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feat(cobs): Fixed issue when exactly 255 bytes (non zero) are encoded. #780

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Merged
finger563 merged 2 commits into from
Sep 7, 2026
+19 −2
Merged

feat(cobs): Fixed issue when exactly 255 bytes (non zero) are encoded. #780

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7eb81ae
Fixed issue when exactly 255 bytes (non zero) are encoded.
jschuld Sep 7, 2026
bf0c025
copilot code review feedback.
jschuld Sep 7, 2026
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18 changes: 18 additions & 0 deletions components/cobs/example/main/cobs_example.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -682,6 +682,24 @@ void test_edge_cases(espp::Logger &logger) {
decoded.size(), large_packet.size(), encoded.size());
}
}

// Test 5: Packet of exactly 255 bytes with no zeros in the data
{
std::vector<uint8_t> block_len_packet(255, 0x42);

std::vector<uint8_t> encoded = Cobs::encode_packet(block_len_packet);
std::vector<uint8_t> decoded = Cobs::decode_packet(encoded);

bool success = (decoded.size() == block_len_packet.size()) &&
(std::memcmp(decoded.data(), block_len_packet.data(), block_len_packet.size()) == 0);
if (success) {
logger.info("Test 5: PASS - Packet of exactly 255 bytes with no zeros");
} else {
logger.error(
"Test 5: FAIL - Packet of exactly 255 bytes with no zeros (decoded: {}, expected: {}, encoded: {})",
decoded.size(), block_len_packet.size(), encoded.size());
}
}
}

extern "C" void app_main(void) {
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3 changes: 1 addition & 2 deletions components/cobs/src/cobs.cpp
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Expand Up @@ -44,8 +44,7 @@ size_t Cobs::encode_packet(std::span<const uint8_t> data, std::span<uint8_t> out
*codep = code;
code = 1;
codep = encode;
if (!byte)
++encode;
++encode;

@jschuld jschuld Sep 7, 2026

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If the loop ends because of no more data, we still want to ready the next encoding position for the delimiter to be added.

}
}
*codep = code; // Write final code value
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