-- demo\rosetta\Compiler\cgen.exw
--  Generates 32-bit machine code (see note in vm.exw)
without js -- (machine code!)
include cgen.e

function get_var_name(atom addr)
    integer n = (addr-var_mem)/4+1
    if n<1 or n>length(vars) then ?9/0 end if
    return vars[n]
end function

function hxl(integer pc, object oh, string fmt, sequence args={})
-- helper routine to display the octal/hex bytes just decoded,
-- along with the code offset and the human-readable text.
    if length(args) then fmt = sprintf(fmt,args) end if
    sequence octhex = {}
    atom base = code_mem+pc
    integer len = 0
    if integer(oh) then -- all octal
        for i=1 to oh do
            octhex = append(octhex,sprintf("0o%03o",peek(base)))
            base += 1
        end for
        len = oh
    else    -- some octal and some hex
        for i=1 to length(oh) by 2 do
            for j=1 to oh[i] do
                octhex = append(octhex,sprintf("0o%03o",peek(base)))
                base += 1
            end for
            len += oh[i]
            for j=1 to oh[i+1] do
                octhex = append(octhex,sprintf("#%02x",peek(base)))
                base += 1
            end for
            len += oh[i+1]
        end for
    end if
    printf(output_file,"%4d: %-30s %s\n",{pc+1,join(octhex,","),fmt})
    return len
end function

constant cccodes = {"o?" ,"no?","b?" ,"ae?","z" ,"ne" ,"be?","a?",
--                    0  ,  1  ,  2  ,  3  ,  4 ,  5  ,  6  , 7  ,
                    "s?" ,"ns?","pe?","po?","l" ,"ge" ,"le" ,"g" }
--                    8  ,  9  , 10  , 11  , 12 , 13  , 14  , 15

constant regs = {"eax","ecx","edx"} -- (others as/when needed)

procedure decode()
-- for a much more complete (and better organised) disassembler, see p2asm.e
integer pc = 0, -- nb 0-based
        opcode, xrm

    while pc<length(code) do
        opcode = peek(code_mem+pc)
        xrm = -1
        switch opcode do
            case 0o150:
                atom vaddr = peek4s(code_mem+pc+1)
                integer n = find(vaddr,stringptrs)
                object arg = iff(n?enquote(strings[n])
                                  :sprintf("%d",vaddr))
                pc += hxl(pc,{1,4},"push %s",{arg})
            case 0o217:
            case 0o377:
                integer n = find(opcode,{0o217,0o377})
                string op = {"pop","push"}[n]
                xrm = peek(code_mem+pc+1)
                if n!=find(xrm,{0o005,0o065}) then exit end if
                atom addr = peek4u(code_mem+pc+2)
                pc += hxl(pc,{2,4},"%s [%s]",{op,get_var_name(addr)})
            case 0o061:
            case 0o071:
            case 0o205:
                integer n = find(opcode,{0o061,0o071,0o205})
                string op = {"xor","cmp","test"}[n]
                xrm = peek(code_mem+pc+1)
                if and_bits(xrm,0o300)!=0o300 then exit end if
                string r1 = regs[and_bits(xrm,0o070)/0o010+1]
                string r2 = regs[and_bits(xrm,0o007)+1]
                pc += hxl(pc,2,"%s %s,%s",{op,r1,r2})
            case 0o017:
                xrm = peek(code_mem+pc+1)
                switch xrm do
                    case 0o224:
                    case 0o225:
                    case 0o234:
                    case 0o235:
                    case 0o236:
                    case 0o237:
                        string cc = cccodes[and_bits(xrm,0o017)+1]
                        xrm = peek(code_mem+pc+2)
                        if xrm=0o300 then
                            pc += hxl(pc,3,"set%s al",{cc})
                        elsif xrm=0o301 then
                            pc += hxl(pc,3,"set%s cl",{cc})
                        else
                            exit
                        end if
                    case 0o204:
                        integer offset = peek4s(code_mem+pc+2)
                        pc += hxl(pc,{2,4},"jz %d",{pc+6+offset+1})
                    else
                        exit
                end switch
            case 0o010:
            case 0o040:
                xrm = peek(code_mem+pc+1)
                if xrm=0o310 then
                    string lop = {"or","and"}[find(opcode,{0o010,0o040})]
                    pc += hxl(pc,2,"%s al,cl",{lop})
                else
                    exit
                end if
            case 0o120:
            case 0o122:
            case 0o130:
            case 0o131:
            case 0o132:
                string op = {"push","pop"}[find(and_bits(opcode,0o070),{0o020,0o030})]
                string reg = regs[and_bits(opcode,0o007)+1]
                pc += hxl(pc,1,"%s %s",{op,reg})
            case 0o231:
                pc += hxl(pc,1,"cdq")
            case 0o164:
            case 0o353:
                string jop = iff(opcode=0o164?"jz":"jmp")
                integer offset = peek1s(code_mem+pc+1)
                pc += hxl(pc,{1,1},"%s %d",{jop,pc+2+offset+1})
            case 0o351:
                integer offset = peek4s(code_mem+pc+1)
                pc += hxl(pc,{1,4},"jmp %d",{pc+5+offset+1})
            case 0o303:
                pc += hxl(pc,1,"ret")
            case 0o350:
                integer offset = peek4s(code_mem+pc+1)
                atom addr = offset+code_mem+pc+5
                integer n = find(addr,builtins)
                pc += hxl(pc,{1,4},"call :%s",{builtin_names[n]})
            case 0o001:
            case 0o041:
            case 0o051:
                integer n = find(opcode,{0o001,0o041,0o051})
                string op = {"add","and","sub"}[n]
                xrm = peek(code_mem+pc+1)
                switch xrm do
                    case 0o004:
                        if peek(code_mem+pc+2)=0o044 then
                            pc += hxl(pc,3,"%s [esp],eax",{op})
                        else
                            exit
                        end if
                    else
                        exit
                end switch
            case 0o367:
                xrm = peek(code_mem+pc+1)
                if and_bits(xrm,0o300)!=0o300 then exit end if
                integer n = find(and_bits(xrm,0o070),{0o030,0o040,0o070})
                if n=0 then exit end if
                string op = {"neg","mul","idiv"}[n]
                string reg = regs[and_bits(xrm,0o007)+1]
                pc += hxl(pc,2,"%s %s",{op,reg})
            else
                exit
        end switch
    end while
    if pc<length(code) then
        ?"incomplete:"
        if xrm=-1 then
            ?{pc+1,sprintf("0o%03o",opcode)}
        else
            ?{pc+1,sprintf("0o%03o 0o%03o",{opcode,xrm})}
        end if
    end if
end procedure

procedure main(sequence cl)
    open_files(cl)
    toks = lex()
    object t = parse()
    code_gen(t)
    fixup()
    decode()
    free({var_mem,code_mem})
    close_files()
end procedure

--main(command_line())
main({0,0,"gcd.c"})