mesen_chrRamWriteCounter.lua

--Script for writing to CHR-RAM count per frame
--Emulator: Mesen 0.9.4
--Rom: any with CHR-RAM
--Author: spiiin

writeToChr0 = 0;
writeToChr1 = 0;

writedBetweenFrames0 = 0;
writedBetweenFrames1 = 0;

colorCode = 0x4000FF00;

function onStartFrame()
    --old frame ended, and new started.
    --we can measure byte counts writen only between frames
    writedBetweenFrames0 = writeToChr0;
    writedBetweenFrames1 = writeToChr1;
end

function onEndFrame()
    emu.log("Frame ended, chr0 writes: "..writeToChr0.." (between frames:"..writedBetweenFrames0..")"..", chr1 writes: "..writeToChr1.." (between frames:"..writedBetweenFrames1..")");
    writeToChr0 = 0;
    writeToChr1 = 0;
end

function highlightScanline()
    local state = emu.getState();
    local color = colorCode + state.ppu.scanline;
    --emu.log("scanline: "..tostring(state.ppu.scanline));
    emu.drawLine(0, state.ppu.scanline, 256, state.ppu.scanline, color, 1);
end

function onChrWrite(address, value)
    if (address < 0x1000) then
      writeToChr0 = writeToChr0 + 1;
    else
      writeToChr1 = writeToChr1 + 1;
    end;
    --emu.log("address: "..address.." value: "..value.." chr0writes: ".. writeToChr0);
end

emu.addEventCallback(onStartFrame, emu.eventType.startFrame);
emu.addEventCallback(onEndFrame, emu.eventType.endFrame);
emu.addMemoryCallback(onChrWrite, emu.memCallbackType.ppuWrite, 0x0000, 0x1FFF);
emu.addMemoryCallback(highlightScanline, emu.memCallbackType.ppuWrite, 0x0000, 0x3FFF);

emu.displayMessage("Script", "Script loaded.")