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diff --git a/test/tone.py b/test/tone.py
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+#
+# Copyright (c) 2020-2021 Vasile Vilvoiu <vasi.vilvoiu@gmail.com>
+#
+# specgram is free software; you can redistribute it and/or modify
+# it under the terms of the MIT license. See LICENSE for details.
+#
+
+import argparse
+import numpy as np
+import time
+import sys
+
+def main():
+    # Argument parsing
+    parser = argparse.ArgumentParser(description='Generate a tone on stdout.')
+    parser.add_argument('freq', type=float, help='frequency of tone')
+    parser.add_argument('rate', type=float, help='sampling rate')
+    parser.add_argument('dtype', type=str, help='data type')
+    parser.add_argument('--bs', type=int, default=512, help='block size')
+    parser.add_argument('--pp', type=float, default=2.0, help='peak to peak amplitude')
+    #parser.add_argument('--rl', action='store_true', help='rate limit output')
+    args = parser.parse_args()
+
+    # Parse datatype
+    if args.dtype[0] == 'c':
+        is_complex = True
+        args.dtype = args.dtype[1:]
+    else:
+        is_complex = False
+
+    if args.dtype == 'u8':
+        dtype = np.uint8
+    elif args.dtype == 's8':
+        dtype = np.int8
+    elif args.dtype == 'u16':
+        dtype = np.uint16
+    elif args.dtype == 's16':
+        dtype = np.int16
+    elif args.dtype == 'u32':
+        dtype = np.uint32
+    elif args.dtype == 's32':
+        dtype = np.int32
+    elif args.dtype == 'u64':
+        dtype = np.uint64
+    elif args.dtype == 's64':
+        dtype = np.int64
+    elif args.dtype == 'f32':
+        dtype = np.float32
+    elif args.dtype == 'f64':
+        dtype = np.float64
+    else:
+        raise Exception('bad datatype')
+
+    index = 0
+    while True:
+        # Generate complex tone
+        t = np.linspace(index, index + args.bs - 1, args.bs, dtype=np.float128) / args.rate
+        c = np.exp(2j * np.pi * args.freq * t) / 2.0 # -0.5 .. 0.5
+
+        # Convert to output data type
+        if args.dtype[0] == 's':
+            dr = (np.real(c) * args.pp * np.iinfo(dtype).max).astype(dtype)
+            di = (np.imag(c) * args.pp * np.iinfo(dtype).max).astype(dtype)
+        elif args.dtype[0] == 'u':
+            dr = (np.real((c + 0.5) / 2.0) * args.pp * np.iinfo(dtype).max).astype(dtype)
+            di = (np.imag((c + 0.5) / 2.0) * args.pp * np.iinfo(dtype).max).astype(dtype)
+        else:
+            dr = np.real(c * args.pp).astype(dtype)
+            di = np.imag(c * args.pp).astype(dtype)
+
+        # Output block
+        if (is_complex):
+            dc = np.ravel(np.column_stack((dr, di)))
+            sys.stdout.buffer.write(dc.tobytes())
+        else:
+            sys.stdout.buffer.write(dr.tobytes())
+        sys.stdout.buffer.flush()
+
+        # Advance
+        index += args.bs
+
+if __name__ == '__main__':
+    main()