persist_array_file.tc

persist_array_file.tc — script-managed persistence for arrays that

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// persist_array_file.tc — script-managed persistence for arrays that
// must NOT be lost.
//
// WHY (vs `persist` / .pvs):
//   The .pvs auto-persist seals the file with a layout hash. Any
//   add/remove/resize of a `persist` variable invalidates it and (pre
//   1.6.10) wiped ALL values; even with the 1.6.10 .pvs.bak net it is
//   the firmware that decides to discard. For large/critical tables
//   (config, tariff/SOC schedules, meter totals, chart history) own
//   the file in the script: a leading FORMAT version + explicit,
//   field-wise migration. Immune to firmware flashes and layout
//   changes — the script, not the firmware, decides what happens.
//
// Uses the BINARY array I/O builtins (fileWriteBin/fileReadBin):
// raw 4-byte little-endian int32 — compact, exact, no text rounding.
// Works for int[] AND float[] (both are int32 in memory, so float
// bit-patterns survive verbatim — right for chart/sensor history).
// Cost is tiny; only the migrate branch is hand-written, and only
// runs when YOU bump FORMAT.

#define DATAFILE "/appcfg.bin"
#define FORMAT   2                 // bump when the layout changes

// ---- the data to protect (sizes are yours) ------------------------
int   cfg[8];                      // device config
float tariff[12];                  // 12 tariff zones (floats: exact)
int   hdr[1];                      // record 0: [FORMAT]

// ---- save: header record + each array, fixed counts ---------------
void saveData() {
  int h = fileOpen(DATAFILE, 1);   // 1 = write (truncates)
  if (h < 0) { return; }
  hdr[0] = FORMAT;
  fileWriteBin(h, hdr,    1);
  fileWriteBin(h, cfg,    8);
  fileWriteBin(h, tariff, 12);
  fileClose(h);
}

// ---- defaults: only for a missing/unreadable file -----------------
void setDefaults() {
  int i = 0;
  while (i < 8)  { cfg[i]    = 0;   i = i + 1; }
  i = 0;
  while (i < 12) { tariff[i] = 0.0; i = i + 1; }
}

// ---- load: version-gated, explicit migration ----------------------
void loadData() {
  int h = fileOpen(DATAFILE, 0);   // 0 = read
  if (h < 0) { setDefaults(); return; }     // first run / no file

  setDefaults();                            // baseline for any gaps
  int n = fileReadBin(h, hdr, 1);           // record 0
  int ver = -1;
  if (n == 1) { ver = hdr[0]; }

  if (ver == FORMAT) {
    fileReadBin(h, cfg,    8);              // current layout
    fileReadBin(h, tariff, 12);
  } else if (ver == 1) {
    // --- migration v1 -> v2 ---
    // v1 had cfg[6] only and no tariff[]. Read what exists; defaults
    // (set above) cover the rest. Re-save in the new format so the
    // next boot is on FORMAT 2.
    fileReadBin(h, cfg, 6);
    fileClose(h);
    saveData();
    return;
  }
  // unknown/corrupt: keep file for recovery, run on defaults (no-op).
  fileClose(h);
}

void main() {
  loadData();
  // ... use cfg[]/tariff[] ...
}

// Persist on shutdown/reload, and call saveData() yourself whenever a
// value changes — there is no flash-wear-free auto-save here, that is
// the point: you control exactly when it is written.
void OnExit() {
  saveData();
}