# coding: utf-8

# # Generating an OpenCL kernel by Textual Substitution

# The simplest approach to generating code is to simply substitute snippets of text into an existing code "template". This can be done using the C preprocessor, simple string-based search and replace, or other string-value interpolation functionality present in the language. The example below demonstrates the latter case:

# In[1]:

kernel = r"""
    __kernel void {name}({arguments})
    {{
      int lid = get_local_id(0);
      int gsize = get_global_size(0);
      int work_group_start = get_local_size(0)*get_group_id(0);
      long i;

      for (i = work_group_start + lid; i < n; i += gsize)
      {{
        {operation};
      }}
    }}
"""


# One slightly unfortunate fact that plays into using Python's `.format()` facility for this purpose is that opening and closing braces must be escaped by doubling them.

# In[2]:

print(kernel.format(
    name="scale",
    arguments="float *y, float a, float *x",
    operation="y[i] = a*x[i]"
))


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