Refactor lidar library: rename olei_config to lidar_config, add nanoscan example and shared byte helpers

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/lidar_bytes.hpp

@@ -0,0 +1,42 @@
+// Internal helpers shared by the driver TUs — not part of the public API.
+#pragma once
+#include "lidarlib/lidar.hpp"
+#include <cstdint>
+#include <cstring>
+
+namespace lidarlib {
+
+inline constexpr float kDeg2Rad = 3.14159265358979323846f / 180.f;
+
+// Remap a finished scan's angular window onto [min_deg, max_deg]. Only
+// angle_min/angle_max/angle_increment are rewritten; points are untouched.
+inline void remap_scan_window(LaserScan& scan, float min_deg, float max_deg) {
+    const float new_min  = min_deg * kDeg2Rad;
+    const float new_max  = max_deg * kDeg2Rad;
+    const float old_span = scan.angle_max - scan.angle_min;
+    if (old_span > 0.f)
+        scan.angle_increment *= (new_max - new_min) / old_span;
+    scan.angle_min = new_min;
+    scan.angle_max = new_max;
+}
+
+// Little-endian readers (bounds are the caller's responsibility).
+inline uint8_t  le_u8 (const uint8_t* p) { return p[0]; }
+inline uint16_t le16(const uint8_t* p) {
+    return static_cast<uint16_t>(p[0] | (p[1] << 8));
+}
+inline uint32_t le32(const uint8_t* p) {
+    return static_cast<uint32_t>(p[0])
+         | (static_cast<uint32_t>(p[1]) <<  8)
+         | (static_cast<uint32_t>(p[2]) << 16)
+         | (static_cast<uint32_t>(p[3]) << 24);
+}
+inline int32_t  le_i32(const uint8_t* p) { return static_cast<int32_t>(le32(p)); }
+
+inline float bits_to_float(uint32_t bits) {
+    float f;
+    std::memcpy(&f, &bits, sizeof(f));
+    return f;
+}
+
+} // namespace lidarlib