GxEPD2-esphome/esphome-zepd/components/zepd/engine_model.h

#pragma once

#include <cstdint>

namespace esphome::zepd {

// One command byte plus its (fixed, compile-time) data bytes, as sent by
// GxEPD2_EPD::_writeCommand()/_writeData(). delay_before_ms/delay_after_ms
// and wait_busy_after mirror the fixed delay()s and _waitWhileBusy() calls
// bracketing specific commands in the vendor source (which command gets
// which varies per panel - e.g. GxEPD2_213_Z98c delays 10ms on both sides
// of its SWRESET, while GxEPD2_154_Z90c busy-waits after its SWRESET
// instead). At most one of delay_after_ms/wait_busy_after is expected to be
// set on any one command.
struct EpdCommand {
  uint8_t cmd;
  const uint8_t *data;  // nullptr if the command takes no data bytes
  uint8_t data_len;
  uint16_t delay_before_ms{0};
  uint16_t delay_after_ms{0};
  bool wait_busy_after{false};
};

// One palette entry for a packed (bits_per_pixel > 1) panel: a reference
// RGB color (ESPHome Color space, 0-255 per channel) and the wire code the
// controller uses for it. Classification at draw time picks the entry
// nearest the drawn color, with exact matches winning - so named colors map
// deterministically, the way GxEPD2's own color4()/color7() switch does.
// Several entries may share a code (GxEPD2 maps green and orange both onto
// the 4-color yellow code, and blue onto black).
struct EpdPaletteEntry {
  uint8_t r, g, b;
  uint8_t code;
};

// Standard GxEPD2 4-color (BWRY) palette - codes per GxEPD2_4C.h color4():
// black=0x00, white=0x01, yellow/green/orange=0x02, red=0x03, blue->black.
inline const EpdPaletteEntry PALETTE_4C[] = {
    {0x00, 0x00, 0x00, 0x00},  // black
    {0xFF, 0xFF, 0xFF, 0x01},  // white
    {0xFF, 0xFF, 0x00, 0x02},  // yellow
    {0x00, 0xFF, 0x00, 0x02},  // green  -> yellow code
    {0xFF, 0xA4, 0x00, 0x02},  // orange -> yellow code
    {0xFF, 0x00, 0x00, 0x03},  // red
    {0x00, 0x00, 0xFF, 0x00},  // blue   -> black code
};
inline const uint8_t PALETTE_4C_LEN = sizeof(PALETTE_4C) / sizeof(PALETTE_4C[0]);

// Standard ACeP 7-color palette - codes per GxEPD2_7C.h color7(): black=0x00,
// white=0x01, green=0x02, blue=0x03, red=0x04, yellow=0x05, orange=0x06.
inline const EpdPaletteEntry PALETTE_7C[] = {
    {0x00, 0x00, 0x00, 0x00},  // black
    {0xFF, 0xFF, 0xFF, 0x01},  // white
    {0x00, 0xFF, 0x00, 0x02},  // green
    {0x00, 0x00, 0xFF, 0x03},  // blue
    {0xFF, 0x00, 0x00, 0x04},  // red
    {0xFF, 0xFF, 0x00, 0x05},  // yellow
    {0xFF, 0xA4, 0x00, 0x06},  // orange
};
inline const uint8_t PALETTE_7C_LEN = sizeof(PALETTE_7C) / sizeof(PALETTE_7C[0]);

// Everything the engine needs to drive one panel - this is the codegen'd
// "engine model" produced from a model's drivers/<model>.json (see
// ../../../../claude/DESCRIPTOR_REGISTRY_PLAN.md), hand-derived today from a
// GxEPD2 vendor driver's .cpp/.h the same way the legacy
// components/gxepd2/panel_*.h files were. Only what the engine actually
// uses - the RAM-window-set command layout (0x44/0x45/0x4E/0x4F) is common
// to every panel inspected so far and is hardcoded in Engine itself rather
// than made part of this struct; revisit if/when a controller family turns
// up that lays it out differently.
//
// Order in which the engine emits a plane's wire lines, derived by the diag
// native-path tool. The buffer always holds `height` rows of real pixels;
// this controls only which buffer row each wire line carries and how many
// wire lines there are, so wire length can exceed buffer size.
//   SEQUENTIAL   - wire line i carries buffer row i; line count == height.
//                  Every single-region panel captured so far.
//   PAIRED_EDGES - the controller fills a 2x-height RAM scanned from both
//                  edges toward the middle: for i in [0,height) it wants
//                  buffer row (height-1-i) then row i, so line count ==
//                  2*height and each row is sent twice. GDEY0579F51 / HX8717.
//                  This is exactly what GxEPD2's writeNative emits for that
//                  panel (99 bytes/line x 544 lines/region), so a faithful
//                  replay needs it - nothing panel-specific in the engine.
enum class LineOrder : uint8_t { SEQUENTIAL, PAIRED_EDGES };

struct EngineModel {
  uint16_t width;
  uint16_t height;
  bool busy_active_level;    // digitalRead() level meaning "still busy"
  uint32_t busy_timeout_ms;  // ceiling for every busy wait (init and refresh alike)

  const EpdCommand *init_sequence;  // run once, after the reset pulse
  uint8_t init_sequence_len;

