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<html><!-- Created using the cpp_pretty_printer from the dlib C++ library. See http://dlib.net for updates. --><head><title>dlib C++ Library - cuda_utils.h</title></head><body bgcolor='white'><pre>
<font color='#009900'>// Copyright (C) 2015 Davis E. King ([email protected])
</font><font color='#009900'>// License: Boost Software License See LICENSE.txt for the full license.
</font><font color='#0000FF'>#ifndef</font> DLIB_CUDA_UtILS_H_
<font color='#0000FF'>#define</font> DLIB_CUDA_UtILS_H_
<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='../algs.h.html'>../algs.h</a>"
<font color='#0000FF'>#ifndef</font> DLIB_USE_CUDA
<font color='#0000FF'>#error</font> "<font color='#CC0000'>This file shouldn't be #included unless DLIB_USE_CUDA is #defined</font>"
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='cuda_errors.h.html'>cuda_errors.h</a>"
<font color='#0000FF'>#include</font> <font color='#5555FF'><</font>cmath<font color='#5555FF'>></font>
<font color='#0000FF'>#include</font> <font color='#5555FF'><</font>cuda_runtime.h<font color='#5555FF'>></font>
<font color='#0000FF'>#include</font> <font color='#5555FF'><</font>sstream<font color='#5555FF'>></font>
<font color='#0000FF'>#include</font> <font color='#5555FF'><</font>iostream<font color='#5555FF'>></font>
<font color='#0000FF'>#include</font> <font color='#5555FF'><</font>memory<font color='#5555FF'>></font>
<font color='#0000FF'>#include</font> <font color='#5555FF'><</font>vector<font color='#5555FF'>></font>
<font color='#0000FF'>#include</font> <font color='#5555FF'><</font>type_traits<font color='#5555FF'>></font>
<font color='#009900'>// Check the return value of a call to the CUDA runtime for an error condition.
</font><font color='#0000FF'>#define</font> CHECK_CUDA<font face='Lucida Console'>(</font>call<font face='Lucida Console'>)</font> \
<font color='#0000FF'>do</font><b>{</b> \
<font color='#0000FF'>const</font> cudaError_t error <font color='#5555FF'>=</font> call; \
<font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>error <font color='#5555FF'>!</font><font color='#5555FF'>=</font> cudaSuccess<font face='Lucida Console'>)</font> \
<b>{</b> \
std::ostringstream sout; \
sout <font color='#5555FF'><</font><font color='#5555FF'><</font> "<font color='#CC0000'>Error while calling </font>" <font color='#5555FF'><</font><font color='#5555FF'><</font> #call <font color='#5555FF'><</font><font color='#5555FF'><</font> "<font color='#CC0000'> in file </font>" <font color='#5555FF'><</font><font color='#5555FF'><</font> __FILE__ <font color='#5555FF'><</font><font color='#5555FF'><</font> "<font color='#CC0000'>:</font>" <font color='#5555FF'><</font><font color='#5555FF'><</font> __LINE__ <font color='#5555FF'><</font><font color='#5555FF'><</font> "<font color='#CC0000'>. </font>";\
sout <font color='#5555FF'><</font><font color='#5555FF'><</font> "<font color='#CC0000'>code: </font>" <font color='#5555FF'><</font><font color='#5555FF'><</font> error <font color='#5555FF'><</font><font color='#5555FF'><</font> "<font color='#CC0000'>, reason: </font>" <font color='#5555FF'><</font><font color='#5555FF'><</font> <font color='#BB00BB'>cudaGetErrorString</font><font face='Lucida Console'>(</font>error<font face='Lucida Console'>)</font>;\
<font color='#0000FF'>throw</font> dlib::<font color='#BB00BB'>cuda_error</font><font face='Lucida Console'>(</font>sout.<font color='#BB00BB'>str</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>; \
<b>}</b> \
<b>}</b><font color='#0000FF'>while</font><font face='Lucida Console'>(</font><font color='#979000'>false</font><font face='Lucida Console'>)</font>
<font color='#009900'>// ----------------------------------------------------------------------------------------
</font>
<font color='#0000FF'>#ifdef</font> __CUDACC__
<font color='#0000FF'>namespace</font> dlib
<b>{</b>
<font color='#0000FF'>namespace</font> cuda
<b>{</b>
<font color='#009900'>// ------------------------------------------------------------------------------------
</font>
__inline__ __device__ <font color='#0000FF'><u>size_t</u></font> <b><a name='pack_idx'></a>pack_idx</b> <font face='Lucida Console'>(</font>
<font color='#0000FF'><u>size_t</u></font> dim_size3,
<font color='#0000FF'><u>size_t</u></font> dim_size2,
<font color='#0000FF'><u>size_t</u></font> dim_size1,
<font color='#0000FF'><u>size_t</u></font> idx4,
<font color='#0000FF'><u>size_t</u></font> idx3,
<font color='#0000FF'><u>size_t</u></font> idx2,
<font color='#0000FF'><u>size_t</u></font> idx1
<font face='Lucida Console'>)</font>
<font color='#009900'>/*!
