MegaProcessor

function ProcessFile( inFileName )
    local inFile = Check( io.open(inFileName,"r"),
                        "Can't open file " .. inFileName
                        );

    for l in inFile:lines() do
        io.write( string.format("%04d  ", LineNr) );        
        ProcessLine( Chomp(l) );
        LineNr = LineNr + 1;
    end
end

function Fields( line )
    if( line == "" or line:match("^%s*[;//]") ) then return 0; end;

    if( asm_instr ) then
        insLen = asm_instr[1];
        if( type(insLen)== 'function' ) then insLen = insLen(f2,f3,f4) end;
        b1, b2, b3 = asm_instr[2](f2,f3,f4);
    end
    n, formBytes = fmtBytes(b1, b2, b3);

    io.write( string.format("%d:%s",insLen,formBytes) ); print( l );

end


-- Main line
--
if( not arg[1] ) then

#!/usr/bin/env lua

function printf( f, ... )
    io.write( string.format(f, ...) );
end

function htob_2( s )
    local hi,lo = s:byte(1,2);
    local hiA,loA;

    hi = bit32.band(hi,0xDF);   hiA = bit32.band(hi,0x0F);
    lo = bit32.band(lo,0xDF);   loA = bit32.band(lo,0x0F);

    if( hi >= 0x40 ) then hiA = hiA + 9 end
    if( lo >= 0x40 ) then loA = loA + 9 end

    return( bit32.bor( bit32.lshift(hiA,4), loA ) );
end

--
-- Disassembly function for instructions 0xd8..0xdf
-- which take one post-byte
-- The lower-case 'd' in each line will be replaced with the destination (0..3)
-- as derived from the instruction.
--

"ROXL   Rd, R",    -- 0xe0..0xe3  :   0xe4..0xe7  :   "-- redundant"
"ROXL.WT Rd, R",   -- 0xe8..0xeb  :    0xec..0xef  :   "-- redundant"
"ROXR   Rd, R",   -- 0xf0..0xf3  : 0xf4..0xf7  :   "-- redundant"
"ROXR.WT Rd, R"    -- 0xf8..0xfb  :    0xfc..0xff  :   "-- redundant"
};

function dis_d8_db( instr, postb)
        printf( "%02x %02x .. : ", instr, postb );
        
        if( instr >= 0xd8 and instr <= 0xdb ) then
            local dst = bit32.band( instr, 0x03 );
            local src = bit32.rshift(postb,3);
            local result = I_d8_db[src]:gsub("d",tostring(dst),1);
            local lastChar = result:sub(-1);
            if( lastChar == 'R' ) then result = result .. tostring( bit32.band( postb,0x03) ) end;

"BCLR  Rd, #",
"BCLR  Rd, R",
"BSET  Rd, #",
"BSET  Rd, R"
};

function dis_dc_df( instr, postb)
        printf( "%02x %02x .. : ", instr, postb );
        if( instr >= 0xdc and instr <= 0xdf ) then
                local dst = bit32.band(instr, 0x03);
                local src = bit32.rshift(postb,5);
                -- printf( "%02x %02x", dst, src );
                local result = I_dc_df[src]:gsub("d",tostring(dst),1);
                local lastchar = result:sub(-1);
                if( lastchar == '#' ) then result = result .. tostring( bit32.band(postb,0x0f) ) end;

--
-- File: lib.lua
-- usage: require('lib');  
--    as early as possible, preferrably before all other requires,
--

















--
-- If cond evaluates to false (or nil), then print errmsg
-- otherwise, return the condition.
--
function Check( cond, errmsg )
    errmsg = errmsg or "Check failed..";
    if( not cond ) then

#!/usr/bin/env lua
--
-- Evaluation test for the Megaprocessor instructions 0xd8..0xdf
-- to show that the result of (instruction & 0x03) yields the correct number for
-- the destination register (R0..R3) in all 8 cases.
--
--

function printf( f, ... )
	print( string.format(f, ...) );
end

firstbyte = {}

for i=0,7 do
	firstbyte[i+1] = 0xd8+i;
	dest = bit32.band(firstbyte[i+1],0x03);
	printf( "%02x : R%1x", firstbyte[i+1], dest );
end