# heliaCORE.Reshape

## arm_resize_nearest_neighbor_f32_get_buffer_size

`function` · `c`

```c
int32_t arm_resize_nearest_neighbor_f32_get_buffer_size(const cmsis_nn_dims *output_dims)
```

Scratch size in bytes for `arm_resize_nearest_neighbor_f32()` / `arm_resize_nearest_neighbor_f16()`.

The kernels precompute one int32_t input index per output row and per output column, so the requirement is (output_dims->h + output_dims->w) * sizeof(int32_t). Returns -1 (never 0) when `output_dims` is NULL, when h or w is less than 1, or when the size does not fit in int32_t; a negative result must not be used to size a buffer, and the kernels reject a { NULL, 0 } context outright (the -1 family of the integer sizers, not the 0-returning family most float sizers use; see the sentinel note on arm_nn_size_mul).

**Parameters**

| Name | Type | Direction | Description |
| --- | --- | --- | --- |
| output_dims | const cmsis_nn_dims * | in | Output tensor dimensions (only h and w are read). |

**Returns**

| Name | Type | Description |
| --- | --- | --- |
|  |  | Required ctx->size in bytes, or -1. |

Source: `Include/arm_nnfunctions_flt.h:1425`

## arm_resize_nearest_neighbor_f32

`function` · `c`

```c
arm_cmsis_nn_status arm_resize_nearest_neighbor_f32(
    const cmsis_nn_context *ctx,
    const cmsis_nn_resize_params *resize_params,
    const cmsis_nn_dims *input_shape,
    const float32_t *input_data,
    const cmsis_nn_dims *output_size_shape,
    const int32_t *output_size_data,
    const cmsis_nn_dims *output_shape,
    float32_t *output_data
)
```

Nearest-neighbor resize of a float32 NHWC tensor.

Pure data movement: every output element is a bit copy of one input element, so NaN (sign and payload), +/-Inf, -0.0 and subnormals are preserved bit-for-bit on the scalar and MVE legs alike (the MVE copy is a tail-predicated vldr/vstr pair, not an FP operation, so FPSCR flush-to-zero and default-NaN do not apply). No arithmetic is performed on the data; the only float math is the float32 index scale below.

Index semantics are TFLite's RESIZE_NEAREST_NEIGHBOR reference, evaluated in float32 per axis: scale = (align_corners && out > 1) ? (in - 1) / (out - 1) : in / out idx = align_corners ? roundf((o + offset) * scale) : floorf((o + offset) * scale) idx = min(idx, in - 1); if (half_pixel_centers) idx = max(idx, 0) with offset = half_pixel_centers ? 0.5f : 0.0f; roundf rounds ties away from zero, matching TfLiteRound. All four align_corners/half_pixel_centers combinations were verified bit-for-bit against TFLite 2.20 over a shape sweep (1..16 square, 80 random NHWC shapes up to 40x40, 224->7 and 7->224), including the out == 1 align_corners case, which maps to input index 0.

**Parameters**

| Name | Type | Direction | Description |
| --- | --- | --- | --- |
| ctx | const cmsis_nn_context * | in | Scratch context. ctx->buf must be non-NULL and 4-byte aligned, and ctx->size at least arm_resize_nearest_neighbor_f32_get_buffer_size(output_shape); the kernel writes the x/y index maps here and does not read them after returning. |
| resize_params | const cmsis_nn_resize_params * | in | align_corners / half_pixel_centers. |
| input_shape | const cmsis_nn_dims * | in | Input tensor dimensions in NHWC format; every dimension must be >= 1. |
| input_data | const float32_t * | in | Input tensor data. Must not overlap `output_data`. |
| output_size_shape | const cmsis_nn_dims * | in | Dimensions of the output-size tensor; must hold exactly 2 elements. |
| output_size_data | const int32_t * | in | Output size as [output_height, output_width], both >= 1. |
| output_shape | const cmsis_nn_dims * | in | Output tensor dimensions in NHWC format; n and c must equal the input's and h/w must equal `output_size_data`. |
| output_data | float32_t * | out | Output tensor data. |

**Returns**

| Name | Type | Description |
| --- | --- | --- |
|  |  | ARM_CMSIS_NN_SUCCESS, or ARM_CMSIS_NN_ARG_ERROR when any constraint above fails (including a NULL pointer argument); nothing is written on ARG_ERROR. |

Source: `Include/arm_nnfunctions_flt.h:1458`

## arm_resize_nearest_neighbor_f16_get_buffer_size

`function` · `c`

```c
int32_t arm_resize_nearest_neighbor_f16_get_buffer_size(const cmsis_nn_dims *output_dims)
```

Scratch size in bytes for `arm_resize_nearest_neighbor_f32()` / `arm_resize_nearest_neighbor_f16()`.

