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Checksum Scripts

Lua scripts can serve as custom checksum calculators. Assigned via Settings > Checksum Settings — the dialog shows a single combo box with built-in algorithms and scripts.

The @checksum-script marker​

Add -- @checksum-script in the first 512 bytes of the script. Only scripts with this marker appear in the Checksum Settings dialog.

Behavior​

  • When a target with a script mapping is selected, the script runs automatically.
  • The script calls mp.ui.set_statusbar(label, value) — standard checksum widgets are hidden, the status bar shows a single "label: value" string.
  • When switching to a target without a script mapping, mp.ui.reset_statusbar() restores standard widgets automatically.

Mappings​

Stored in <config>/checksum_profiles.json:

[
  {
    "target_pattern": "K0R Auto Target",
    "checksum_name": "",
    "script_name": "renesas_nec_checksum.lua"
  }
]

Example: renesas_nec_checksum.lua​

-- renesas_nec_checksum.lua
-- @checksum-script
-- Calculates SUM-RL78 for Renesas RL78 (0x000-0x3FF)
-- and NEC 78K0R/78K0 (0x000-0x7FF)

local cfg = mp.config.get()
local target = cfg.target or ""
local family = cfg.family or ""

local RANGES = {
    { pattern = "RL78",  start_addr = 0x0000, length = 0x400 },  -- 1 KB
    { pattern = "78K0R", start_addr = 0x0000, length = 0x800 },  -- 2 KB
    { pattern = "78K0",  start_addr = 0x0000, length = 0x800 },  -- 2 KB
}

local range = nil
for _, r in ipairs(RANGES) do
    if family:find(r.pattern) or target:find(r.pattern) then
        range = r; break
    end
end
if not range then
    mp.log.warn("renesas_nec_checksum: unknown family, using default 0x400")
    range = { start_addr = 0x0000, length = 0x400 }
end

local region = mp.memory.get_regions()[1]
local data = mp.memory.read_range(region, range.start_addr, range.length)
local sum = mp.checksum.sum_rl78(data)

mp.ui.set_statusbar(target .. " Block 0", string.format("0x%04X", sum))

This script ships in scripts/examples/renesas_nec_checksum.lua and is wired in by default for RL78 / 78K0R / 78K0 targets.