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.
35 lines
1.1 KiB
Python
35 lines
1.1 KiB
Python
"""Tests for src/uart/uart_rx_byte.S — polled NS16550A read."""
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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_byte") > 0
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def test_loads_uart0_base(artifacts: build.BuildArtifacts) -> None:
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body = build.objdump_disassemble(artifacts.elf, symbol="uart_rx_byte")
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assert re.search(r"\blui\b\s+t0,\s*0x10000\b", body), body
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def test_polls_dr_bit(artifacts: build.BuildArtifacts) -> None:
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body = build.objdump_disassemble(artifacts.elf, symbol="uart_rx_byte")
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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+t1,\s*t1,\s*1\b", body), body
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assert re.search(r"\bbeqz\b\s+t1", body), body
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def test_reads_from_rbr_into_a0(artifacts: build.BuildArtifacts) -> None:
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body = build.objdump_disassemble(artifacts.elf, symbol="uart_rx_byte")
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assert re.search(r"\blbu\b\s+a0,\s*0\(t0\)", body), body
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