1// Copyright 2015 The Gemmlowp Authors. All Rights Reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15// bit_depth.h: defines the settins controlling LHS/RHS bit depth
16
17#ifndef GEMMLOWP_PUBLIC_BIT_DEPTH_H_
18#define GEMMLOWP_PUBLIC_BIT_DEPTH_H_
19
20namespace gemmlowp {
21
22// The range of allowed values for an operand.
23template <int tMinValue, int tMaxValue>
24struct OperandRange {
25  static const int kMinValue = tMinValue;
26  static const int kMaxValue = tMaxValue;
27  static_assert(0 <= kMinValue, "");
28  static_assert(kMinValue < kMaxValue, "");
29  static_assert(kMaxValue <= 255, "");
30};
31
32using Uint8Range = OperandRange<0, 255>;
33using Uint8RangeExcludingZero = OperandRange<1, 255>;
34
35template <typename tLhsRange, typename tRhsRange>
36struct BitDepthParams {
37  using LhsRange = tLhsRange;
38  using RhsRange = tRhsRange;
39};
40
41// Default: LHS and RHS are 8bit.
42using DefaultL8R8BitDepthParams = BitDepthParams<Uint8Range, Uint8Range>;
43
44// Variant: LHS may not take the value 0. This allows using
45// faster kernels using signed arithmetic, see
46// NEON_64bit_GEMM_Int8Operands_Int32Accumulators_AccumTwoWithin16Bits
47using L8R8WithLhsNonzeroBitDepthParams =
48    BitDepthParams<Uint8RangeExcludingZero, Uint8Range>;
49
50// Deprecated: when gemmlowp used to allow requantizing 8bit
51// inputs to less-than-8-bit depths, the public setting allowing
52// that was DefaultL7R5BitDepthParams. That requantization
53// feature has been removed, but as the whole point of that
54// requantization was to make less-than-8-bit an internal
55// optimization without any impact on the API (other than lowering
56// accuracy), we can temporarily support users who were using it
57// by mapping it to the default 8bit behavior.
58using DefaultL7R5BitDepthParams = DefaultL8R8BitDepthParams;
59
60}  // namespace gemmlowp
61
62#endif  // GEMMLOWP_PUBLIC_BIT_DEPTH_H_
63