Review at https://gerrit.osmocom.org/6825
fake_trx/data_msg.py: handle bursts properly
One L1 -> TRX message carries one to be transmitted burst encoded
as regular bits (0 or 1). One TRX -> L1 message carries one
received burst encoded as unsigned soft-bits (0..254).
This shall be noted during message encoding and decoding process.
Also, we shall distinguish between GSM and EDGE bursts.
Change-Id: I909b7a4dc70e8c632987bde07f00281a6595c4cb
---
M src/target/fake_trx/data_msg.py
1 file changed, 65 insertions(+), 13 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmocom-bb refs/changes/25/6825/1
diff --git a/src/target/fake_trx/data_msg.py b/src/target/fake_trx/data_msg.py
index c561280..2805113 100644
--- a/src/target/fake_trx/data_msg.py
+++ b/src/target/fake_trx/data_msg.py
@@ -44,6 +44,14 @@
def parse_hdr(self, hdr):
raise NotImplementedError
+ # Generates message specific burst
+ def gen_burst(self):
+ raise NotImplementedError
+
+ # Parses message specific burst
+ def parse_burst(self, burst):
+ raise NotImplementedError
+
# Generates a random frame number
def rand_fn(self):
return random.randint(0, GSM_HYPERFRAME)
@@ -159,9 +167,8 @@
hdr = self.gen_hdr()
buf += hdr
- # Put burst
- # TODO: distinguish between: usbits, ubits and sbits
- buf += bytearray(self.burst)
+ # Generate burst
+ buf += self.gen_burst()
return buf
@@ -182,7 +189,8 @@
self.parse_hdr(msg)
# Copy burst, skipping header
- self.burst = msg[self.HDR_LEN:]
+ msg_burst = msg[self.HDR_LEN:]
+ self.parse_burst(msg_burst)
class DATAMSG_L12TRX(DATAMSG):
# Constants
@@ -243,6 +251,21 @@
def parse_hdr(self, hdr):
# Parse power level
self.pwr = hdr[5]
+
+ # Generates message specific burst
+ def gen_burst(self):
+ # Copy burst 'as is'
+ return bytearray(self.burst)
+
+ # Parses message specific burst
+ def parse_burst(self, burst):
+ length = len(burst)
+
+ # Distinguish between GSM and EDGE
+ if length >= EDGE_BURST_LEN:
+ self.burst = list(burst[:EDGE_BURST_LEN])
+ else:
+ self.burst = list(burst[:GSM_BURST_LEN])
class DATAMSG_TRX2L1(DATAMSG):
# Constants
@@ -338,17 +361,46 @@
# FIXME: parsing unsupported
self.toa = None
+ # Generates message specific burst
+ def gen_burst(self):
+ # Convert soft-bits to unsigned soft-bits
+ burst_usbits = self.sbit2usbit(self.burst)
+
+ # Encode to bytes
+ return bytearray(burst_usbits)
+
+ # Parses message specific burst
+ def parse_burst(self, burst):
+ length = len(burst)
+
+ # Distinguish between GSM and EDGE
+ if length >= EDGE_BURST_LEN:
+ burst_usbits = list(burst[:EDGE_BURST_LEN])
+ else:
+ burst_usbits = list(burst[:GSM_BURST_LEN])
+
+ # Convert unsigned soft-bits to soft-bits
+ burst_sbits = self.usbit2sbit(burst_usbits)
+
+ # Save
+ self.burst = burst_sbits
+
# Regression test
if __name__ == '__main__':
# Common reference data
fn = 1024
tn = 0
- # Generate a random burst
- burst = bytearray()
+ # Generate two random bursts
+ burst_l12trx_ref = []
+ burst_trx2l1_ref = []
+
for i in range(0, GSM_BURST_LEN):
- byte = random.randint(0x00, 0xff)
- burst.append(byte)
+ ubit = random.randint(0, 1)
+ burst_l12trx_ref.append(ubit)
+
+ sbit = random.randint(-127, 127)
+ burst_trx2l1_ref.append(sbit)
print("[i] Generating the reference messages")
@@ -361,9 +413,9 @@
msg_l12trx_ref.pwr = 0x33
msg_trx2l1_ref.toa = -0.6
- # Specify the reference burst
- msg_trx2l1_ref.burst = burst
- msg_l12trx_ref.burst = burst
+ # Specify the reference bursts
+ msg_l12trx_ref.burst = burst_l12trx_ref
+ msg_trx2l1_ref.burst = burst_trx2l1_ref
print("[i] Encoding the reference messages")
@@ -382,8 +434,8 @@
print("[i] Comparing decoded messages with the reference")
# Compare bursts
- assert(msg_l12trx_dec.burst == burst)
- assert(msg_trx2l1_dec.burst == burst)
+ assert(msg_l12trx_dec.burst == burst_l12trx_ref)
+ assert(msg_trx2l1_dec.burst == burst_trx2l1_ref)
print("[?] Compare bursts: OK")
--
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I909b7a4dc70e8c632987bde07f00281a6595c4cb
Gerrit-PatchSet: 1
Gerrit-Project: osmocom-bb
Gerrit-Branch: master
Gerrit-Owner: Harald Welte <lafo...@gnumonks.org>
