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Reverse Engineering Progress

Status: Complete (~99%)

What's Done

  1. Binary identification: toolkit/toolkit.exe is a PE32 Delphi/C++ Builder (RAD Studio) native x86 app, NOT .NET. ~10.4 MB, version 8.44.

  2. Help PDF fully read: All 47 pages of toolkit/Saturn PCB Toolkit Help.pdf analyzed. Contains UI screenshots, input/output descriptions, formula references, and example values (usable as test vectors).

  3. String extraction complete: All UI strings, material names, protocol presets, error messages, format strings, and formula references extracted from binary.

  4. 20+ note files written in docs/notes/:

    • 00-overview.md through 15-materials-data.md (16 calculator docs)
    • 16-rust-design-research.md — Rust implementation design decisions
    • ghidra-impedance.md — decompiled microstrip impedance calculator (610 lines)
    • ghidra-stripline.md — stripline solver analysis (790 lines)
    • ghidra-edge-coupled.md — 4 edge-coupled solver modes (754 lines)
    • ghidra-conductor-spacing.md — IPC-2221C spacing lookup analysis
    • ghidra-conductor-current.md — IPC-2152/2221A conductor current analysis (complete)
    • ghidra-fusing-inductor.md — Fusing current (Onderdonk) + Planar inductor (Mohan/Wheeler)
    • ghidra-ppm-reactance-mode15.md — PPM, Reactance, and Thermal Management solvers
    • ghidra-ohmslaw.md — Ohm's Law with 5 sub-modes including attenuators

  5. Material database extracted (46 materials + Air + Custom):

    • Complete ordered list from DFM ComboBox Items.Strings
    • 23 Er values extracted as strings from binary (see 15-materials-data.md)
    • Complete roughness factor mapping for all 45 materials (0.98 vs 1.0)
    • 9 Tg values extracted: 130, 170, 180, 260, 280, 240, 140, 165, 210
    • Materials 24-44 reuse same 23 Er string constants (exact mapping still needs full disassembly)

  6. Mode-to-handler mapping CORRECTED and VERIFIED:

    • Traced 15+ menu click handlers to their DAT_008d5f88 mode assignments
    • Previous mode names were incorrect for modes 2-18 (based on wrong assumptions)
    • All 19 solver modes now correctly identified (see NOTES.md)

  7. 40 functions renamed in Ghidra (project: saturn-pcb):

    • 19 solver functions with correct calculator names
    • 6 UI handler / pre-computation functions
    • 7 Delphi RTL helpers
    • 7 VCL control / math helpers
    • 5 menu click handlers

  8. IPC-2221C spacing table FULLY EXTRACTED:

    • Complete 8×9 lookup table (8 device types × 9 voltage ranges)
    • All 20 unique spacing values confirmed via disassembly

    • 500V linear formula for all 8 device types with slope/intercept constants

    • Documented in docs/notes/14-conductor-spacing.md

  9. All 19 solver functions decompiled/analyzed:

    • Mode 0: Microstrip (Hammerstad-Jensen) — full decompilation
    • Mode 1: Stripline (Cohn/Wadell) — disassembly analysis, constants confirmed
    • Mode 2: Conductor Current (IPC-2152/2221A) — full disassembly analysis, all formulas + modifier tables
    • Mode 3: Edge Coupled External — decompiled
    • Mode 4: Differential Pairs (Edge Coupled Int Sym) — disassembly analysis
    • Mode 5: Embedded Microstrip (Edge Coupled Int Asym) — decompiled
    • Mode 6: Er Effective (Edge Coupled Embedded) — decompiled
    • Mode 7: Fusing Current (Onderdonk) — decompiled, constants confirmed (Tm=1084.62°C)
    • Mode 8: Wire Gauge Properties — decompiled, AWG lookup table (NOT broadside coupled impedance)
    • Mode 9: Conductor Spacing — complete table extraction
    • Mode 10: Ohm's Law — full disassembly (E-I-R, LED bias, voltage divider, R/C/L, Pi/T-pad attenuators)
    • Mode 11: Padstack — decompiled, all 7 sub-types with geometry formulas
    • Mode 12: PDN Impedance — full decompilation, 3 formulas verified against Help PDF
    • Mode 13: Planar Inductor (Mohan/Wheeler) — decompiled, Saturn-specific K1/K2 for circular shape
    • Mode 14: PPM Calculator — decompiled, Hz↔PPM + XTAL load cap formulas
    • Mode 15: Thermal Management — identified, basic analysis done
    • Mode 16: Via Properties — full disassembly, 16 formulas, Goldfarb capacitance, Simonovich diff via
    • Mode 17: Wavelength — full decompilation
    • Mode 18: Reactance — decompiled, standard Xc/Xl/f_res formulas

  10. Physical constants verified at specific binary addresses:

    • Speed of light, µ₀, ε₀, copper resistivity/temp coeff
    • All unit conversion factors (mil/mm/inch)
    • PCB thickness table (0.254mm to 2.286mm in 9 steps)

  11. PE section mapping resolved:

    • .text: VA 0x00401000 - 0x00871000, file 0x600
    • .data: VA 0x00871000 - 0x00905000, file 0x46fc00
    • Correct VA-to-file-offset conversion documented

What's NOT Done

  1. Crosstalk calculator: Uses a separate form, doesn't go through the main dispatcher. Handler at 0x004bde04 is in an unanalyzed region of the binary. Low priority (marked "unsupported" in original).

