def _init_double_scan(self):
""""generates a double scan on indexes and values in one operation"""
arguments = "__global int *value", "__global int *index"
int2 = pyopencl.tools.get_or_register_dtype("int2")
input_expr = "index[i]>0 ? (int2)(0, 0) : (int2)(value[i], 1)"
scan_expr = "a+b"
neutral = "(int2)(0,0)"
output_statement = "value[i] = item.s0; index[i+1] = item.s1;"
if self.block_size > 256:
knl = GenericScanKernel(self.ctx,
dtype=int2,
arguments=arguments,
input_expr=input_expr,
scan_expr=scan_expr,
neutral=neutral,
output_statement=output_statement)
else: # MacOS on CPU
knl = GenericDebugScanKernel(self.ctx,
dtype=int2,
arguments=arguments,
input_expr=input_expr,
scan_expr=scan_expr,
neutral=neutral,
output_statement=output_statement)
return knl
def _init_compression_scan(self):
"""Initialize CBF compression scan kernels"""
preamble = """
int compressed_size(int diff) {
int abs_diff = abs(diff);
if (abs_diff < 128) {
return 1;
}
else if (abs_diff < 32768) {
return 3;
}
else {
return 7;
}
}
void write(const int index,
const int diff,
global char *output) {
int abs_diff = abs(diff);
if (abs_diff < 128) {
output[index] = (char) diff;
}
else if (abs_diff < 32768) {
output[index] = -128;
output[index + 1] = (char) (diff >> 0);
output[index + 2] = (char) (diff >> 8);
}
else {
output[index] = -128;
output[index + 1] = 0;
output[index + 2] = -128;
output[index + 3] = (char) (diff >> 0);
output[index + 4] = (char) (diff >> 8);
output[index + 5] = (char) (diff >> 16);
output[index + 6] = (char) (diff >> 24);
}
}
"""
arguments = "__global const int *data, __global char *compressed, __global int *size"
input_expr = "compressed_size((i == 0) ? data[0] : (data[i] - data[i - 1]))"
scan_expr = "a+b"
neutral = "0"
output_statement = """
if (prev_item == 0) { // 1st thread store compressed data size
size[0] = last_item;
}
write(prev_item, (i == 0) ? data[0] : (data[i] - data[i - 1]), compressed);
"""
if self.block_size >= 64:
knl = GenericScanKernel(self.ctx,
dtype=numpy.int32,
preamble=preamble,
arguments=arguments,
input_expr=input_expr,
scan_expr=scan_expr,
neutral=neutral,
output_statement=output_statement)
else: # MacOS on CPU
knl = GenericDebugScanKernel(self.ctx,
dtype=numpy.int32,
preamble=preamble,
arguments=arguments,
input_expr=input_expr,
scan_expr=scan_expr,
neutral=neutral,
output_statement=output_statement)
return knl