(svn r19643) -Fix (r19120): Industry generation failed for large maps and lots of industry types.

src/core/random_func.cpp

@@ -57,6 +57,7 @@ uint32 DoRandom(int line, const char *file)
 
 uint DoRandomRange(uint max, int line, const char *file)
 {
+	assert(max <= UINT16_MAX);
 	return GB(DoRandom(line, file), 0, 16) * max >> 16;
 }
 #endif /* RANDOM_DEBUG */

src/core/random_func.hpp

@@ -99,8 +99,9 @@ void SetRandomSeed(uint32 seed);
 		return _random.Next();
 	}
 
-	static FORCEINLINE uint32 RandomRange(uint16 max)
+	static FORCEINLINE uint32 RandomRange(uint max)
 	{
+		assert(max <= UINT16_MAX);
 		return _random.Next(max);
 	}
 #endif

src/industry_cmd.cpp

@@ -1923,7 +1923,8 @@ void GenerateIndustries()
 
 	/* Add the remaining industries according to their probabilities */
 	for (uint i = 0; i < total_amount; i++) {
-		uint32 r = RandomRange(total_prob);
+		/* RandomRange() can only deal with 16 bit, which is not enough here. */
+		uint32 r = ((uint64)Random() * (uint64)total_prob) >> 32;
 		IndustryType it = 0;
 		while (it < NUM_INDUSTRYTYPES && r >= industry_probs[it]) {
 			r -= industry_probs[it];