  2. PDN Impedance (Mode 12): DONE. Three formulas verified with test vectors from Help PDF.

  3. Stripline formula cleanup: DONE. 941-line cross-reference document with clean Rust pseudocode. See stripline-formulas-clean.md.

Resolved Items

  • All 19 solver modes analyzed — Mode 8 = wire gauge property lookup, Mode 16 = Via Properties (16 formulas).
  • Er-to-material mapping COMPLETE: All 46 materials fully mapped from ComboBox1Change disassembly. Major correction: 21 of 23 materials had wrong Er in earlier notes due to sequential string assumption. See materials-er-mapping.md.
  • Thermal Management (Mode 15) COMPLETE: Simple formula T_j = R_theta * P + T_ambient. The "opaque PreCompute_3" was just ambient temperature read. See ghidra-thermal-management.md.
  • Impedance sub-mode routing: Each mode has its own menu click handler, not RadioGroup-switched.
  • Via capacitance: Uses Goldfarb constant 1.41, NOT 4/π. The 4/π constant at 0x004BA940 is only used in Solver_FusingCurrent.
  • Math function corrections: FUN_008673c0 = log10 (not sqrt), FUN_008675ac = pow (not ln). Correct: FUN_00867350 = ln, FUN_00868834 = sqrt.
  • RO4350 Er bug found: Impedance form uses Er=3.66 (correct), crosstalk form uses Er=3.48 (bug).
  • Stripline Cohn/Wadell formula cleanup COMPLETE: Saturn uses hybrid approach with proprietary empirical corrections. 60+ constants mapped, Wadell/Cohn/IPC-2141A formulas cross-referenced, clean Rust pseudocode ready. See stripline-formulas-clean.md.

Ghidra Project State

Project: saturn-pcb (at ~/.cache/ghidra-cli/projects/)
Program: toolkit.exe
Analysis: Complete (14,689 functions)
Named functions: 40+

How to Resume

# 1. Kill any lingering ghidra processes
pkill -9 -f GhidraCliBridge
pkill -9 -f "ghidra.GhidraClassLoader"
sleep 3

# 2. Clean up lock and bridge files
rm -f ~/.cache/ghidra-cli/projects/saturn-pcb.lock~
rm -f ~/.local/share/ghidra-cli/bridge-*.port
rm -f ~/.local/share/ghidra-cli/bridge-*.pid

# 3. If project was deleted, reimport WITHOUT analysis first:
~/.local/share/ghidra-cli/ghidra/ghidra_12.0.1_PUBLIC/support/analyzeHeadless \
  ~/.cache/ghidra-cli/projects saturn-pcb \
  -import toolkit/toolkit.exe -overwrite -noanalysis

# 4. Then analyze separately with memory limits:
~/.local/share/ghidra-cli/ghidra/ghidra_12.0.1_PUBLIC/support/analyzeHeadless \
  ~/.cache/ghidra-cli/projects saturn-pcb \
  -process toolkit.exe -analysisTimeoutPerFile 900 -max-cpu 1

# 5. Set defaults:
ghidra set-default project saturn-pcb
ghidra set-default program toolkit.exe

Priority for Next Session

  1. Begin Rust implementation using extracted formulas and table data
  2. All reverse engineering is complete — all 19 modes have clean, implementable formulas

Files Summary

  • NOTES.md — Master consolidated notes (all findings, handler mapping)
  • PROGRESS.md — This file
  • docs/notes/00-overview.md through 15-materials-data.md — Per-calculator notes
  • docs/notes/16-rust-design-research.md — Rust design decisions
  • docs/notes/ghidra-impedance.md — Decompiled microstrip impedance (610 lines)
  • docs/notes/ghidra-stripline.md — Stripline solver analysis (790 lines)
  • docs/notes/ghidra-edge-coupled.md — Edge-coupled solver analysis (754 lines)
  • docs/notes/ghidra-conductor-spacing.md — IPC-2221C spacing analysis
  • docs/notes/ghidra-conductor-current.md — IPC-2152/2221A conductor current (complete)
  • docs/notes/ghidra-fusing-inductor.md — Fusing current + Planar inductor decompilation
  • docs/notes/ghidra-ppm-reactance-mode15.md — PPM, Reactance, Thermal Management
  • docs/notes/ghidra-ohmslaw.md — Ohm's Law with 5 sub-modes + attenuators
  • docs/notes/ghidra-padstack.md — Padstack calculator (7 sub-types)
  • docs/notes/ghidra-broadside-coupled.md — Mode 8 wire gauge lookup (44 AWG entries)
  • docs/notes/ghidra-via-properties.md — Via Properties (16 formulas, 53KB function)
  • docs/notes/ghidra-thermal-management.md — Thermal Management (T_j = R*P + T_ambient)
  • docs/notes/materials-er-mapping.md — Complete Er/Tg mapping for all 46 materials
  • docs/notes/ghidra-pdn-impedance.md — PDN Impedance (3 formulas, test vectors)
  • docs/notes/stripline-formulas-clean.md — Stripline cross-reference: Cohn/Wadell/IPC-2141A vs Saturn (941 lines)