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/******************************************************************************
*
* Project: GDAL Gridding API.
* Purpose: Implementation of GDAL scattered data gridder.
* Author: Even Rouault, <even dot rouault at spatialys.com>
*
******************************************************************************
* Copyright (c) 2013, Even Rouault <even dot rouault at spatialys.com>
*
* SPDX-License-Identifier: MIT
****************************************************************************/
#include "gdalgrid.h"
#include "gdalgrid_priv.h"
#ifdef HAVE_SSE_AT_COMPILE_TIME
#ifdef USE_NEON_OPTIMIZATIONS
#include "include_sse2neon.h"
#else
#include <xmmintrin.h>
#endif
/************************************************************************/
/* GDALGridInverseDistanceToAPower2NoSmoothingNoSearchSSE() */
/************************************************************************/
CPLErr GDALGridInverseDistanceToAPower2NoSmoothingNoSearchSSE(
const void *poOptions, GUInt32 nPoints,
CPL_UNUSED const double *unused_padfX,
CPL_UNUSED const double *unused_padfY,
CPL_UNUSED const double *unused_padfZ, double dfXPoint, double dfYPoint,
double *pdfValue, void *hExtraParamsIn)
{
size_t i = 0;
GDALGridExtraParameters *psExtraParams =
static_cast<GDALGridExtraParameters *>(hExtraParamsIn);
const float *pafX = psExtraParams->pafX;
const float *pafY = psExtraParams->pafY;
const float *pafZ = psExtraParams->pafZ;
const float fEpsilon = 0.0000000000001f;
const float fXPoint = static_cast<float>(dfXPoint);
const float fYPoint = static_cast<float>(dfYPoint);
const __m128 xmm_small = _mm_load1_ps(const_cast<float *>(&fEpsilon));
const __m128 xmm_x = _mm_load1_ps(const_cast<float *>(&fXPoint));
const __m128 xmm_y = _mm_load1_ps(const_cast<float *>(&fYPoint));
__m128 xmm_nominator = _mm_setzero_ps();
__m128 xmm_denominator = _mm_setzero_ps();
int mask = 0;
#if defined(__x86_64) || defined(_M_X64) || defined(USE_NEON_OPTIMIZATIONS)
// This would also work in 32bit mode, but there are only 8 XMM registers
// whereas we have 16 for 64bit.
const size_t LOOP_SIZE = 8;
size_t nPointsRound = (nPoints / LOOP_SIZE) * LOOP_SIZE;
for (i = 0; i < nPointsRound; i += LOOP_SIZE)
{
// rx = pafX[i] - fXPoint
__m128 xmm_rx = _mm_sub_ps(_mm_load_ps(pafX + i), xmm_x);
__m128 xmm_rx_4 = _mm_sub_ps(_mm_load_ps(pafX + i + 4), xmm_x);
// ry = pafY[i] - fYPoint
__m128 xmm_ry = _mm_sub_ps(_mm_load_ps(pafY + i), xmm_y);
__m128 xmm_ry_4 = _mm_sub_ps(_mm_load_ps(pafY + i + 4), xmm_y);
// r2 = rx * rx + ry * ry
__m128 xmm_r2 =
_mm_add_ps(_mm_mul_ps(xmm_rx, xmm_rx), _mm_mul_ps(xmm_ry, xmm_ry));
__m128 xmm_r2_4 = _mm_add_ps(_mm_mul_ps(xmm_rx_4, xmm_rx_4),
_mm_mul_ps(xmm_ry_4, xmm_ry_4));
// invr2 = 1.0f / r2
__m128 xmm_invr2 = _mm_rcp_ps(xmm_r2);
__m128 xmm_invr2_4 = _mm_rcp_ps(xmm_r2_4);
// nominator += invr2 * pafZ[i]
xmm_nominator = _mm_add_ps(
xmm_nominator, _mm_mul_ps(xmm_invr2, _mm_load_ps(pafZ + i)));
xmm_nominator = _mm_add_ps(
xmm_nominator, _mm_mul_ps(xmm_invr2_4, _mm_load_ps(pafZ + i + 4)));
// denominator += invr2
xmm_denominator = _mm_add_ps(xmm_denominator, xmm_invr2);
xmm_denominator = _mm_add_ps(xmm_denominator, xmm_invr2_4);
// if( r2 < fEpsilon)
mask = _mm_movemask_ps(_mm_cmplt_ps(xmm_r2, xmm_small)) |
(_mm_movemask_ps(_mm_cmplt_ps(xmm_r2_4, xmm_small)) << 4);
if (mask)
break;
}
#else
#define LOOP_SIZE 4
size_t nPointsRound = (nPoints / LOOP_SIZE) * LOOP_SIZE;
for (i = 0; i < nPointsRound; i += LOOP_SIZE)
{
__m128 xmm_rx = _mm_sub_ps(_mm_load_ps(pafX + i),
xmm_x); /* rx = pafX[i] - fXPoint */
__m128 xmm_ry = _mm_sub_ps(_mm_load_ps(pafY + i),
xmm_y); /* ry = pafY[i] - fYPoint */
__m128 xmm_r2 =
_mm_add_ps(_mm_mul_ps(xmm_rx, xmm_rx), /* r2 = rx * rx + ry * ry */
_mm_mul_ps(xmm_ry, xmm_ry));
__m128 xmm_invr2 = _mm_rcp_ps(xmm_r2); /* invr2 = 1.0f / r2 */
xmm_nominator =
_mm_add_ps(xmm_nominator, /* nominator += invr2 * pafZ[i] */
_mm_mul_ps(xmm_invr2, _mm_load_ps(pafZ + i)));
xmm_denominator =
_mm_add_ps(xmm_denominator, xmm_invr2); /* denominator += invr2 */
mask = _mm_movemask_ps(
_mm_cmplt_ps(xmm_r2, xmm_small)); /* if( r2 < fEpsilon) */
if (mask)
break;
}
#endif
// Find which i triggered r2 < fEpsilon.
if (mask)
{
for (size_t j = 0; j < LOOP_SIZE; j++)
{
if (mask & (1 << j))
{
(*pdfValue) = double(pafZ[i + j]);
return CE_None;
}
}
}
// Get back nominator and denominator values for XMM registers.
float afNominator[4];
float afDenominator[4];
_mm_storeu_ps(afNominator, xmm_nominator);
_mm_storeu_ps(afDenominator, xmm_denominator);
float fNominator =
afNominator[0] + afNominator[1] + afNominator[2] + afNominator[3];
float fDenominator = afDenominator[0] + afDenominator[1] +
afDenominator[2] + afDenominator[3];
/* Do the few remaining loop iterations */
for (; i < nPoints; i++)
{
const float fRX = pafX[i] - fXPoint;
const float fRY = pafY[i] - fYPoint;
const float fR2 = fRX * fRX + fRY * fRY;
// If the test point is close to the grid node, use the point
// value directly as a node value to avoid singularity.
if (fR2 < 1e-13f)
{
break;
}
else
{
const float fInvR2 = 1.0f / fR2;
fNominator += fInvR2 * pafZ[i];
fDenominator += fInvR2;
}
}
if (i != nPoints)
{
(*pdfValue) = double(pafZ[i]);
}
else if (fDenominator == 0.0f)
{
(*pdfValue) =
static_cast<const GDALGridInverseDistanceToAPowerOptions *>(
poOptions)
->dfNoDataValue;
}
else
{
(*pdfValue) = double(fNominator / fDenominator);
}
return CE_None;
}
#endif /* HAVE_SSE_AT_COMPILE_TIME */
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