ensures
- Converts a 4D array index into a 1D index assuming row major layout. To
understand precisely what this function does, imagine we had an array
declared like this:
int ARRAY[anything][dim_size3][dim_size2][dim_size1];
Then we could index it like this:
ARRAY[idx4][idx3][idx2][idx1]
or equivalently like this:
((int*)ARRAY)[pack_idx(dim_size3,dim_size2,dim_size1, idx4,idx3,idx2,idx1)]
!*/</font>
<b>{</b>
<font color='#0000FF'>return</font> <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>idx4<font color='#5555FF'>*</font>dim_size3 <font color='#5555FF'>+</font> idx3<font face='Lucida Console'>)</font><font color='#5555FF'>*</font>dim_size2 <font color='#5555FF'>+</font> idx2<font face='Lucida Console'>)</font><font color='#5555FF'>*</font>dim_size1 <font color='#5555FF'>+</font> idx1;
<b>}</b>
__inline__ __device__ <font color='#0000FF'><u>void</u></font> <b><a name='unpack_idx'></a>unpack_idx</b> <font face='Lucida Console'>(</font>
<font color='#0000FF'><u>size_t</u></font> idx,
<font color='#0000FF'><u>size_t</u></font> dim_size3,
<font color='#0000FF'><u>size_t</u></font> dim_size2,
<font color='#0000FF'><u>size_t</u></font> dim_size1,
<font color='#0000FF'><u>size_t</u></font><font color='#5555FF'>&</font> idx4,
<font color='#0000FF'><u>size_t</u></font><font color='#5555FF'>&</font> idx3,
<font color='#0000FF'><u>size_t</u></font><font color='#5555FF'>&</font> idx2,
<font color='#0000FF'><u>size_t</u></font><font color='#5555FF'>&</font> idx1
<font face='Lucida Console'>)</font>
<font color='#009900'>/*!
ensures
- This function computes the inverse of pack_idx(). Therefore,
if PACKED == pack_idx(dim_size3,dim_size2,dim_size1, idx4,idx3,idx2,idx1)
then unpack_idx(PACKED,dim_size3,dim_size2,dim_size1, IDX4,IDX3,IDX2,IDX1)
results in:
- IDX1 == idx1
- IDX2 == idx2
- IDX3 == idx3
- IDX4 == idx4
!*/</font>
<b>{</b>
idx1 <font color='#5555FF'>=</font> idx<font color='#5555FF'>%</font>dim_size1;
idx <font color='#5555FF'>/</font><font color='#5555FF'>=</font> dim_size1;
idx2 <font color='#5555FF'>=</font> idx<font color='#5555FF'>%</font>dim_size2;
idx <font color='#5555FF'>/</font><font color='#5555FF'>=</font> dim_size2;
idx3 <font color='#5555FF'>=</font> idx<font color='#5555FF'>%</font>dim_size3;
idx <font color='#5555FF'>/</font><font color='#5555FF'>=</font> dim_size3;
idx4 <font color='#5555FF'>=</font> idx;
<b>}</b>
<font color='#009900'>// ------------------------------------------------------------------------------------
</font>
<font color='#009900'>// This function is from the article:
</font> <font color='#009900'>// http://devblogs.nvidia.com/parallelforall/faster-parallel-reductions-kepler/
</font> __inline__ __device__ <font color='#0000FF'><u>float</u></font> <b><a name='warp_reduce_sum'></a>warp_reduce_sum</b><font face='Lucida Console'>(</font><font color='#0000FF'><u>float</u></font> val<font face='Lucida Console'>)</font>
<b>{</b>
<font color='#0000FF'>for</font> <font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font> offset <font color='#5555FF'>=</font> warpSize<font color='#5555FF'>/</font><font color='#979000'>2</font>; offset <font color='#5555FF'>></font> <font color='#979000'>0</font>; offset <font color='#5555FF'>/</font><font color='#5555FF'>=</font> <font color='#979000'>2</font><font face='Lucida Console'>)</font>
<font color='#0000FF'>#if</font> CUDART_VERSION <font color='#5555FF'>></font><font color='#5555FF'>=</font> <font color='#979000'>9000</font>
val <font color='#5555FF'>+</font><font color='#5555FF'>=</font> <font color='#BB00BB'>__shfl_down_sync</font><font face='Lucida Console'>(</font><font color='#979000'>0xFFFFFFFF</font>,val, offset<font face='Lucida Console'>)</font>;
