# BSD 3-Clause License
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# Copyright (c) 2017 xxxx
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# Copyright 2021 Huawei Technologies Co., Ltd
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# modification, are permitted provided that the following conditions are met:
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# * Redistributions of source code must retain the above copyright notice, this
#   list of conditions and the following disclaimer.
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# ============================================================================

import torch

@torch.jit.script
def slice_helper(x, offset):
    return x[:, -offset: , : ]

@torch.jit.script
def slice_helper2(x: torch.Tensor, start: torch.Tensor, end: torch.Tensor):
    start = start.long()
    end = end.long()
    return x[:, start:end]

@torch.jit.script
def slice_helper3(x, start):
    return x[:, start:]

@torch.jit.script
def get_item(x):
    item = x.detach().item()
    output = torch.tensor(item)
    return output

@torch.jit.script
def get_next_cache_start(required_cache_size: torch.Tensor, xs: torch.Tensor):
    next_cache_start = 0
    if required_cache_size < 0:
        next_cache_start = 0
    elif required_cache_size == 0:
        next_cache_start = xs.size(1)
    else:
        if xs.size(1) - required_cache_size < 0:
            next_cache_start = 0
        else:
            next_cache_start = xs.size(1) - required_cache_size
    return torch.tensor(next_cache_start, dtype=torch.int64)