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Tiny optimizations. #1

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a09f50d
Do float math with floats, avoid needless casting and double math.
bmprovan Jan 21, 2017
d1ee4f2
Dodge a few unnecessary operations in NextBool.
bmprovan Jan 21, 2017
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11 changes: 6 additions & 5 deletions PCGSharp/Source/Pcg.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,9 @@ public class Pcg {
const ulong ShiftedIncrement = 721347520444481703ul;
ulong _increment = 1442695040888963407ul;
const ulong Multiplier = 6364136223846793005ul;
const float ToFloat01 = 1.0f / 4294967296.0f;
const double ToDouble01 = 1.0 / 4294967296.0;
const uint HalfUint = uint.MaxValue / 2;

// This attribute ensures that every thread will get its own instance of PCG.
// An alternative, since PCG supports streams, is to use a different stream per
Expand Down Expand Up @@ -215,21 +217,21 @@ public uint[] NextUInts(int count, uint minInclusive, uint maxExclusive) {
}

public float NextFloat() {
return (float)(NextUInt() * ToDouble01);
return NextUInt() * ToFloat01;
}

public float NextFloat(float maxInclusive) {
if(maxInclusive <= 0)
throw new ArgumentException("MaxInclusive must be larger than 0");

return (float)(NextUInt() * ToDouble01) * maxInclusive;
return NextUInt() * ToFloat01 * maxInclusive;
}

public float NextFloat(float minInclusive, float maxInclusive) {
if(maxInclusive < minInclusive)
throw new ArgumentException("Max must be larger than min");

return (float)(NextUInt() * ToDouble01) * (maxInclusive-minInclusive) + minInclusive;
return NextUInt() * ToFloat01 * (maxInclusive-minInclusive) + minInclusive;
}

public float[] NextFloats(int count) {
Expand Down Expand Up @@ -333,8 +335,7 @@ public byte[] NextBytes(int count) {
}

public bool NextBool() {
var result = NextUInt();
return result % 2 == 1;
return NextUInt() < HalfUint;
}

public bool[] NextBools(int count) {
Expand Down
11 changes: 6 additions & 5 deletions PCGSharp/Source/PcgExtended.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -94,7 +94,9 @@ public class PcgExtended {
const uint McgUnmultiplier = 2897767785u;

// 1 / (uint.MaxValue + 1)
const float ToFloat01 = 1.0f / 4294967296.0f;
const double ToDouble01 = 1.0 / 4294967296.0;
const uint HalfUint = uint.MaxValue / 2;
uint[] _data;

// This attribute ensures that every thread will get its own instance of PCG.
Expand Down Expand Up @@ -265,21 +267,21 @@ public uint[] NextUInts(int count, uint minInclusive, uint maxExclusive) {
}

public float NextFloat() {
return (float)(NextUInt() * ToDouble01);
return (NextUInt() * ToFloat01);
}

public float NextFloat(float maxInclusive) {
if(maxInclusive <= 0)
throw new ArgumentException("Max must be larger than 0");

return (float)(NextUInt() * ToDouble01) * maxInclusive;
return (NextUInt() * ToFloat01) * maxInclusive;
}

public float NextFloat(float minInclusive, float maxInclusive) {
if(maxInclusive < minInclusive)
throw new ArgumentException("Max must be larger than min");

return (float)(NextUInt() * ToDouble01) * (maxInclusive-minInclusive) + minInclusive;
return (NextUInt() * ToFloat01) * (maxInclusive-minInclusive) + minInclusive;
}

public float[] NextFloats(int count) {
Expand Down Expand Up @@ -383,8 +385,7 @@ public byte[] NextBytes(int count) {
}

public bool NextBool() {
uint result = NextUInt();
return ((result % 2) == 1);
return NextUInt() < HalfUint;
}

public bool[] NextBools(int count) {
Expand Down