<font color='#0000FF'>#else</font>
val <font color='#5555FF'>+</font><font color='#5555FF'>=</font> <font color='#BB00BB'>__shfl_down</font><font face='Lucida Console'>(</font>val, offset<font face='Lucida Console'>)</font>;
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>return</font> val;
<b>}</b>
__inline__ __device__ <font color='#0000FF'><u>bool</u></font> <b><a name='is_first_thread_in_warp'></a>is_first_thread_in_warp</b><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font>
<b>{</b>
<font color='#0000FF'>return</font> <font face='Lucida Console'>(</font>threadIdx.x <font color='#5555FF'>&</font> <font face='Lucida Console'>(</font>warpSize <font color='#5555FF'>-</font> <font color='#979000'>1</font><font face='Lucida Console'>)</font><font face='Lucida Console'>)</font> <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font>;
<b>}</b>
__inline__ __device__ <font color='#0000FF'><u>void</u></font> <b><a name='warp_reduce_atomic_add'></a>warp_reduce_atomic_add</b><font face='Lucida Console'>(</font>
<font color='#0000FF'><u>float</u></font><font color='#5555FF'>&</font> out,
<font color='#0000FF'><u>float</u></font> val
<font face='Lucida Console'>)</font>
<font color='#009900'>/*!
ensures
- Atomically adds all the val variables in the current warp to out.
See this page for an extended discussion:
http://devblogs.nvidia.com/parallelforall/faster-parallel-reductions-kepler/
!*/</font>
<b>{</b>
val <font color='#5555FF'>=</font> <font color='#BB00BB'>warp_reduce_sum</font><font face='Lucida Console'>(</font>val<font face='Lucida Console'>)</font>;
<font color='#0000FF'>if</font> <font face='Lucida Console'>(</font><font color='#BB00BB'>is_first_thread_in_warp</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>
<font color='#BB00BB'>atomicAdd</font><font face='Lucida Console'>(</font><font color='#5555FF'>&</font>out, val<font face='Lucida Console'>)</font>;
<b>}</b>
<font color='#009900'>// ------------------------------------------------------------------------------------
</font>
<font color='#0000FF'>struct</font> <b><a name='max_jobs'></a>max_jobs</b>
<b>{</b>
<b><a name='max_jobs'></a>max_jobs</b><font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font> x<font face='Lucida Console'>)</font> : num_x<font face='Lucida Console'>(</font>x<font face='Lucida Console'>)</font> <b>{</b><b>}</b>
<b><a name='max_jobs'></a>max_jobs</b><font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font> x, <font color='#0000FF'><u>int</u></font> y<font face='Lucida Console'>)</font> : num_x<font face='Lucida Console'>(</font>x<font face='Lucida Console'>)</font>, num_y<font face='Lucida Console'>(</font>y<font face='Lucida Console'>)</font> <b>{</b><b>}</b>
<font color='#0000FF'><u>int</u></font> num_x;
<font color='#0000FF'><u>int</u></font> num_y <font color='#5555FF'>=</font> <font color='#979000'>1</font>;
<b>}</b>;
<font color='#0000FF'>template</font> <font color='#5555FF'><</font><font color='#0000FF'>typename</font> Kernel, <font color='#0000FF'>typename</font>... T<font color='#5555FF'>></font>
<font color='#0000FF'><u>void</u></font> <b><a name='launch_kernel'></a>launch_kernel</b> <font face='Lucida Console'>(</font>
Kernel K,
T ...args
<font face='Lucida Console'>)</font>
<font color='#009900'>/*!
ensures
- launches the given kernel K(args...). The point of this function is to
automatically set the kernel launch parameters to something reasonable
based on the properties of the kernel and the current GPU card.
