From 8f4b7e1fa168aabfd0e3c35cdef04b2ae40df0c9 Mon Sep 17 00:00:00 2001
From: Andreas Tsouchlos <an.tsouchlos@gmail.com>
Date: Mon, 14 Nov 2022 11:12:46 +0100
Subject: [PATCH] Added rough implementation of Simulator class

---
 sw/utility/simulation.py | 139 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)

diff --git a/sw/utility/simulation.py b/sw/utility/simulation.py
index 24cd8fb..26798e8 100644
--- a/sw/utility/simulation.py
+++ b/sw/utility/simulation.py
@@ -122,6 +122,145 @@ def count_bit_errors(d: np.array, d_hat: np.array) -> int:
 #     return SNRs, result_BERs
 #
 
+
+class Simulator:
+    def __init__(self, n: int, k: int,
+                 decoders: typing.Sequence[typing.Any],
+                 SNRs: typing.Sequence[float],
+                 target_frame_errors: int):
+        """Construct and object of type simulator.
+
+        TODO: ...
+
+        :param n:
+        :param k:
+        :param decoders:
+        :param SNRs:
+        :param target_frame_errors:
+        """
+        # Simulation parameters
+
+        self._n = n
+        self._k = k
+        self._decoders = decoders
+        self._SNRs = SNRs
+        self._target_frame_errors = target_frame_errors
+
+        self._x = np.zeros(self._n)
+        self._x_bpsk = 1 - 2 * self._x  # Map x from [0, 1]^n to [-1, 1]^n
+
+        # Simulation state
+
+        self._current_decoder_index = 0
+        self._current_SNRs_index = 0
+
+        self._curr_num_frame_errors = 0
+        self._curr_num_bit_errors = 0
+        self._curr_num_total_bits = 0
+
+        # Results
+
+        self._BERs = []
+
+    def _update_sim_state(self, bit_errors: int):
+        pass
+
+    def _simulate_transmission(self, decoder: typing.Any, SNR: float) -> bool:
+        # Simulate channel
+        y = noise.add_awgn(self._x_bpsk, SNR, self._n, self._k)
+
+        # Decode received frame
+        x_hat = decoder.decode(y)
+
+        # Update statistics
+        bit_errors = count_bit_errors(self._x, x_hat)
+        self._curr_num_total_bits += self._x.size
+
+        if bit_errors > 0:
+            self._curr_num_frame_errors += 1
+            self._curr_num_total_bits += bit_errors
+
+        return bit_errors > 0
+
+    def _simulate_SNR(self, SNR):
+        pbar = tqdm(total=self._target_frame_errors,
+                    desc=f"Simulating for SNR = {SNR} dB", position=2, leave=False,
+                    bar_format="{l_bar}{bar}| {n_fmt}/{total_fmt} [{elapsed}<{remaining}]")
+
+        while self._curr_num_frame_errors < self._target_frame_errors:
+            error_occurred = self._simulate_transmission()
+            if error_occurred:
+                pbar.update(1)
+        pbar.close()
+
+        self._BERs.append(self._curr_num_bit_errors / self._curr_num_total_bits)
+
+    def
+
+    def test_decoder(self) -> typing.Tuple[np.array, np.array]:
+        """Calculate the Bit Error Rate (BER) for a given decoder for a number of SNRs.
+
+        This function assumes the all-zeros assumption holds. Progress is printed to stdout.
+
+        :return: Tuple of numpy arrays of the form (SNRs, BERs)
+        """
+
+        decoder = self._decoders[self._current_decoder_index]
+
+        for SNR in tqdm(self._SNRs[self._current_SNRs_index:],
+                        desc=f"Calculating BERs for {decoder.__class__.__name__}",
+                        position=1, leave=False, bar_format="{l_bar}{bar}| {n_fmt}/{total_fmt}"):
+
+            pbar = tqdm(total=self._target_frame_errors,
+                        desc=f"Simulating for SNR = {SNR} dB", position=2, leave=False,
+                        bar_format="{l_bar}{bar}| {n_fmt}/{total_fmt} [{elapsed}<{remaining}]")
+
+            while self._curr_num_frame_errors < self._target_frame_errors:
+                error_occurred = self._simulate_transmission()
+                if error_occurred:
+                    pbar.update(1)
+            pbar.close()
+
+            self._BERs.append(self._curr_num_bit_errors / self._curr_num_total_bits)
+
+        return np.array(self._SNRs), np.array(self._BERs)
+
+
+    def test_decoders(n: int,
+                      k: int,
+                      decoders: typing.List,
+                      SNRs: typing.Sequence[float] = np.linspace(1, 7, 7),
+                      target_frame_errors: int = 100) \
+            -> typing.Tuple[np.array, np.array]:
+        """Calculate the Bit Error Rate (BER) for a number of given decoders for a number of SNRs.
+
+        This function assumes the all-zeros assumption holds. Progress is printed to stdout.
+
+        :param n: Length of a codeword of the used code
+        :param k: Length of a dataword of the used code
+        :param decoders: List of decoder objects to be tested
+        :param SNRs: List of SNRs for which the BER should be calculated
+        :param target_frame_errors: Number of frame errors after which to stop the simulation
+        :return: Tuple of the form (SNRs, [BERs_1, BERs_2, ...]) where SNR and BERs_x are numpy arrays
+        """
+        result_BERs = []
+
+        start_time = default_timer()
+
+        for decoder in tqdm(decoders,
+                            desc="Calculating the answer to life, the universe and everything",
+                            position=0,
+                            leave=False,
+                            bar_format="{l_bar}{bar}| {n_fmt}/{total_fmt}"):
+            _, BERs = test_decoder(n, k, decoder, SNRs, target_frame_errors)
+            result_BERs.append(BERs)
+
+        end_time = default_timer()
+        print(f"Elapsed time: {end_time - start_time:.2f}s")
+
+        return SNRs, result_BERs
+
+
 @dataclass
 class SimulationParameters:
     n: int