Files
essim/doc/user/analysis.md
François 7d307dad57 Export command (CSV + ODS), file dialog, error modal, path persistence.
New user-facing features:
- `export connections <file>` writes a tabular dump of every wire pair:
  connection, transform, left/right module/part/pin/signal/type/suspect,
  mixed-types flag. Dispatch on extension: `.csv` (flat file) or `.ods`
  (one sheet per connection). Any other extension shows an error and
  writes nothing.
- Bare `export` (or dashboard `[x]`, or palette `export`) opens an
  interactive file-picker dialog with a CSV/ODS toggle at the top.
  Picking a filter rewrites the filename's extension. Last-used
  directory and filename are remembered per-call-site.
- Two new CLI flags on the binary: `--source FILE` to run a script at
  boot, `--restore FILE` to restore a snapshot at boot. Combinable.

Reusable infrastructure:
- `OdsWriter` (`src/imports/ods_writer.{hpp,cpp}`): minimal .ods writer
  using libzip + pugixml (already in the build for the importer).
  Multi-sheet workbook of string cells. ~180 lines, no new dep.
- Generic file-picker dialog (`screen_filedialog.cpp`): one Modal
  reused for any "pick a path" interaction via
  `OpenFileDialog(title, persist_key, default_filename, filters, cb)`.
  Validates the picked extension against the filter whitelist;
  unknown ones stay in the dialog with a status message. Persists
  (dir, filename) per `persist_key`.
- Generic error modal (`screen_error.cpp`, `ShowError(msg)`): centred
  red-titled popup, dismissable with Esc/Enter. Used by the export
  failures (open-for-write, ODS save, unknown extension/kind);
  ready for adoption elsewhere.
- Per-key path persistence (`SaveLastUsed`/`LoadLastUsed` in
  `shell.cpp`): two-line file per key under the user-data dir.
- `UserDataDir()` extracted from the history path helper so the new
  per-key persistence shares the same XDG/AppData logic.
- New help-screen topic "Export"; user-facing `doc/user/analysis.md`
  gains an "Exporting" section; `DESIGN.md` gains a generics
  section covering the dialog / error modal / persistence / ODS
  writer; `DumpCommandsMd` now respects the `hidden` flag (the
  `connect` alias no longer appears in the auto-gen reference).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-16 12:03:39 +02:00

