opencl_fdtd/fdtd/base.py
2016-03-30 15:00:00 -07:00

76 lines
2.2 KiB
Python

"""
Basic code snippets for opencl FDTD
"""
from typing import List
import numpy
def shape_source(shape: List[int] or numpy.ndarray) -> str:
"""
Defines sx, sy, sz C constants specifying the shape of the grid in each of the 3 dimensions.
:param shape: [sx, sy, sz] values.
:return: String containing C source.
"""
sxyz = """
// Field sizes
const int sx = {shape[0]};
const int sy = {shape[1]};
const int sz = {shape[2]};
""".format(shape=shape)
return sxyz
# Defines dix, diy, diz constants used for stepping in the x, y, z directions in a linear array
# (ie, given Ex[i] referring to position (x, y, z), Ex[i+diy] will refer to position (x, y+1, z))
dixyz_source = """
// Convert offset in field xyz to linear index offset
const int dix = sz * sy;
const int diy = sz;
const int diz = 1;
"""
# Given a linear index i and shape sx, sy, sz, defines x, y, and z as the 3D indices of the current element (i).
xyz_source = """
// Convert linear index to field index (xyz)
const int x = i / (sz * sy);
const int y = (i - x * sz * sy) / sz;
const int z = (i - y * sz - x * sz * sy);
"""
# Source code for updating the E field; maxes use of dixyz_source.
maxwell_E_source = """
// E update equations
Ex[i] += dt / epsx[i] * ((Hz[i] - Hz[i-diy]) - (Hy[i] - Hy[i-diz]));
Ey[i] += dt / epsy[i] * ((Hx[i] - Hx[i-diz]) - (Hz[i] - Hz[i-dix]));
Ez[i] += dt / epsz[i] * ((Hy[i] - Hy[i-dix]) - (Hx[i] - Hx[i-diy]));
"""
# Source code for updating the H field; maxes use of dixyz_source and assumes mu=0
maxwell_H_source = """
// H update equations
Hx[i] -= dt * ((Ez[i+diy] - Ez[i]) - (Ey[i+diz] - Ey[i]));
Hy[i] -= dt * ((Ex[i+diz] - Ex[i]) - (Ez[i+dix] - Ez[i]));
Hz[i] -= dt * ((Ey[i+dix] - Ey[i]) - (Ex[i+diy] - Ex[i]));
"""
def type_to_C(float_type: numpy.float32 or numpy.float64) -> str:
"""
Returns a string corresponding to the C equivalent of a numpy type.
Only works for float32 and float64.
:param float_type: numpy.float32 or numpy.float64
:return: string containing the corresponding C type (eg. 'double')
"""
if float_type == numpy.float32:
arg_type = 'float'
elif float_type == numpy.float64:
arg_type = 'double'
else:
raise Exception('Unsupported type')
return arg_type