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// =================================================================================================
// This file is part of the CLBlast project. The project is licensed under Apache Version 2.0. This
// project loosely follows the Google C++ styleguide and uses a tab-size of two spaces and a max-
// width of 100 characters per line.
//
// Author(s):
// Cedric Nugteren <www.cedricnugteren.nl>
//
// This file contains kernels to perform forward or backward substition, as used in the TRSV routine
//
// =================================================================================================
// Enables loading of this file using the C++ pre-processor's #include (C++11 standard raw string
// literal). Comment-out this line for syntax-highlighting when developing.
R"(
// =================================================================================================
#if defined(ROUTINE_TRSV)
__kernel __attribute__((reqd_work_group_size(64, 1, 1)))
void FillVector(const int n, const int inc, const int offset,
__global real* restrict dest, const real_arg arg_value) {
const real value = GetRealArg(arg_value);
const int tid = get_global_id(0);
if (tid < n) {
dest[tid*inc + offset] = value;
}
}
// =================================================================================================
// Parameters set by the tuner or by the database. Here they are given a basic default value in case
// this kernel file is used outside of the CLBlast library.
#ifndef TRSV_BLOCK_SIZE
#define TRSV_BLOCK_SIZE 32 // The block size for forward or backward substition
#endif
// =================================================================================================
__kernel __attribute__((reqd_work_group_size(TRSV_BLOCK_SIZE, 1, 1)))
void trsv_forward(int n,
const __global real *A, const int a_offset, int lda,
__global real *b, const int b_offset, int b_inc,
__global real *x, const int x_offset, int x_inc,
const int is_transposed, const int is_unit_diagonal) {
__local real sx[TRSV_BLOCK_SIZE];
const int tid = get_local_id(0);
if (tid < n) {
sx[tid] = b[tid*b_inc + b_offset];
}
barrier(CLK_LOCAL_MEM_FENCE);
for (int i = 0; i < n; ++i) {
if (tid == 0) {
real sum = sx[i];
for (int j = 0; j < i; ++j) {
real a_value;
if (is_transposed == 0) { a_value = A[i + j*lda + a_offset]; }
else { a_value = A[j + i*lda + a_offset]; }
sum -= a_value * sx[j];
}
sum -= x[i*x_inc + x_offset];
if (is_unit_diagonal == 0) { sum /= A[i + i*lda + a_offset]; }
sx[i] = sum;
}
barrier(CLK_LOCAL_MEM_FENCE);
}
barrier(CLK_LOCAL_MEM_FENCE);
if (tid < n) {
x[tid*x_inc + x_offset] = sx[tid];
}
}
__kernel __attribute__((reqd_work_group_size(TRSV_BLOCK_SIZE, 1, 1)))
void trsv_backward(int n,
const __global real *A, const int a_offset, int lda,
__global real *b, const int b_offset, int b_inc,
__global real *x, const int x_offset, int x_inc,
const int is_trans, const int is_unit_diagonal) {
__local real sx[TRSV_BLOCK_SIZE];
const int tid = get_local_id(0);
if (tid < n) {
sx[tid] = b[tid*b_inc + b_offset];
}
barrier(CLK_LOCAL_MEM_FENCE);
for (int i = n - 1; i >= 0; --i) {
if (tid == 0) {
real sum = sx[i];
for (int j = i + 1; j < n; ++j) {
real a_value;
if (is_trans == 0) { a_value = A[i + j*lda + a_offset]; }
else { a_value = A[j + i*lda + a_offset]; }
sum -= a_value * sx[j];
}
sum -= x[i*x_inc + x_offset];
if (is_unit_diagonal == 0) { sum /= A[i + i*lda + a_offset]; }
sx[i] = sum;
}
barrier(CLK_LOCAL_MEM_FENCE);
}
barrier(CLK_LOCAL_MEM_FENCE);
if (tid < n) {
x[tid*x_inc + x_offset] = sx[tid];
}
}
#endif
// =================================================================================================
// End of the C++11 raw string literal
)"
// =================================================================================================
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