3 files changed, 87 insertions, 0 deletions
diff --git a/lib/python/qmk/cli/generate/__init__.py b/lib/python/qmk/cli/generate/__init__.py
index 13bd1f0914..f9585bfb5c 100644
--- a/lib/python/qmk/cli/generate/__init__.py
+++ b/lib/python/qmk/cli/generate/__init__.py
@@ -1,2 +1,3 @@
 from . import api
 from . import docs
+from . import rgb_breathe_table
diff --git a/lib/python/qmk/cli/generate/rgb_breathe_table.py b/lib/python/qmk/cli/generate/rgb_breathe_table.py
new file mode 100644
index 0000000000..e1c5423ee5
--- /dev/null
+++ b/lib/python/qmk/cli/generate/rgb_breathe_table.py
@@ -0,0 +1,79 @@
+"""Generate rgblight_breathe_table.h
+"""
+import math
+from argparse import ArgumentTypeError
+
+from milc import cli
+
+import qmk.path
+
+
+def breathing_center(value):
+    value = float(value)
+    if value >= 1 and value <= 2.7:
+        return value
+    else:
+        raise ArgumentTypeError('Breathing center must be between 1 and 2.7')
+
+
+def breathing_max(value):
+    value = int(value)
+    if value in range(0, 256):
+        return value
+    else:
+        raise ArgumentTypeError('Breathing max must be between 0 and 255')
+
+
+@cli.argument('-c', '--center', arg_only=True, type=breathing_center, default=1.85, help='The breathing center value, from 1 to 2.7. Default: 1.85')
+@cli.argument('-m', '--max', arg_only=True, type=breathing_max, default=255, help='The breathing maximum value, from 0 to 255. Default: 255')
+@cli.argument('-o', '--output', arg_only=True, type=qmk.path.normpath, help='File to write to')
+@cli.argument('-q', '--quiet', arg_only=True, action='store_true', help='Quiet mode, only output error messages')
+@cli.subcommand('Generates an RGB Light breathing table header.')
+def generate_rgb_breathe_table(cli):
+    """Generate a rgblight_breathe_table.h file containing a breathing LUT for RGB Lighting (Underglow) feature.
+    """
+    breathe_values = [0] * 256
+    for pos in range(0, 256):
+        breathe_values[pos] = (int)((math.exp(math.sin((pos/255) * math.pi)) - cli.args.center / math.e) * (cli.args.max / (math.e - 1 / math.e)))  # noqa: yapf insists there be no whitespace around /
+
+    values_template = ''
+    for s in range(0, 3):
+        step = 1 << s
+
+        values_template += '#if RGBLIGHT_BREATHE_TABLE_SIZE == {}\n'.format(256 >> s)
+
+        for pos in range(0, 256, step):
+            values_template += '    ' if pos % 8 == 0 else ''
+            values_template += '0x{:02X}'.format(breathe_values[pos])
+            values_template += ',' if (pos + step) < 256 else ''
+            values_template += '\n' if (pos+step) % 8 == 0 else ' '  # noqa: yapf insists there be no whitespace around +
+
+        values_template += '#endif'
+        values_template += '\n\n' if s < 2 else ''
+
+    table_template = '''#pragma once
+
+#define RGBLIGHT_EFFECT_BREATHE_TABLE
+
+// clang-format off
+
+// Breathing center: {0:.2f}
+// Breathing max:    {1:d}
+
+const uint8_t PROGMEM rgblight_effect_breathe_table[] = {{
+{2}
+}};
+
+static const int table_scale = 256 / sizeof(rgblight_effect_breathe_table);
+'''.format(cli.args.center, cli.args.max, values_template)
+
+    if cli.args.output:
+        cli.args.output.parent.mkdir(parents=True, exist_ok=True)
+        if cli.args.output.exists():
+            cli.args.output.replace(cli.args.output.name + '.bak')
+        cli.args.output.write_text(table_template)
+
+        if not cli.args.quiet:
+            cli.log.info('Wrote header to %s.', cli.args.output)
+    else:
+        print(table_template)
diff --git a/lib/python/qmk/tests/test_cli_commands.py b/lib/python/qmk/tests/test_cli_commands.py
index dd0c572a7d..ee8b1144c1 100644
--- a/lib/python/qmk/tests/test_cli_commands.py
+++ b/lib/python/qmk/tests/test_cli_commands.py
@@ -190,3 +190,10 @@ def test_clean():
     result = check_subcommand('clean', '-a')
     check_returncode(result)
     assert result.stdout.count('done') == 2
+
+
+def test_generate_rgb_breathe_table():
+    result = check_subcommand("generate-rgb-breathe-table", "-c", "1.2", "-m", "127")
+    check_returncode(result)
+    assert 'Breathing center: 1.2' in result.stdout
+    assert 'Breathing max:    127' in result.stdout