!*/</font>
<b>{</b>
<font color='#0000FF'><u>int</u></font> num_blocks, num_threads;
<font color='#BB00BB'>CHECK_CUDA</font><font face='Lucida Console'>(</font><font color='#BB00BB'>cudaOccupancyMaxPotentialBlockSize</font><font face='Lucida Console'>(</font><font color='#5555FF'>&</font>num_blocks,<font color='#5555FF'>&</font>num_threads,K<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>;
K<font color='#5555FF'><</font><font color='#5555FF'><</font><font color='#5555FF'><</font>num_blocks,num_threads<font color='#5555FF'>></font><font color='#5555FF'>></font><font color='#5555FF'>></font><font face='Lucida Console'>(</font>args...<font face='Lucida Console'>)</font>;
<b>}</b>
<font color='#0000FF'>template</font> <font color='#5555FF'><</font><font color='#0000FF'>typename</font> Kernel, <font color='#0000FF'>typename</font>... T<font color='#5555FF'>></font>
<font color='#0000FF'><u>void</u></font> <b><a name='launch_kernel'></a>launch_kernel</b> <font face='Lucida Console'>(</font>
Kernel K,
max_jobs m,
T ...args
<font face='Lucida Console'>)</font>
<font color='#009900'>/*!
ensures
- This function is just like launch_kernel(K,args...) except that you can
additionally supply a max_jobs number that tells it how many possible
total threads could be used. This is useful when launching potentially
small jobs that might not need the number of threads suggested by
launch_kernel().
!*/</font>
<b>{</b>
<font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>m.num_x <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>|</font><font color='#5555FF'>|</font> m.num_y <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font><font face='Lucida Console'>)</font>
<font color='#0000FF'>return</font>;
<font color='#0000FF'><u>int</u></font> num_blocks, num_threads;
<font color='#BB00BB'>CHECK_CUDA</font><font face='Lucida Console'>(</font><font color='#BB00BB'>cudaOccupancyMaxPotentialBlockSize</font><font face='Lucida Console'>(</font><font color='#5555FF'>&</font>num_blocks,<font color='#5555FF'>&</font>num_threads,K<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>;
<font color='#009900'>// Check if the job is really small and we don't really need to launch a kernel
</font> <font color='#009900'>// with this many blocks and threads.
</font> <font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>num_blocks<font color='#5555FF'>*</font>num_threads <font color='#5555FF'>></font> m.num_x<font color='#5555FF'>*</font>m.num_y<font face='Lucida Console'>)</font>
num_blocks <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font>m.num_x<font color='#5555FF'>*</font>m.num_y<font color='#5555FF'>+</font>num_threads<font color='#5555FF'>-</font><font color='#979000'>1</font><font face='Lucida Console'>)</font><font color='#5555FF'>/</font>num_threads;
<font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>m.num_y <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>1</font><font face='Lucida Console'>)</font>
<b>{</b>
K<font color='#5555FF'><</font><font color='#5555FF'><</font><font color='#5555FF'><</font>num_blocks,num_threads<font color='#5555FF'>></font><font color='#5555FF'>></font><font color='#5555FF'>></font><font face='Lucida Console'>(</font>args...<font face='Lucida Console'>)</font>;
<b>}</b>
<font color='#0000FF'>else</font>
<b>{</b>
<font color='#009900'>/*
In general, the reason m.num_y!=1 (i.e. the reason you are in this
code path) is because we are using nested grid-stride loops. There are
two important things to note about what we are doing here. To
illustrate them we will talk about this little CUDA code snippet:
// initialize out before we begin.
for (auto i : grid_stride_range_y(0, nr))
for (auto j : grid_stride_range(0, 1))
out[i] = 0;
__syncthreads(); // synchronize threads in block
// loop over some 2D thing and sum and store things into out.
for (auto i : grid_stride_range_y(0, nr))
{
float temp = 0;
for (auto j : grid_stride_range(0, nc))
temp += whatever[i*nc+j];
// store the sum into out[i]
warp_reduce_atomic_add(out[i], temp);
}
First, we make sure the number of x threads is a multiple of 32 so that
you can use warp_reduce_atomic_add() inside the y loop.
