From df2183ce5488a7dc8d42e34dd6f2609a1ac3b5d2 Mon Sep 17 00:00:00 2001
From: Luciano Righetti <luciano.righetti@gmail.com>
Date: Thu, 13 Jul 2023 11:06:25 +0200
Subject: [PATCH] fix: properly read samples in different datatypes

---
 .../modules/expansion/sigmf-expand.py         | 74 ++++++++++---------
 1 file changed, 41 insertions(+), 33 deletions(-)

diff --git a/misp_modules/modules/expansion/sigmf-expand.py b/misp_modules/modules/expansion/sigmf-expand.py
index def1e1b..ec51106 100644
--- a/misp_modules/modules/expansion/sigmf-expand.py
+++ b/misp_modules/modules/expansion/sigmf-expand.py
@@ -30,52 +30,60 @@ moduleinfo = {'version': '0.1', 'author': 'Luciano Righetti',
               'module-type': ['expansion']}
 
 
-def generate_plots(recording, meta_filename):
+def get_samples(data_bytes, data_type) -> np.ndarray:
+    """
+    Get samples from bytes.
+
+    Source: https://github.com/IQEngine/IQEngine/blob/main/api/rf/samples.py
+
+    Parameters
+    ----------
+    data_bytes : bytes
+        The bytes to convert to samples.
+    data_type : str
+        The data type of the bytes.
+
+    Returns
+    -------
+    np.ndarray
+        The samples.
+    """
+
+    if data_type == "ci16_le" or data_type == "ci16":
+        samples = np.frombuffer(data_bytes, dtype=np.int16)
+        samples = samples[::2] + 1j * samples[1::2]
+    elif data_type == "cf32_le":
+        samples = np.frombuffer(data_bytes, dtype=np.complex64)
+    elif data_type == "ci8" or data_type == "i8":
+        samples = np.frombuffer(data_bytes, dtype=np.int8)
+        samples = samples[::2] + 1j * samples[1::2]
+    else:
+        raise ("Datatype " + data_type + " not implemented")
+    return samples
+
+
+def generate_plots(recording, meta_filename, data_bytes):
     # FFT plot
     filename = meta_filename.replace('.sigmf-data', '')
-    # snippet from https://gist.github.com/daniestevez/0d519fd4044f3b9f44e170fd619fbb40
-    NFFT = 2048
-    N = NFFT * 4096
-    fs = recording.get_global_info()['core:sample_rate']
-    x = np.fromfile(recording.data_file, 'int16', count=2*N)
-    x = x[::2] + 1j * x[1::2]
-
-    # f = np.fft.fftshift(np.average(
-    #     np.abs(np.fft.fft(x.reshape(-1, NFFT)))**2, axis=0))
-    # freq = np.fft.fftshift(np.fft.fftfreq(NFFT, 1/fs))
-
-    # plt.figure(figsize=(10, 4))
-    # plt.plot(1e-6 * freq, 10*np.log10(f))
-    # plt.title(filename)
-    # plt.ylabel('PSD (dB)')
-    # plt.xlabel('Baseband frequency (MHz)')
-    # fft_buff = io.BytesIO()
-    # plt.savefig(fft_buff, format='png')
-    # fft_buff.seek(0)
-    # fft_png = base64.b64encode(fft_buff.read()).decode('utf-8')
-
-    # fft_attr = {
-    #     'type': 'attachment',
-    #     'value': filename + '-fft.png',
-    #     'data': fft_png,
-    #     'comment': 'FFT plot of the recording'
-    # }
+    samples = get_samples(
+        data_bytes, recording.get_global_info()['core:datatype'])
+    sample_rate = recording.get_global_info()['core:sample_rate']
 
     # Waterfall plot
     # snippet from https://pysdr.org/content/frequency_domain.html#fast-fourier-transform-fft
     fft_size = 1024
     # // is an integer division which rounds down
-    num_rows = len(x) // fft_size
+    num_rows = len(samples) // fft_size
     spectrogram = np.zeros((num_rows, fft_size))
     for i in range(num_rows):
         spectrogram[i, :] = 10 * \
             np.log10(np.abs(np.fft.fftshift(
-                np.fft.fft(x[i*fft_size:(i+1)*fft_size])))**2)
+                np.fft.fft(samples[i*fft_size:(i+1)*fft_size])))**2)
 
     plt.figure(figsize=(10, 4))
     plt.title(filename)
     plt.imshow(spectrogram, aspect='auto', extent=[
-               fs/-2/1e6, fs/2/1e6, 0, len(x)/fs])
+               sample_rate/-2/1e6, sample_rate/2/1e6, 0, len(samples)/sample_rate])
     plt.xlabel("Frequency [MHz]")
     plt.ylabel("Time [ms]")
     plt.savefig(filename + '-spectrogram.png')
@@ -91,7 +99,6 @@ def generate_plots(recording, meta_filename):
         'comment': 'Waterfall plot of the recording'
     }
 
-    # return [fft_attr, waterfall_attr]
     return [{'relation': 'waterfall-plot', 'attribute': waterfall_attr}]
 
 
@@ -176,7 +183,8 @@ def handler(q=False):
 
     # add FFT and waterfall plot
     try:
-        plots = generate_plots(recording, sigmf_data_attr['value'])
+        plots = generate_plots(
+            recording, sigmf_data_attr['value'], sigmf_data_bin)
     except Exception as e:
         logging.exception(e)
         return {"error": "Could not generate plots"}