user
47 lines
1.8 KiB
Markdown
47 lines
1.8 KiB
Markdown
# K10 — Queue<T> and StaticQueue<T, N>
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## Position
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- Series: FreeRTOS C++
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- Lesson: L09, card K10
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- Duration: 30 minutes
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- Platform: Hazard3 / RV32I, FreeRTOS V11.3.0
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- Message: 12-byte trivial `Sample`, capacity 2
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## Outcome
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The student explains byte-copy semantics, designs a trivial message, proves a
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copy survives source mutation, compares dynamic and caller-owned static queue
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storage, and handles full/empty states with explicit bounded timeouts.
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## Lesson plan
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| Time | Mode | Evidence |
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| --- | --- | --- |
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| 0–5 | type contract | `Sample` passes; owning `VectorV1` fails |
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| 5–10 | create | dynamic cost 128 B; static delta 0 B |
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| 10–15 | copy | send, mutate source, receive unchanged copy |
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| 15–20 | storage | inspect first 12 static storage bytes |
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| 20–25 | full/timeout | capacity 2; third send fails after 2 ticks |
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| 25–30 | FIFO/drain | values 0x2222 then 0x3333; empty receive fails |
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## Acceptance
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- `sizeof(Sample)==12` reaches both create APIs;
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- dynamic cost is positive and recovered by RAII destruction;
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- static create has zero heap delta and its buffers are in `.bss`;
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- received value remains 0x1111 after source becomes 0xDEAD;
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- storage snapshot equals the first sent `Sample` byte-for-byte;
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- full count is 2, third send returns false after at least 2 ticks;
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- FIFO and non-blocking empty receive are correct;
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- non-trivial owning message fails for the pinned static-assert reason;
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- target exits with PASS.
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## Main traps
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1. Queue storage is a byte copy, not a C++ object owner.
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2. `sizeof(pointer)` plus an object address is a different and invalid contract.
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3. A trivially-copyable pointer still needs an external lifetime policy.
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4. `portMAX_DELAY` must not be hidden as a convenient default.
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5. Static queue control and byte storage must both outlive the queue.
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