Second, we put the x block size to 1 so inter-block synchronization is
easier. For example, if the number of x blocks wasn't 1 the above code
would have a race condition in it. This is because the execution of
out[i]=0 would be done by blocks with blockIdx.x==0, but then in the
second set of loops, *all* the x blocks use out[i]. Since
__syncthreads() doesn't do any synchronization between blocks some of
the blocks might begin before the out[i]=0 statements finished and that
would be super bad.
*/</font>
<font color='#009900'>// Try and make sure that the ratio of x to y threads is reasonable based
</font> <font color='#009900'>// on the respective size of our loops.
</font> <font color='#0000FF'><u>int</u></font> x_threads <font color='#5555FF'>=</font> <font color='#979000'>32</font>;
<font color='#0000FF'><u>int</u></font> y_threads <font color='#5555FF'>=</font> num_threads<font color='#5555FF'>/</font><font color='#979000'>32</font>;
<font color='#0000FF'>const</font> <font color='#0000FF'><u>int</u></font> ratio <font color='#5555FF'>=</font> <font color='#0000FF'>static_cast</font><font color='#5555FF'><</font><font color='#0000FF'><u>int</u></font><font color='#5555FF'>></font><font face='Lucida Console'>(</font>std::<font color='#BB00BB'>round</font><font face='Lucida Console'>(</font><font color='#BB00BB'>put_in_range</font><font face='Lucida Console'>(</font><font color='#979000'>1</font>, y_threads, m.num_x<font color='#5555FF'>/</font><font face='Lucida Console'>(</font><font color='#0000FF'><u>double</u></font><font face='Lucida Console'>)</font>m.num_y<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>;
x_threads <font color='#5555FF'>*</font><font color='#5555FF'>=</font> ratio;
y_threads <font color='#5555FF'>/</font><font color='#5555FF'>=</font> ratio;
dim3 <font color='#BB00BB'>blocks</font><font face='Lucida Console'>(</font><font color='#979000'>1</font>,num_blocks<font face='Lucida Console'>)</font>;
dim3 <font color='#BB00BB'>threads</font><font face='Lucida Console'>(</font>x_threads,y_threads<font face='Lucida Console'>)</font>;
K<font color='#5555FF'><</font><font color='#5555FF'><</font><font color='#5555FF'><</font>blocks,threads<font color='#5555FF'>></font><font color='#5555FF'>></font><font color='#5555FF'>></font><font face='Lucida Console'>(</font>args...<font face='Lucida Console'>)</font>;
<b>}</b>
<b>}</b>
<font color='#009900'>// ------------------------------------------------------------------------------------
</font>
<font color='#0000FF'>class</font> <b><a name='grid_stride_range'></a>grid_stride_range</b>
<b>{</b>
<font color='#009900'>/*!