  // Sets the (always full-frame, since this engine has no partial-window
  // support) RAM addressing window. window_sequence[0] runs once after
  // init_sequence and before the first plane's byte burst; index 1 is only
  // used when window_per_plane is true (see below). Was hardcoded assuming
  // every controller shares SSD1680's 0x44/0x45/0x4E/0x4F byte-column
  // layout - GxEPD2_426_GDEQ0426T82 (SSD1677) turned out to address in raw
  // pixels with reversed Y and re-issues its entry-mode command here, and
  // GxEPD2_583_GDEQ0583T31 (UC8179) uses one 0x90 command bracketed by
  // 0x91/0x92 markers instead. Made per-model data, same as init/refresh,
  // rather than special-cased in the engine.
  const EpdCommand *window_sequence[2];
  uint8_t window_sequence_len[2];

  // true if each plane needs window_sequence[plane index] re-run before
  // its own byte burst, instead of one window_sequence[0] covering every
  // plane's burst (the default, e.g. a BW+red panel's shared full-frame
  // window). This is how a panel with real master/slave regions (two
  // genuinely separate physical RAM windows, not just two color planes
  // sharing one) is handled - "plane" here just means "one more buffer
  // with its own byte burst," which happens to fit a two-physical-region
  // panel as well as a two-color-plane one.
  bool window_per_plane{false};

  uint8_t plane_count;          // 1 (BW), 2 (BW + accent color), or 2 physical regions
  uint8_t plane_write_cmd[2];   // e.g. {0x24, 0x26}

  // The extra "previous RAM bank" write GxEPD2's writeImageForFullRefresh()
  // makes that plain writeImage() doesn't, on controllers where the two
  // diverge (SSD1680/SSD1681/SSD1619-family: 0x26 then 0x24, or 0x10 then
  // 0x13 - same bitmap written twice, to two different commands). 0x00 (the
  // default) means no divergence was observed: writeImageForFullRefresh
  // falls back to writeImage for that controller, the common case. NOT read
  // by Engine today - this engine always does a plain single write per
  // plane, correct for full-refresh-only operation, since the full-refresh
  // waveform doesn't depend on the "previous" bank's content. It matters
  // once partial refresh reads that bank to compute its diff, so it's
  // captured now rather than needing a second capture pass later.
  uint8_t plane_write_cmd_for_full_refresh[2]{0, 0};

  bool plane_invert[2];         // true if the byte must be bit-inverted on write

  // When window_per_plane is true, each plane's own buffer is sized for
  // this width, not the descriptor's overall `width` (which is the full
  // logical canvas the adapter draws into) - e.g. 396 for GDEY0579F51's
  // master/slave halves, each 396x272 on its own, not the full 792x272.
  // Unused otherwise.
  uint16_t plane_width{0};

  // Wire-line emission order for this panel's plane(s) - see LineOrder
  // above. Default SEQUENTIAL; PAIRED_EDGES is not assumed for any panel
  // without the diag native-path tool deriving it.
  LineOrder line_order{LineOrder::SEQUENTIAL};

  // Pixel bit-depth, which also selects the buffer model:
  //   1 = one-bit-per-pixel plane model (mono, or BW + accent as two
  //       separate 1bpp planes). plane_invert applies; palette is unused.
  //   2 = packed 4-color: 2 bits/pixel, 4 pixels/byte, MSB-first.
  //   4 = packed 7-color (ACeP): 4 bits/pixel, 2 pixels/byte, MSB-first.
  // For bits_per_pixel > 1 the buffer is a single packed code-per-pixel
  // stream (per region when window_per_plane), sized width*height*bpp/8,
  // and each pixel's wire code comes from `palette` (nearest-color
  // classification at draw time) rather than the 1bpp plane bitmasks;
  // plane_invert is unused.
  uint8_t bits_per_pixel{1};

  // Packed-mode (bits_per_pixel > 1) palette and the wire code the buffer is
  // cleared to (the panel's white/blank). Unused when bits_per_pixel == 1.
  // See PALETTE_4C / PALETTE_7C.
  const EpdPaletteEntry *palette{nullptr};
  uint8_t palette_len{0};
  uint8_t blank_code{0};

  const EpdCommand *refresh_sequence;  // e.g. 0x22/0xF7 then trigger 0x20
  uint8_t refresh_sequence_len;

  // powerOff()/hibernate(), captured the same way as refresh_sequence.
  // Exposed for a user's own lambda (Engine::request_power_off/
  // request_hibernate), not run automatically by update(): this engine does
  // a full hardware reset on every cycle regardless of prior power state,
  // so correctness never depends on calling either. hibernate_sequence is
  // the deep-sleep trigger ONLY (every GxEPD2 driver's hibernate() is
  // powerOff() + one more command when rst is wired) - Engine runs
  // power_off_sequence first, then hibernate_sequence, to replay the same
  // two-step effect. Both nullptr/0 (not yet captured) is a safe no-op:
  // Engine treats a zero-length sequence as already done.
  const EpdCommand *power_off_sequence{nullptr};
  uint8_t power_off_sequence_len{0};
  const EpdCommand *hibernate_sequence{nullptr};  // deep-sleep trigger only, after power_off_sequence
  uint8_t hibernate_sequence_len{0};
};

}  // namespace esphome::zepd