163 lines
7.2 KiB
Markdown

# essim — how the analysis classifies things
essim looks at signal names and the way pins are wired to decide
whether a net is a **power rail**, a **ground**, a **diff pair**, a
**bus**, etc. This page summarises those rules in plain language so you
know what to expect when you run `analyze` (the `[a]` shortcut on the
dashboard) or when you read the numbers on the home screen.
Nothing here mutates anything you cannot fix manually: every
inference can be overridden with `set-signal-type`, and the rules are
re-run on every `load` so the picture stays consistent with the
netlists currently in memory.
## Signal type — Power / Gnd / Other
Every signal is classified into one of three buckets.
**Gnd** if the name matches one of:
`GND`, `GROUND`, `EARTH`, `SHIELD`, `CHASSIS` (or starts with any of
those followed by `_`). The name alone is enough — false positives
here are essentially nil.
**Power** is a two-stage decision:
1. The name has to suggest power — it contains `PWR`, `POWER`,
`VCC`, `VDD`, `VEE`, `VSS`, `VBAT`, or starts with `VS_`, `VS3_`,
`+5V`-style or `-12V`-style prefixes.
2. The wiring has to corroborate it. essim requires at least one of:
- the signal lands on **4 or more pins** (a real rail goes to
decouplers + ICs + connectors, so it almost always has many
pads), or
- the name contains a **voltage value**`3V3`, `5V`, `12V`,
`0V9`, `5V0`, etc. (any `V` next to a digit).
*Hard floor*: a signal touching **fewer than 3 pins** is
**never** Power, even if both 1 and the voltage motif are
present. Physically you cannot have a rail on 1 or 2 pads.
**Other** in every other case.
This rule deliberately rejects things that look like power but
aren't: `PWR_OK` (status), `VSEL_0` (voltage select), `VDD_SENSE`
(sense feedback) — they all match step 1 but fail steps 2/3. The
analyze screen lists them under **Suspect Power** with the reason
attached (`fan-out 1, no voltage` etc.). Inspect, then either accept
the suspect status or force it back with `set-signal-type`.
## NC (no-connect) pins
A pin is shown as `(NC)` in the explore detail when it has no signal
attached. essim distinguishes three reasons:
- **Imported NC** — the netlist explicitly says the pin is
unconnected (Mentor format: signal name `unconnected` or
`unconnected (by TERM)`; Altium format: the pin is simply omitted
from every signal block).
- **Dropped singleton** — after import, essim removes every signal
that touches exactly one pin. A net with a single endpoint cannot
carry signal anywhere, so the pin is detached and tagged. This
catches both intentional sentinels and the per-IC `NC_*` labels
that customers often put on dead pads.
- **Filled at connect** — when you `connect` two parts that don't
agree on which pins exist (a Mentor part may have all pads, an
Altium part only the wired ones), essim materialises the missing
pads on the smaller side. They are unconnected *locally* on that
module but are bridged to a real signal on the other module via
the connection — so they do not count as orphans.
The dashboard's "NC" row summarises orphan counts (imported and
dropped only; filled-at-connect pins are excluded). The analyze
screen's "Types" tab adds a trailing line with the totals.
## Signal groups
essim groups signals that share an obvious structural pattern. They
are detected per module — a multi-card bus on the system is the BFS
union of the per-module groups it touches.
**Diff pair** — two signals named `STEM_P` and `STEM_N`
(case-insensitive, `_` required before the polarity letter). Both
halves must be present. Lone `_P` halves are flagged as orphans;
lone `_N` halves are *not* flagged (the `_N` suffix is overloaded
with active-low semantics — `RESET_N`, `BOOTMODE_N` — and flagging
them would flood the report).
**Diff bus** — at least two diff pairs whose stems share a common
prefix and only differ by a trailing index: `MDI0_P`/`MDI0_N`,
`MDI1_P`/`MDI1_N`, … → `MDI[0..3]_P/N`. Both `STEMN` and `STEM_N`
forms work (`MDI0`, `PCIE_TX_0`).
**Bus** — at least two signals with a common stem and a trailing
integer index. Two notations: `DATA[0]`, `DATA[1]`, … (bracketed)
or `ADDR_0`, `ADDR_1`, … (underscore — *strict*: an underscore is
required between the stem and the digits, so a name like
`GETH_01_VDD12` is *not* a bus).
**Anomalies** are emitted alongside groups:
- *Diff pair orphan*: a `_P` with no matching `_N`.
- *Diff bus gap*: e.g. `MDI[0..3]` has `MDI0`, `MDI1`, `MDI3` (`MDI2`
missing).
- *Bus gap*: same idea on plain buses.
Internal Mentor net names that start with `$` (like `$N12345`) are
skipped from every group/bus detection.
## Issues reported by `analyze`
The Issues tab of the analyze screen aggregates everything that
deserves attention:
| Tag | What it means |
|---|---|
| `[pin-role]` | A connector pin is typed (via `set-connector-type`) as Power or Gnd but the actual signal landing on it disagrees. |
| `[net-mix]` | A net bridged across modules carries both Power and Gnd signals — almost always a topology mistake. |
| `[diff-pair-orphan]` | `STEM_P` with no `STEM_N` in the same module. |
| `[bus-gap]` | A bus is missing one or more index values inside its range. |
| `[diff-bus-gap]` | A diff bus is missing one or more lane indices. |
Zero issues = the module passes every structural check essim knows
how to run today.
## Overrides
Every classification is advisory. To force a different type:
- **Signal type**: from the `explore` screen, press Enter on a
signal entry → a popup lets you pick `power` / `gnd` / `other`.
The same popup also opens when you press Enter on a pin row in
the parts detail (changes the pin's signal type) or on a net
member row in the signal detail (works across modules). Or type
`set-signal-type <module> <signal> <type>` in the console (or
from the palette).
- **Connector type**: from `explore` with `type = parts`, press
Enter on a part to jump to the dedicated `set-connector-type`
screen with that part pre-selected and the cursor on the type
input. The `set-connector-type` command also keeps working from
the console / palette.
- **Connector type**: `set-connector-type <module> <part> <connector-kind>`
(also via the dashboard `[t]` shortcut). This drives the pin role
expectations, which feed the `pin-role` check.
Overrides survive `save`/`restore` but are recomputed at every
`load` (i.e. the inference re-runs).
## Exporting
Dump structured data to an external file:
- `export connections <file>` — every wire pair, one row, with the
signals and types on both sides plus a `suspect` flag (name says
Power but the structural check disagreed) and a `mixed` flag
(both sides typed but disagreeing).
- The dashboard's `[x]` shortcut, the `export` command without
arguments, or the palette entry `export`: opens an interactive
file-picker dialog. A small toggle at the top of the dialog lets
you pick the format — **CSV** (flat, one row per wire) or
**ODS** (one sheet per connection, opens directly in
LibreOffice / Excel). The dialog remembers the directory and
filename you used last so the next export resumes from there.
- Inline scriptable form: `export connections /path/foo.csv` (or
`.ods`). Unknown extensions raise an error popup.