WHAT THIS OBJECT REPRESENTS
This is a tool for making a for loop that loops over an entire block of
memory inside a kernel, but doing so in a way that parallelizes
appropriately across all the threads in a kernel launch. For example,
the following kernel would add the vector a to the vector b and store
the output in out (assuming all vectors are of dimension n):
__global__ void add_arrays(
const float* a,
const float* b,
float* out,
size_t n
)
{
for (auto i : grid_stride_range(0, n))
{
out[i] = a[i]+b[i];
}
}
!*/</font>
<font color='#0000FF'>public</font>:
__device__ <b><a name='grid_stride_range'></a>grid_stride_range</b><font face='Lucida Console'>(</font>
<font color='#0000FF'><u>size_t</u></font> ibegin_,
<font color='#0000FF'><u>size_t</u></font> iend_
<font face='Lucida Console'>)</font> :
ibegin<font face='Lucida Console'>(</font>ibegin_<font face='Lucida Console'>)</font>,
iend<font face='Lucida Console'>(</font>iend_<font face='Lucida Console'>)</font>
<b>{</b><b>}</b>
<font color='#0000FF'>class</font> <b><a name='iterator'></a>iterator</b>
<b>{</b>
<font color='#0000FF'>public</font>:
__device__ <b><a name='iterator'></a>iterator</b><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> <b>{</b><b>}</b>
__device__ <b><a name='iterator'></a>iterator</b><font face='Lucida Console'>(</font><font color='#0000FF'><u>size_t</u></font> pos_<font face='Lucida Console'>)</font> : pos<font face='Lucida Console'>(</font>pos_<font face='Lucida Console'>)</font> <b>{</b><b>}</b>
__device__ <font color='#0000FF'><u>size_t</u></font> <b><a name='operator'></a>operator</b><font color='#5555FF'>*</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> <font color='#0000FF'>const</font>
<b>{</b>
<font color='#0000FF'>return</font> pos;
<b>}</b>
__device__ iterator<font color='#5555FF'>&</font> <b><a name='operator'></a>operator</b><font color='#5555FF'>+</font><font color='#5555FF'>+</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font>
<b>{</b>
pos <font color='#5555FF'>+</font><font color='#5555FF'>=</font> gridDim.x <font color='#5555FF'>*</font> blockDim.x;
<font color='#0000FF'>return</font> <font color='#5555FF'>*</font><font color='#0000FF'>this</font>;
<b>}</b>
__device__ <font color='#0000FF'><u>bool</u></font> <b><a name='operator'></a>operator</b><font color='#5555FF'>!</font><font color='#5555FF'>=</font><font face='Lucida Console'>(</font><font color='#0000FF'>const</font> iterator<font color='#5555FF'>&</font> item<font face='Lucida Console'>)</font> <font color='#0000FF'>const</font>
<b>{</b> <font color='#0000FF'>return</font> pos <font color='#5555FF'><</font> item.pos; <b>}</b>
<font color='#0000FF'>private</font>:
<font color='#0000FF'><u>size_t</u></font> pos;
<b>}</b>;
__device__ iterator <b><a name='begin'></a>begin</b><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> <font color='#0000FF'>const</font>
<b>{</b>
<font color='#0000FF'>return</font> <font color='#BB00BB'>iterator</font><font face='Lucida Console'>(</font>ibegin<font color='#5555FF'>+</font>blockDim.x <font color='#5555FF'>*</font> blockIdx.x <font color='#5555FF'>+</font> threadIdx.x<font face='Lucida Console'>)</font>;
<b>}</b>
__device__ iterator <b><a name='end'></a>end</b><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> <font color='#0000FF'>const</font>
<b>{</b>
<font color='#0000FF'>return</font> <font color='#BB00BB'>iterator</font><font face='Lucida Console'>(</font>iend<font face='Lucida Console'>)</font>;
<b>}</b>
<font color='#0000FF'>private</font>:
<font color='#0000FF'><u>size_t</u></font> ibegin;
<font color='#0000FF'><u>size_t</u></font> iend;
<b>}</b>;
<font color='#009900'>// ------------------------------------------------------------------------------------
</font>
<font color='#0000FF'>class</font> <b><a name='grid_stride_range_y'></a>grid_stride_range_y</b>
<b>{</b>
<font color='#009900'>/*!
WHAT THIS OBJECT REPRESENTS
This object is just like grid_stride_range except that it looks at
CUDA's y thread index (e.g. threadIdx.y) instead of the x index.
Therefore, if you launch a cuda kernel with a statement like:
dim3 blocks(1,10);
dim3 threads(32,32); // You need to have x and y not equal to 1 to get parallelism over both loops.
add_arrays<<<blocks,threads>>>(a,b,out,nr,nc);
You can perform a nested 2D parallel for loop rather than doing just a
1D for loop.
