MAINT: Convert backlash to C++.

Author: WarrenWeckesser

pyproject.toml

@@ -8,7 +8,7 @@ requires = [
 
 [project]
 name = 'ufunclab'
-version = '0.0.8.dev10'
+version = '0.0.8.dev11'
 description = 'NumPy ufuncs and utilities.'
 readme = 'README.md'
 requires-python = '>=3.9'

src/backlash/backlash_gufunc.c.src

@@ -0,0 +1,45 @@
+#ifndef BACKLASH_GUFUNC_H
+#define BACKLASH_GUFUNC_H
+
+#define PY_SSIZE_T_CLEAN
+#include "Python.h"
+
+#define NPY_NO_DEPRECATED_API NPY_API_VERSION
+#include "numpy/ndarraytypes.h"
+
+#include "../src/util/strided.hpp"
+
+
+template<typename T>
+static void
+backlash_core(
+        npy_intp n,                     // core dimension n
+        T *p_x,                         // pointer to first element of x, a strided 1-d array with shape (n,)
+        const npy_intp x_stride,        // stride (in bytes) of x
+        T *p_deadband,                  // pointer to deadband
+        T *p_initial,                   // pointer to initial
+        T *p_out,                       // pointer to out, a strided 1-d array with shape (n,)
+        const npy_intp out_stride       // stride (in bytes) of out
+)
+{
+    T deadband = *p_deadband;
+    T initial = *p_initial;
+    T halfband = deadband/2;
+    T current_y = initial;
+    for (npy_intp k = 0; k < n; ++k) {
+        T current_x = get(p_x, x_stride, k);
+        T xminus = current_x - halfband;
+        if (xminus > current_y) {
+            current_y = xminus;
+        }
+        else {
+            T xplus = current_x + halfband;
+            if (xplus < current_y) {
+                current_y = xplus;
+            }
+        }
+        set(p_out, out_stride, k, current_y);
+    }
+}
+
+#endif

src/backlash/backlash_gufunc.h

@@ -0,0 +1,55 @@
+
+
+from ufunc_config_types import UFuncExtMod, UFunc, UFuncSource
+
+
+BACKLASH_DOCSTRING = """\
+backlash(x, deadband, initial, /, ...)
+
+Compute the backlash signal of the input signal x.
+
+Parameters
+----------
+x : array_like
+    Input signal
+deadband : scalar
+    Width of the deadband of the backlash process.
+initial : scalar
+    Initial state of the output.
+
+Returns
+-------
+out : ndarray
+    Output of the backlash process.
+
+Examples
+--------
+>>> x = np.array([0, 1, 1.1, 1.0, 1.5, 1.4, 1.2, 0.5])
+>>> backlash(x, 0.4, 0.0)
+array([0. , 0.8, 0.9, 0.9, 1.3, 1.3, 1.3, 0.7])
+"""
+
+
+backlash_core_source = UFuncSource(
+    funcname='backlash_core',
+    typesignatures=['fff->f', 'ddd->d', 'ggg->g'],
+)
+
+backlash_gufunc = UFunc(
+    name='backlash',
+    docstring=BACKLASH_DOCSTRING,
+    header='backlash_gufunc.h',
+    signature='(n),(),() -> (n)',
+    sources=[backlash_core_source],
+)
+
+
+MODULE_DOCSTRING = """\
+This module defines the backlash function.
+"""
+
+extmod = UFuncExtMod(
+    module='_backlash',
+    docstring=MODULE_DOCSTRING,
+    ufuncs=[backlash_gufunc],
+)

src/backlash/define_cxx_gufunc_extmod.py

@@ -47,6 +47,7 @@ npymath_lib = cc.find_library('npymath', dirs: npymath_path)
 
 gufunc_cxx_src_dirs = [
     'all_same',
+    'backlash',
     'corr',
     'mad',
     'meanvar',
@@ -188,7 +189,6 @@ py3.extension_module(
 #----------------------------------------------------------------------
 
 numpy_templated_c_gufunc_dirs = [
-    'backlash',
     'cross',
     'fillnan1d',
     'first',
@@ -201,11 +201,11 @@ numpy_templated_c_gufunc_dirs = [
 
 foreach src_dir : numpy_templated_c_gufunc_dirs
 
-    module_name = '_' + src_dir                       # e.g. '_backlash'
-    output = src_dir + '_gufunc.c'                    # e.g. 'backlash_gufunc.c'
-    src_filename = output + '.src'                    # e.g. 'backlash_gufunc.c.src'
-    src_pth = join_paths('../src', src_dir)           # e.g. '../src/backlash'
-    src_fullpath = join_paths(src_pth, src_filename)  # e.g. '../src/blacklash/backlash_gufunc.c.src'
+    module_name = '_' + src_dir                       # e.g. '_fillnan1d'
+    output = src_dir + '_gufunc.c'                    # e.g. 'fillnan1d_gufunc.c'
+    src_filename = output + '.src'                    # e.g. 'fillnan1d_gufunc.c.src'
+    src_pth = join_paths('../src', src_dir)           # e.g. '../src/fillnan1d'
+    src_fullpath = join_paths(src_pth, src_filename)  # e.g. '../src/fillnan1d/fillnan1d_gufunc.c.src'
 
     mod_src = custom_target(
                   src_dir,