgs[2] = ReadCodeImmediate();
-    SpecArgs[3] = ReadCodeImmediate();
-    SpecArgs[4] = ReadCodeImmediate();
+    special = ReadCodeInt();
+    SpecArgs[0] = ReadCodeInt();
+    SpecArgs[1] = ReadCodeInt();
+    SpecArgs[2] = ReadCodeInt();
+    SpecArgs[3] = ReadCodeInt();
+    SpecArgs[4] = ReadCodeInt();
     P_ExecuteLineSpecial(special, SpecArgs, ACScript->line,
                          ACScript->side, ACScript->activator);
     return SCRIPT_CONTINUE;
@@ -1396,10 +1396,7 @@
 
 static int CmdGoto(void)
 {
-    int offset;
-
-    offset = ValidateLumpOffset(ReadCodeImmediate(), "CmdGoto parameter");
-    PCodePtr = (int *) (ActionCodeBase + offset);
+    PCodeOffset = ValidateLumpOffset(ReadCodeInt(), "CmdGoto parameter");
     return SCRIPT_CONTINUE;
 }
 
@@ -1407,11 +1404,11 @@
 {
     int offset;
 
-    offset = ValidateLumpOffset(ReadCodeImmediate(), "CmdIfGoto parameter");
+    offset = ValidateLumpOffset(ReadCodeInt(), "CmdIfGoto parameter");
 
     if (Pop() != 0)
     {
-        PCodePtr = (int *) (ActionCodeBase + offset);
+        PCodeOffset = offset;
     }
     return SCRIPT_CONTINUE;
 }
@@ -1430,7 +1427,7 @@
 
 static int CmdDelayDirect(void)
 {
-    ACScript->delayCount = ReadCodeImmediate();
+    ACScript->delayCount = ReadCodeInt();
     return SCRIPT_STOP;
 }
 
@@ -1450,8 +1447,8 @@
     int low;
     int high;
 
-    low = ReadCodeImmediate();
-    high = ReadCodeImmediate();
+    low = ReadCodeInt();
+    high = ReadCodeInt();
     Push(low + (P_Random() % (high - low + 1)));
     return SCRIPT_CONTINUE;
 }
@@ -1469,8 +1466,8 @@
 {
     int type;
 
-    type = ReadCodeImmediate();
-    ThingCount(type, ReadCodeImmediate());
+    type = ReadCodeInt();
+    ThingCount(type, ReadCodeInt());
     return SCRIPT_CONTINUE;
 }
 
@@ -1540,7 +1537,7 @@
 
 static int CmdTagWaitDirect(void)
 {
-    ACSInfo[ACScript->infoIndex].waitValue = ReadCodeImmediate();
+    ACSInfo[ACScript->infoIndex].waitValue = ReadCodeInt();
     ACSInfo[ACScript->infoIndex].state = ASTE_WAITINGFORTAG;
     return SCRIPT_STOP;
 }
@@ -1554,7 +1551,7 @@
 
 static int CmdPolyWaitDirect(void)
 {
-    ACSInfo[ACScript->infoIndex].waitValue = ReadCodeImmediate();
+    ACSInfo[ACScript->infoIndex].waitValue = ReadCodeInt();
     ACSInfo[ACScript->infoIndex].state = ASTE_WAITINGFORPOLY;
     return SCRIPT_STOP;
 }
@@ -1581,8 +1578,8 @@
     int flat;
     int sectorIndex;
 
-    tag = ReadCodeImmediate();
-    flat = R_FlatNumForName(StringLookup(ReadCodeImmediate()));
+    tag = ReadCodeInt();
+    flat = R_FlatNumForName(StringLookup(ReadCodeInt()));
     sectorIndex = -1;
     while ((sectorIndex = P_FindSectorFromTag(tag, sectorIndex)) >= 0)
     {
@@ -1613,8 +1610,8 @@
     int flat;
     int sectorIndex;
 
-    tag = ReadCodeImmediate();
-    flat = R_FlatNumForName(StringLookup(ReadCodeImmediate()));
+    tag = ReadCodeInt();
+    flat = R_FlatNumForName(StringLookup(ReadCodeInt()));
     sectorIndex = -1;
     while ((sectorIndex = P_FindSectorFromTag(tag, sectorIndex)) >= 0)
     {
@@ -1625,7 +1622,7 @@
 
 static int CmdRestart(void)
 {
-    PCodePtr = ACSInfo[ACScript->infoIndex].address;
+    PCodeOffset = ACSInfo[ACScript->infoIndex].offset;
     return SCRIPT_CONTINUE;
 }
 
@@ -1693,11 +1690,11 @@
 {
     int offset;
 
-    offset = ValidateLumpOffset(ReadCodeImmediate(), "CmdIfNotGoto parameter");
+    offset = ValidateLumpOffset(ReadCodeInt(), "CmdIfNotGoto parameter");
 
     if (Pop() == 0)
     {
-        PCodePtr = (int *) (ActionCodeBase + offset);
+        PCodeOffset = offset;
     }
     return SCRIPT_CONTINUE;
 }
@@ -1717,7 +1714,7 @@
 
 static int CmdScriptWaitDirect(void)
 {
-    ACSInfo[ACScript->infoIndex].waitValue = ReadCodeImmediate();
+    ACSInfo[ACScript->infoIndex].waitValue = ReadCodeInt();
     ACSInfo[ACScript->infoIndex].state = ASTE_WAITINGFORSCRIPT;
     return SCRIPT_STOP;
 }
@@ -1736,12 +1733,12 @@
     int value;
     int offset;
 
-    value = ReadCodeImmediate();
-    offset = ValidateLumpOffset(ReadCodeImmediate(), "CmdCaseGoto parameter");
+    value = ReadCodeInt();
+    offset = ValidateLumpOffset(ReadCodeInt(), "CmdCaseGoto parameter");
 
     if (Top() == value)
     {
-        PCodePtr = (int *) (ActionCodeBase + offset);
+        PCodeOffset = offset;
         Drop();
     }
 
--- a/src/hexen/p_spec.h
+++ b/src/hexen/p_spec.h
@@ -507,7 +507,7 @@
 struct acsInfo_s
 {
     int number;
-    int *address;
+    int offset;
     int argCount;
     aste_t state;
     int waitValue;
@@ -525,7 +525,7 @@
     int stack[ACS_STACK_DEPTH];
     int stackPtr;
     int vars[MAX_ACS_SCRIPT_VARS];
-    int *ip;
+    int ip;
 };
 
 typedef struct
--- a/src/hexen/sv_save.c
+++ b/src/hexen/sv_save.c
@@ -1593,8 +1593,7 @@
     }
 
     // int *ip;
-    i = SV_ReadLong();
-    str->ip = (int *) (ActionCodeBase + i);
+    str->ip = SV_ReadLong();
 }
 
 static void StreamOut_acs_t(acs_t *str)
@@ -1645,7 +1644,7 @@
     }
 
     // int *ip;
-    SV_WriteLong((byte *) str->ip - ActionCodeBase);
+    SV_WriteLong(str->ip);
 }