0966fa8cfc
The firmware has never been flashed, and a real bug already reached the repo because of it: RD03E_FRAME_LEN was 5 for a 6-byte frame, so the footer check collided with the distance high byte and EVERY distance reading was garbage — always `lo | 0x5500`, about 218 metres, regardless of what the sensor saw. That was pure logic with no hardware dependency. It should have been catchable on a laptop, and there was simply no way to run the code. Extracted the hardware-free logic out of the three drivers — rd03e_parse, bmp280_compensate, mems_level — as moves rather than rewrites, carrying the explanatory comments along with the code they explain. The drivers now own only their bus I/O and call into the pure units, so nothing changes for the real device. `./run_tests.sh` builds them with gcc -Wall -Wextra -Werror plus a dependency-free assert harness: 175 checks, 0 failed, from a clean tree. Proven to catch the actual bug rather than assumed to: reintroducing FRAME_LEN 5 fails four checks, including one that reads "a simple-report frame is 6 bytes, not 5", plus the truncated-frame and 5-byte-window cases. Restored, green again. This does NOT make the firmware verified, and the README says so plainly — it is called a narrow exception and scoped to pure logic. Wiring, timing, real register behaviour and the reconstructed RD-03E frame format all still need the physical board. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
44 lines
1.7 KiB
C
44 lines
1.7 KiB
C
// RD-03E frame scanner — pure logic, host-testable. See rd03e_parse.h.
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#include "rd03e_parse.h"
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bool rd03e_parse_latest(const uint8_t *buf, size_t len, rd03e_frame_t *out) {
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if (buf == NULL || out == NULL || len < RD03E_FRAME_LEN) {
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return false;
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}
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bool parsed_any = false;
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rd03e_frame_t latest = {0};
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// Scan for the newest complete, validated frame in whatever arrived
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// this cycle; keep overwriting `latest` so we report the freshest one.
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//
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// The `i + RD03E_FRAME_LEN <= len` bound is what makes a truncated
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// trailing frame get ignored rather than read past the buffer: a
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// partial frame at the end simply never satisfies the bound.
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for (size_t i = 0; i + RD03E_FRAME_LEN <= len; i++) {
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if (buf[i] != RD03E_FRAME_HEADER) {
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continue;
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}
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// Footer lives at [4] and [5] of the frame. If this offset only
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// *looks* like a header (a 0xAA that is really a distance byte, a
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// gesture code, or line noise), the footer check rejects it and
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// the scan resynchronises on the next byte.
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if (buf[i + 4] != RD03E_FRAME_FOOTER0 || buf[i + 5] != RD03E_FRAME_FOOTER1) {
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continue; // not a real header byte, or a corrupted frame
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}
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latest.gesture = buf[i + 1];
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// Little-endian: low byte first. Getting this backwards, or
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// letting the footer bytes bleed into the high byte, is exactly
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// the bug this unit exists to make testable.
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latest.distance_cm = (uint16_t)((uint16_t)buf[i + 2] | ((uint16_t)buf[i + 3] << 8));
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parsed_any = true;
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i += RD03E_FRAME_LEN - 1; // loop's i++ moves past this frame
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}
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if (parsed_any) {
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*out = latest;
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}
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return parsed_any;
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}
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