So the code in the kernel would look like this if you wanted to add two
2D matrices:
__global__ void add_arrays(
const float* a,
const float* b,
float* out,
size_t nr,
size_t nc
)
{
for (auto r : grid_stride_range_y(0, nr))
{
for (auto c : grid_stride_range(0, nc))
{
auto i = r*nc+c;
out[i] = a[i]+b[i];
}
}
}
!*/</font>
<font color='#0000FF'>public</font>:
__device__ <b><a name='grid_stride_range_y'></a>grid_stride_range_y</b><font face='Lucida Console'>(</font>
<font color='#0000FF'><u>size_t</u></font> ibegin_,
<font color='#0000FF'><u>size_t</u></font> iend_
<font face='Lucida Console'>)</font> :
ibegin<font face='Lucida Console'>(</font>ibegin_<font face='Lucida Console'>)</font>,
iend<font face='Lucida Console'>(</font>iend_<font face='Lucida Console'>)</font>
<b>{</b><b>}</b>
<font color='#0000FF'>class</font> <b><a name='iterator'></a>iterator</b>
<b>{</b>
<font color='#0000FF'>public</font>:
__device__ <b><a name='iterator'></a>iterator</b><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> <b>{</b><b>}</b>
__device__ <b><a name='iterator'></a>iterator</b><font face='Lucida Console'>(</font><font color='#0000FF'><u>size_t</u></font> pos_<font face='Lucida Console'>)</font> : pos<font face='Lucida Console'>(</font>pos_<font face='Lucida Console'>)</font> <b>{</b><b>}</b>
__device__ <font color='#0000FF'><u>size_t</u></font> <b><a name='operator'></a>operator</b><font color='#5555FF'>*</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> <font color='#0000FF'>const</font>
<b>{</b>
<font color='#0000FF'>return</font> pos;
<b>}</b>
__device__ iterator<font color='#5555FF'>&</font> <b><a name='operator'></a>operator</b><font color='#5555FF'>+</font><font color='#5555FF'>+</font><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font>
<b>{</b>
pos <font color='#5555FF'>+</font><font color='#5555FF'>=</font> gridDim.y <font color='#5555FF'>*</font> blockDim.y;
<font color='#0000FF'>return</font> <font color='#5555FF'>*</font><font color='#0000FF'>this</font>;
<b>}</b>
__device__ <font color='#0000FF'><u>bool</u></font> <b><a name='operator'></a>operator</b><font color='#5555FF'>!</font><font color='#5555FF'>=</font><font face='Lucida Console'>(</font><font color='#0000FF'>const</font> iterator<font color='#5555FF'>&</font> item<font face='Lucida Console'>)</font> <font color='#0000FF'>const</font>
<b>{</b> <font color='#0000FF'>return</font> pos <font color='#5555FF'><</font> item.pos; <b>}</b>
<font color='#0000FF'>private</font>:
<font color='#0000FF'><u>size_t</u></font> pos;
<b>}</b>;
__device__ iterator <b><a name='begin'></a>begin</b><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> <font color='#0000FF'>const</font>
<b>{</b>
<font color='#0000FF'>return</font> <font color='#BB00BB'>iterator</font><font face='Lucida Console'>(</font>ibegin<font color='#5555FF'>+</font>blockDim.y <font color='#5555FF'>*</font> blockIdx.y <font color='#5555FF'>+</font> threadIdx.y<font face='Lucida Console'>)</font>;
<b>}</b>
__device__ iterator <b><a name='end'></a>end</b><font face='Lucida Console'>(</font><font face='Lucida Console'>)</font> <font color='#0000FF'>const</font>
<b>{</b>
<font color='#0000FF'>return</font> <font color='#BB00BB'>iterator</font><font face='Lucida Console'>(</font>iend<font face='Lucida Console'>)</font>;
<b>}</b>
<font color='#0000FF'>private</font>:
<font color='#0000FF'><u>size_t</u></font> ibegin;
<font color='#0000FF'><u>size_t</u></font> iend;
<b>}</b>;
<font color='#009900'>// ------------------------------------------------------------------------------------
</font>
<b>}</b>
<b>}</b>
<font color='#0000FF'>#endif</font> <font color='#009900'>// __CUDACC__
</font>
<font color='#009900'>// ----------------------------------------------------------------------------------------
</font>
<font color='#0000FF'>#endif</font> <font color='#009900'>// DLIB_CUDA_UtILS_H_
</font>
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