File size: 3,467 Bytes
5d5e27b f85db5e 5d5e27b f85db5e 5d5e27b f85db5e 66e0e23 f85db5e 66e0e23 f85db5e 66e0e23 f85db5e 66e0e23 f85db5e 66e0e23 f85db5e 66e0e23 f85db5e | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 | ---
library_name: kernels
license: apache-2.0
tags:
- kernel
- webgpu
- wgsl
---
# ai.onnx.Scan
`ai.onnx` · internal tensor lowering (non-standard) · reviewed against ONNX opset 25
## Description
Internal additive prefix-scan lowering over one rank-1 state and one rank-2 input, with forward and reverse traversal. This package does not implement ONNX `Scan` body-graph semantics.
See the [standard ONNX `Scan` spec](https://onnx.ai/onnx/operators/onnx__Scan.html) for the contract this internal lowering does not implement.
## Inputs
| Name | Logical dtype | Rank | Shape | Description | Presence |
| --- | --- | --- | --- | --- | --- |
| `initial_state` | `T` | `1` | — | Initial rank-1 additive state of shape `[dim]`. | required |
| `scan_input` | `T` | `2` | — | Rank-2 input of shape `[steps, dim]`. Each row is added to the running state in forward or reverse traversal order. | required |
## Outputs
| Name | Logical dtype | Rank | Shape | Description | Presence |
| --- | --- | --- | --- | --- | --- |
| `final_state` | `T` | `1` | same as `initial_state` | Final rank-1 state of shape `[dim]` after all input rows have been accumulated. | required |
| `scan_output` | `T` | `2` | same as `scan_input` | Inclusive additive prefix results with the same `[steps, dim]` shape as `scan_input`. Reverse traversal still writes each result at its corresponding input row. | required |
## Attributes
Default values (overridable per request):
| Attribute | Default | Description |
| --- | --- | --- |
| `reverse` | `0` | When non-zero, the scan input sequence is traversed in reverse order (equivalent to `scan_input_directions=1`); default `0` scans forward. |
## Type constraints
| Variable | Allowed dtypes |
| --- | --- |
| `T` | `float32` |
## Files
- [`metadata.json`](build/webgpu/metadata.json) — kernel metadata (id, digests, per-variant templates, provenance)
- [`manifest.json`](build/webgpu/manifest.json) — the op contract (source of truth)
- [`test.json`](build/webgpu/test.json) — correctness cases
- [`bench.json`](build/webgpu/bench.json) — benchmark + tuning cases
- [`scan-coop-channel.wgsl.jinja`](build/webgpu/scan-coop-channel.wgsl.jinja)
- [`scan-multichunk-apply.wgsl.jinja`](build/webgpu/scan-multichunk-apply.wgsl.jinja)
- [`scan-multichunk-carries.wgsl.jinja`](build/webgpu/scan-multichunk-carries.wgsl.jinja)
- [`scan-multichunk-local.wgsl.jinja`](build/webgpu/scan-multichunk-local.wgsl.jinja)
- [`scan-prefix-sum.wgsl.jinja`](build/webgpu/scan-prefix-sum.wgsl.jinja)
## Use with `@huggingface/kernels`
```sh
npm install --save-exact @huggingface/kernels@0.0.1-preview.2
```
Required output shapes and logical data types are inferred from the supplied inputs and attributes; result tensors are allocated automatically.
The `version: 1` option selects the published kernel contract; it is independent of any operator opset, contrib `since_version`, or model version.
It follows the `v1` branch as fixes land. To pin exact artifact bytes, pass a 40-character commit `revision` instead of `version`.
Replace each `*Data` placeholder with a typed array containing the corresponding input data.
```js
import { getKernel } from "@huggingface/kernels";
const kernel = await getKernel("webgpu-kernels/ai.onnx.Scan", { version: 1 });
const { final_state, scan_output } = await kernel({
initial_state: { data: initial_stateData, shape: [1] },
scan_input: { data: scan_inputData, shape: [3, 1] },
});
```
|