//
// This confidential and proprietary software may be used only as
// authorised by a licensing agreement from ARM Limited
// (C) COPYRIGHT 2020-2024 ARM Limited
// ALL RIGHTS RESERVED
// The entire notice above must be reproduced on all authorised
// copies and copies may only be made to the extent permitted
// by a licensing agreement from ARM Limited.

// Convert tensor index coordinates to an element offset
size_t tensor_index_to_offset(shape_t shape, shape_t index) {
    size_t size = tensor_size(shape);  // check tensor shape is valid
    size_t offset = 0;
    for (int32_t i = 0; i < rank(shape); i++) {
        REQUIRE(index[i] >= 0 && index[i] < shape[i]);
        offset = offset * shape[i] + index[i];
    }
    return offset;
}

// Convert an element offset to tensor index coordinates
shape_t tensor_offset_to_index(shape_t shape, size_t offset) {
    size_t size = tensor_size(shape);  // check tensor shape is valid
    REQUIRE(offset < size);
    shape_t index(rank(shape));    // index has rank(shape) indicies
    for(int32_t i = rank(shape) - 1; i >= 0; i--) {
        index[i] = offset % shape[i];
        offset /= shape[i];
    }
    return index;
}

// Check the tensor shape is valid and return the tensor size in elements
size_t tensor_size(shape_t shape) {
    size_t size = 1;
    for (int32_t i = 0; i < rank(shape); i++) {
        REQUIRE(1 <= shape[i] && shape[i] <= maximum<size_t> / size);
        size *= shape[i];
    }
    return size;
}

// Return the size of the tensor in the given axis
// For a rank=0 tensor, returns 1 for all axes
size_t shape_dim(shape_t shape, int axis) {
    return (axis >= rank(shape)) ? 1 : shape[axis];
}