RNG: do not rely on implicit conversions in arithmetic expressions

Source/engine.cpp

@@ -16,20 +16,20 @@
 DEVILUTION_BEGIN_NAMESPACE
 
 /** Seed value before the most recent call to SetRndSeed() */
-int orgseed;
+Sint32 orgseed;
 /** Current game seed */
-int sglGameSeed;
+Sint32 sglGameSeed;
 static CCritSect sgMemCrit;
 
 /**
  * Specifies the increment used in the Borland C/C++ pseudo-random.
  */
-const int RndInc = 1;
+const Uint32 RndInc = 1;
 
 /**
  * Specifies the multiplier used in the Borland C/C++ pseudo-random number generator algorithm.
  */
-const int RndMult = 0x015A4E35;
+const Uint32 RndMult = 0x015A4E35;
 
 void CelDrawTo(CelOutputBuffer out, int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth)
 {
@@ -634,7 +634,7 @@ int GetDirection(int x1, int y1, int x2, int y2)
  * @brief Set the RNG seed
  * @param s RNG seed
  */
-void SetRndSeed(int s)
+void SetRndSeed(Sint32 s)
 {
 	sglGameSeed = s;
 	orgseed = s;
@@ -644,9 +644,9 @@ void SetRndSeed(int s)
  * @brief Advance the internal RNG seed and return the new value
  * @return RNG seed
  */
-int AdvanceRndSeed()
+Sint32 AdvanceRndSeed()
 {
-	sglGameSeed = static_cast<unsigned int>(RndMult) * sglGameSeed + RndInc;
+	sglGameSeed = (RndMult * static_cast<Uint32>(sglGameSeed)) + RndInc;
 	return abs(sglGameSeed);
 }
 
@@ -654,7 +654,7 @@ int AdvanceRndSeed()
  * @brief Get the current RNG seed
  * @return RNG seed
  */
-int GetRndSeed()
+Sint32 GetRndSeed()
 {
 	return abs(sglGameSeed);
 }
@@ -665,7 +665,7 @@ int GetRndSeed()
  * @param v The upper limit for the return value
  * @return A random number from 0 to (v-1)
  */
-int random_(BYTE idx, int v)
+Sint32 random_(BYTE idx, Sint32 v)
 {
 	if (v <= 0)
 		return 0;

Source/engine.h

@@ -323,9 +323,9 @@ void DrawHalfTransparentRectTo(CelOutputBuffer out, int sx, int sy, int width, i
 int GetDirection(int x1, int y1, int x2, int y2);
 
 void SetRndSeed(int s);
-int AdvanceRndSeed();
-int GetRndSeed();
-int random_(BYTE idx, int v);
+Sint32 AdvanceRndSeed();
+Sint32 GetRndSeed();
+Sint32 random_(BYTE idx, int v);
 BYTE *DiabloAllocPtr(DWORD dwBytes);
 void mem_free_dbg(void *p);
 BYTE *LoadFileInMem(const char *pszName, DWORD *pdwFileLen);