The kernels precompute one int32_t input index per output row and per output column, so the requirement is (output_dims->h + output_dims->w) * sizeof(int32_t). Returns -1 (never 0) when `output_dims` is NULL, when h or w is less than 1, or when the size does not fit in int32_t; a negative result must not be used to size a buffer, and the kernels reject a { NULL, 0 } context outright (the -1 family of the integer sizers, not the 0-returning family most float sizers use; see the sentinel note on arm_nn_size_mul).

**Parameters**

| Name | Type | Direction | Description |
| --- | --- | --- | --- |
| output_dims | const cmsis_nn_dims * | in | Output tensor dimensions (only h and w are read). |

**Returns**

| Name | Type | Description |
| --- | --- | --- |
|  |  | Required ctx->size in bytes, or -1. |

Source: `Include/arm_nnfunctions_flt.h:3294`

## arm_resize_nearest_neighbor_f16

`function` · `c`

```c
arm_cmsis_nn_status arm_resize_nearest_neighbor_f16(
    const cmsis_nn_context *ctx,
    const cmsis_nn_resize_params *resize_params,
    const cmsis_nn_dims *input_shape,
    const float16_t *input_data,
    const cmsis_nn_dims *output_size_shape,
    const int32_t *output_size_data,
    const cmsis_nn_dims *output_shape,
    float16_t *output_data
)
```

Nearest-neighbor resize of a float32 NHWC tensor.

Pure data movement: every output element is a bit copy of one input element, so NaN (sign and payload), +/-Inf, -0.0 and subnormals are preserved bit-for-bit on the scalar and MVE legs alike (the MVE copy is a tail-predicated vldr/vstr pair, not an FP operation, so FPSCR flush-to-zero and default-NaN do not apply). No arithmetic is performed on the data; the only float math is the float32 index scale below.

Index semantics are TFLite's RESIZE_NEAREST_NEIGHBOR reference, evaluated in float32 per axis: scale = (align_corners && out > 1) ? (in - 1) / (out - 1) : in / out idx = align_corners ? roundf((o + offset) * scale) : floorf((o + offset) * scale) idx = min(idx, in - 1); if (half_pixel_centers) idx = max(idx, 0) with offset = half_pixel_centers ? 0.5f : 0.0f; roundf rounds ties away from zero, matching TfLiteRound. All four align_corners/half_pixel_centers combinations were verified bit-for-bit against TFLite 2.20 over a shape sweep (1..16 square, 80 random NHWC shapes up to 40x40, 224->7 and 7->224), including the out == 1 align_corners case, which maps to input index 0.

:::note
float16 twin: each element is copied as a 16-bit lane with no widening or conversion, so half-precision NaN payloads and subnormals are preserved exactly and the data is never evaluated in float32. Scratch is sized by `arm_resize_nearest_neighbor_f16_get_buffer_size()` (same query as f32).

:::

**Parameters**

| Name | Type | Direction | Description |
| --- | --- | --- | --- |
| ctx | const cmsis_nn_context * | in | Scratch context. ctx->buf must be non-NULL and 4-byte aligned, and ctx->size at least arm_resize_nearest_neighbor_f32_get_buffer_size(output_shape); the kernel writes the x/y index maps here and does not read them after returning. |
| resize_params | const cmsis_nn_resize_params * | in | align_corners / half_pixel_centers. |
| input_shape | const cmsis_nn_dims * | in | Input tensor dimensions in NHWC format; every dimension must be >= 1. |
| input_data | const float16_t * | in | Input tensor data. Must not overlap `output_data`. |
| output_size_shape | const cmsis_nn_dims * | in | Dimensions of the output-size tensor; must hold exactly 2 elements. |
| output_size_data | const int32_t * | in | Output size as [output_height, output_width], both >= 1. |
| output_shape | const cmsis_nn_dims * | in | Output tensor dimensions in NHWC format; n and c must equal the input's and h/w must equal `output_size_data`. |
| output_data | float16_t * | out | Output tensor data. |

**Returns**

| Name | Type | Description |
| --- | --- | --- |
|  |  | ARM_CMSIS_NN_SUCCESS, or ARM_CMSIS_NN_ARG_ERROR when any constraint above fails (including a NULL pointer argument); nothing is written on ARG_ERROR. |

Source: `Include/arm_nnfunctions_flt.h:3302`