lsnes: current instruction on screen

-- this outputs the current line of trace logger on screen
-- very basic and not well tested, but helps when executing SNES' open bus, which is bugged on bsnes

local PFLAGS_ON = string.reverse("NVMXDIZC")
local PFLAGS_OFF = string.lower(PFLAGS_ON)

function on_paint(frame_advance)
    gui.top_gap(32)
    gui.left_gap(24)
    gui.right_gap(24)

    local previous_bus = memory.getregister("pbpc")
    local A, X, Y, S = memory.getregister("a"), memory.getregister("x"), memory.getregister("y"), memory.getregister("s")
    local D, DB = memory.getregister("d"), memory.getregister("db")
    local processor_flags = bit.rflagdecode(memory.getregister("p"), 8, PFLAGS_ON, PFLAGS_OFF)
    local V, H = memory.getregister("vcounter"), memory.getregister("hcounter")
    local code = memory.disassemble("snes-XA", 0x1000000 + previous_bus, 1)[1].disasm

    local log_text = string.format("%.6x  A:%.4x X:%.4x Y:%.4x S:%.4x D:%.4x DB:%.2x %s V:%3d H:%4d",
                                    previous_bus, A, X, Y, S, D, DB, processor_flags, V, H)
    gui.text(-24, -32, log_text, "white", "darkblue")
    gui.text(-24, -16, code, "red", "darkblue")
end

gui.repaint()