Much like an early civilization with no concept of the number zero, the

new memory manager didn't have the concept of the NULL pointer. Now it
does.

If ScummVM ever crashed for you when using the phone early in the game,
this patch hopefully fixes that bug. (If it didn't crash for you, memory
block zero was still allocated, so 0 still decoded to a valid pointer.)

svn-id: r14937

1 files changed, 11 insertions, 3 deletions

diff --git a/sword2/memory.cpp b/sword2/memory.cpp
index c8f0087996..6d348cfd29 100644
--- a/sword2/memory.cpp
+++ b/sword2/memory.cpp
@@ -37,6 +37,8 @@
 // could only handle up to 999 blocks of memory. That means we can encode a
 // pointer as a 10-bit id and a 22-bit offset into the block. Judging by early
 // testing, both should be plenty.
+//
+// The number zero is used to represent the NULL pointer.
 
 #include "common/stdafx.h"
 #include "sword2/sword2.h"
@@ -92,6 +94,9 @@ MemoryManager::~MemoryManager() {
 }
 
 int32 MemoryManager::encodePtr(byte *ptr) {
+	if (ptr == NULL)
+		return 0;
+
 	int idx = findPointerInIndex(ptr);
 
 	assert(idx != -1);
@@ -99,15 +104,18 @@ int32 MemoryManager::encodePtr(byte *ptr) {
 	uint32 id = _memBlockIndex[idx]->id;
 	uint32 offset = ptr - _memBlocks[id].ptr;
 
-	assert(id <= 0x03ff);
+	assert(id < 0x03ff);
 	assert(offset <= 0x003fffff);
 	assert(offset < _memBlocks[id].size);
 
-	return (id << 22) | (ptr - _memBlocks[id].ptr);
+	return ((id + 1) << 22) | (ptr - _memBlocks[id].ptr);
 }
 
 byte *MemoryManager::decodePtr(int32 n) {
-	uint32 id = (n & 0xffc00000) >> 22;
+	if (n == 0)
+		return NULL;
+
+	uint32 id = ((n & 0xffc00000) >> 22) - 1;
 	uint32 offset = n & 0x003fffff;
 
 	assert(_memBlocks[id].ptr);