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Update examples in waveballot.md and waveactivecountbits.md #2077

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Update examples in waveballot.md and waveactivecountbits.md #2077

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Update waveactivecountbits.md
damyanp Jul 11, 2025
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Fixup examples
damyanp Jul 11, 2025
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damyanp Jul 11, 2025
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2 changes: 1 addition & 1 deletion desktop-src/direct3dhlsl/waveactivecountbits.md
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Expand Up @@ -58,7 +58,7 @@ This function is supported from shader model 6.0 in all shader stages.
This can be implemented more efficiently than a full WaveActiveSum, as described in the following example:
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@tex3d tex3d Jul 11, 2025

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Maybe this line should be clarified that this is meant to demonstrate what this operation does:

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This can be implemented more efficiently than a full WaveActiveSum, as described in the following example:
This can be implemented more efficiently than a full WaveActiveSum, in a way similar to this equivalent code:

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@damyanp damyanp Jul 11, 2025

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Tried another way to put this, hopefully this is clearer?


``` syntax
result = WaveActiveCountBits( WaveActiveBallot( bBit ) );
result = countbits( WaveActiveBallot( bBit ) );
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@tex3d tex3d Jul 11, 2025 •
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This is an improvement, but still not quite correct HLSL. It needs to be more like this:

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result = countbits( WaveActiveBallot( bBit ) );
uint4 counts = countbits( WaveActiveBallot( bBit ) );
result = counts.x + counts.y + counts.z + counts.w;

This is because WaveActiveBallow returns a uint4 in order to have one bit for every potential lane in the widest possible lane width of 128.

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@damyanp damyanp Jul 11, 2025

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Thanks! Updated.

```

## See also
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