| int Impala::Util::Random::GetInt | ( | int | upperBound | ) | [inline] |
Gives a random integer in range [0,i).
Definition at line 76 of file Random.h.
References GetRandMax(), ILOG_ERROR, ILOG_WARNING, and Next().
00077 { 00078 if(upperBound < 0) 00079 { 00080 ILOG_ERROR("upperbound must be positive"); 00081 return 0; 00082 } 00083 if(upperBound > GetRandMax()) 00084 ILOG_WARNING(upperBound <<" upperBound > rand max "<< GetRandMax()); 00085 00086 // special case for when upperBound is a power of two: return the 00087 // higher-order bits in stead of the lower order. These have better 00088 // statistical properties. 00089 if(!((upperBound -1) & upperBound)) // (x-1)&x is 0 iff x is a power of two 00090 return (int)((upperBound * (UInt64)Next(31)) >> 31); 00091 00092 // Because of the modulo some values would be returned more than 00093 // others. This loop rejects these numbers 00094 int bits, val; 00095 do { 00096 bits = Next(31); 00097 val = bits % upperBound; 00098 } while(bits - val + (upperBound-1) < 0); // this check works because of 00099 // overflow 00100 return val; 00101 }
Here is the call graph for this function:
