Created
October 29, 2016 13:18
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An HLSL for computing prefix sum of 64 values using LDS
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| uint ReadSlotId(uint LaneId, uint mask0, uint mask1) | |
| { | |
| return LaneId & (0x20 | mask0) | mask1; | |
| } | |
| void LdsBarrier() {} | |
| groupshared float Scratch[64]; | |
| float PrefixSum64(uint LaneId, float x) | |
| { | |
| Scratch[LaneId] = x; LdsBarrier(); | |
| if (LaneId & 0x01) Scratch[LaneId] += Scratch[ReadSlotId(LaneId, 0x1e, 0x0)]; LdsBarrier(); | |
| if (LaneId & 0x02) Scratch[LaneId] += Scratch[ReadSlotId(LaneId, 0x1c, 0x1)]; LdsBarrier(); | |
| if (LaneId & 0x04) Scratch[LaneId] += Scratch[ReadSlotId(LaneId, 0x18, 0x3)]; LdsBarrier(); | |
| if (LaneId & 0x08) Scratch[LaneId] += Scratch[ReadSlotId(LaneId, 0x10, 0x7)]; LdsBarrier(); | |
| if (LaneId & 0x10) Scratch[LaneId] += Scratch[ReadSlotId(LaneId, 0x00, 0xf)]; LdsBarrier(); | |
| if (LaneId & 0x20) Scratch[LaneId] += Scratch[31]; LdsBarrier(); | |
| return Scratch[LaneId]; | |
| } |
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