tesseract 4.1.1
Loading...
Searching...
No Matches
intsimdmatrix.cpp
Go to the documentation of this file.
1
2// File: intsimdmatrix.cpp
3// Description: Base class for 8-bit int SIMD matrix multipliers.
4// Author: Ray Smith
5// Created: Tue Aug 15 08:01:32 PST 2017
6//
7// (C) Copyright 2017, Google Inc.
8// Licensed under the Apache License, Version 2.0 (the "License");
9// you may not use this file except in compliance with the License.
10// You may obtain a copy of the License at
11// http://www.apache.org/licenses/LICENSE-2.0
12// Unless required by applicable law or agreed to in writing, software
13// distributed under the License is distributed on an "AS IS" BASIS,
14// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15// See the License for the specific language governing permissions and
16// limitations under the License.
18
19#include "intsimdmatrix.h"
20#include "genericvector.h" // for GenericVector
21#include "matrix.h" // for GENERIC_2D_ARRAY
22#include "simddetect.h" // for SIMDDetect
23
24namespace tesseract {
25
26const IntSimdMatrix* IntSimdMatrix::intSimdMatrix = nullptr;
27
28// Computes a reshaped copy of the weight matrix w.
30 std::vector<int8_t>& shaped_w) const {
31 const int num_out = w.dim1();
32 const int num_in = w.dim2() - 1;
33 // The rounded-up sizes of the reshaped weight matrix, excluding biases.
34 int rounded_num_in = Roundup(num_in, num_inputs_per_group_);
35 int rounded_num_out = RoundOutputs(num_out);
36 // Add the bias and compute the required size.
37 shaped_w.resize((rounded_num_in + 1) * rounded_num_out, 0);
38 int shaped_index = 0;
39 int output = 0;
40 // Each number of registers needs a different format! Iterates over the
41 // different numbers of registers (each a power of 2).
42 for (int num_registers = max_output_registers_; num_registers >= 1;
43 num_registers /= 2) {
44 // The number of outputs that we will generate with this many registers.
45 int num_outputs_per_register_set =
46 num_registers * num_outputs_per_register_;
47 // Use the max number of registers until we have to go fewer.
48 while (output + num_outputs_per_register_set <= rounded_num_out) {
49 // Accumulating outputs in registers saves iterating over the inputs, so
50 // we only have to do it once per output register set.
51 for (int input = 0; input < num_in; input += num_inputs_per_group_) {
52 // Iterate over the number of outputs in a register set.
53 for (int j = 0; j < num_outputs_per_register_set; ++j) {
54 // Inner-most loop corresponds to the number of inputs in an input
55 // group.
56 for (int i = 0; i < num_inputs_per_group_; ++i) {
57 int8_t weight = 0;
58 if (output + j < num_out && input + i < num_in)
59 weight = w(output + j, input + i);
60 shaped_w[shaped_index++] = weight;
61 }
62 }
63 }
64 // Append the bias weights for the register set.
65 for (int j = 0; j < num_outputs_per_register_set; ++j) {
66 int8_t weight = 0;
67 if (output + j < num_out) weight = w(output + j, num_in);
68 shaped_w[shaped_index++] = weight;
69 }
70 output += num_outputs_per_register_set;
71 }
72 }
73}
74
75// Computes matrix.vector v = Wu.
76// u is of size W.dim2() - 1 and the output v is of size W.dim1().
77// u is imagined to have an extra element at the end with value 1, to
78// implement the bias, but it doesn't actually have it.
80 const GenericVector<double>& scales,
81 const int8_t* u, double* v) {
82 int num_out = w.dim1();
83 int num_in = w.dim2() - 1;
84 // Base implementation.
85 for (int i = 0; i < num_out; ++i) {
86 const int8_t* wi = w[i];
87 int total = 0;
88 for (int j = 0; j < num_in; ++j) total += wi[j] * u[j];
89 // Add in the bias and correct for integer values.
90 v[i] = (static_cast<double>(total) / INT8_MAX + wi[num_in]) * scales[i];
91 }
92}
93
94} // namespace tesseract
int dim2() const
Definition: matrix.h:210
int dim1() const
Definition: matrix.h:209
static void MatrixDotVector(const GENERIC_2D_ARRAY< int8_t > &w, const GenericVector< double > &scales, const int8_t *u, double *v)
int RoundOutputs(int size) const
Definition: intsimdmatrix.h:73
static int Roundup(int input, int factor)
Definition: intsimdmatrix.h:87
static const IntSimdMatrix * intSimdMatrix
void Init(const GENERIC_2D_ARRAY< int8_t > &w, std::vector< int8_t > &shaped_w) const