mirror of
https://github.com/ratspeak/C6-Reticulum-ASM
synced 2026-08-12 18:07:18 -04:00
27e75f5281
Polled NS16550A receive primitives. uart_rx_byte spins on LSR.DR (bit 0) until a byte arrives, then reads RBR. uart_rx_available returns 1/0 of the same DR bit, non-blocking. Both stay as the polled fall-back even after uart_isr lands; the IRQ-driven ring-buffer path will become the production hot path on the C6, the polled forms keep working on qemu-virt where qemu does not model the PLIC for our IRQ wiring.
33 lines
1.1 KiB
Python
33 lines
1.1 KiB
Python
"""Tests for src/uart/uart_rx_available.S — non-blocking RX-ready check."""
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from __future__ import annotations
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import re
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import pytest
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from harness import build
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@pytest.fixture(scope="module")
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def artifacts() -> build.BuildArtifacts:
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return build.build("qemu-virt")
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def test_function_exists(artifacts: build.BuildArtifacts) -> None:
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assert build.symbol_address(artifacts.elf, "uart_rx_available") > 0
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def test_returns_dr_bit(artifacts: build.BuildArtifacts) -> None:
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body = build.objdump_disassemble(artifacts.elf, symbol="uart_rx_available")
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# `lbu t1, 5(t0)` then `andi a0, t1, 1` — the DR bit becomes a0.
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assert re.search(r"\blbu\b\s+t1,\s*5\(t0\)", body), body
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assert re.search(r"\bandi\b\s+a0,\s*t1,\s*1\b", body), body
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def test_no_branches(artifacts: build.BuildArtifacts) -> None:
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"""Non-blocking — no loop, no branches."""
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body = build.objdump_disassemble(artifacts.elf, symbol="uart_rx_available")
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for line in body.splitlines():
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assert not re.search(r"\b(beq|bne|blt|bge|bltu|bgeu|beqz|bnez|j|jal)\s", line) \
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or "ret" in line or "jalr" in line, line
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